Theorem V: Consciousness is a Special Kind of Reentrant Signaling State
6.1 Definition of consciousness
If we inspect our minds while we are not doing anything in particular, we will find that there are many mental processes going on simultaneously as resting-state mental processes, such as thinking casually, experiencing light mood, perceiving trivial sensations (inactive vision, soft sound, light touch, etc. from the uneventful surroundings), being aware of space and time, being aware of self, and being aware of these on-going conscious mental processes. When there is a strong enough stimulus, either external (a flash of light, a loud call, a sharp pain, etc.) or internal (a popping-up thought of an urgent task, a sudden reliving of an exciting incident, a pang of sorrow, etc.), there is a mental process or mental processes that register this stimulus, direct our attention to, and keep our concentration on that stimulus, and our mind will become less aware of the resting-state mental processes that are not related to the stimulus. For example, when there is an exciting news on the television and we turn to watch it, we may not be aware of the sounds in the surroundings, not register the pain in our back, and not feel any emotion that we had before. In some circumstances, some of these mental processes may even cease functioning for a while, such as when we are overwhelmed by a strong emotion, we may be stunned and unable to think for a while, or when we are intensely concentrating on solving a difficult problem, we may not experience any mood for that period of time. But, whether we are doing nothing in particular or concentrating on something, there is one mental process that is always working when we are conscious. That mental process functions to be consciously aware of the functions of other mental processes (such as a visual perception, an auditory perception, a touch perception, an emotion, and a thought) and the function of itself, with the awareness of what their phenomenal characteristics are like (e.g., with the awareness of what the colors are like, of what the sounds are like, what the touch feelings are like, what the emotions are like, and what the thoughts are like) occurring. But, as discussed in section 3.2, when we are consciously aware of something, we also consciously experience that thing too. Therefore, when we are conscious, there is always one mental process occurring that functions to be consciously aware of and consciously experience mental process functions (including that of itself). In this theory, this mental process will be called consciousness mental process, and it can be defined as:
Definition. Consciousness mental process is the mental process that functions to be consciously aware of and consciously experience mental process functions.
It is to be note that the consciousness mental process does not functions to be consciously aware of and consciously experience all mental process functions. Some mental processes are not accessible to the consciousness mental process, and it can neither be aware of nor experience their functions . These mental processes are called sub-conscious or unconscious mental processes. Mental processes whose functions the consciousness mental process can be aware of and experience are called conscious mental processes (which are different from the consciousness mental process). And it is only the functions of these mental processes that the consciousness mental process functions to be aware of and experience. Because, when the consciousness mental process functions to be aware of and experience these conscious mental processes’ functions, the awareness of what their phenomenal characteristics are like occurs, these conscious mental processes’ functions must have consciously experienceable phenomenal characteristics. This means that all conscious mental processes’ functions are qualia and that the consciousness mental process is aware of and experiences only these mental processes’ functions, which are qualia.
To reiterate, when the consciousness mental process functions to be aware of and experience qualia, awareness and experiences of qualia, with the awareness of what the qualia’s phenomenal characteristics are like occurring, occur. From the definitions of conscious awareness and conscious experiences in section 3.2, it can thus be concluded that the consciousness mental process is the mental process that functions to create conscious awareness and experiences. (N.B. From now on, whenever conciseness is required, the term “conscious awareness and conscious experiences” will be abbreviated to “conscious awareness and experiences”.) But, in a normal condition, the consciousness mental process creates conscious awareness and experiences of several mental process functions (such as those of a visual perception, an auditory perception, a touch perception, an emotion, and a thought) simultaneously. So, in a normal condition, the consciousness mental process creates the composite of all conscious awareness and experiences. If we defined that “consciousness” is what the consciousness mental process creates – then “consciousness” is the composite of all conscious awareness and experiences. This is the definition of “consciousness” in this theory:
Definition. Consciousness is the composite of all conscious awareness and conscious experiences.
It should be noted that, although at any moment in a normal condition, consciousness consists of conscious awareness and experiences of several mental processes’ functions simultaneously, the intensity and accuracy of awareness and experiences of these mental processes’ functions are usually not all equal. Only one or a few mental processes’ functions have the primary conscious awareness and experiences at a time; the others have only secondary conscious awareness and experiences. The former have intense and accurate awareness and experiences while the latter have less intense and less accurate awareness and experiences. For example, when we are watching the movie, our primary conscious awareness and experiences will be on the movie-related visual perception, auditory perception, and emotion while our conscious awareness and experiences of other sensory perceptions, other emotions, time, etc. will become less intense and accurate.
Also, it is important to be aware that, in the literature, consciousness and conscious are terms that can have various meanings [2-10]. They can be used to describe different mental phenomena, such as
- a mental state of being awake and sentient (such as, he lost his consciousness in the accident and became conscious after a while),
- a mental state of being aware of something (such as, he is conscious of the girl’s presence and her scent, or he is conscious of the pain in his body),
- a mental state of being aware of and experiencing something, with the awareness of what the phenomenal characteristics are like occurring (such as consciousness is the awareness and experience of the vision, sound, emotion, and thought, with the awareness of what their phenomenal characteristics are like occurring), and
- a command center or workspace mental process that integrates other mental processes and enables them to function together (such as consciousness is the center or workspace that functions to direct attention to some signal, keep concentration on that signal, amplify and integrate that signal, and make information of that signal available to other mental processes) [11,12,13].
Neurologists and general doctors usually use the terms conscious and consciousness in the first meaning. General people usually use the terms in the second meaning. Philosophers and some neuroscientists usually discuss the terms in the third meaning, and the hard problem of consciousness [2,3,9,14,15] is the problem about consciousness in this meaning. The terms in the last meaning are used mostly by neuroscientists, and the Global Workspace theory [11,16,17,18] and the Global Neuronal Workspace theory [19,20,21] are about consciousness in this meaning also. Therefore, one should be careful what the terms mean when one reads, writes, or discuss these terms.
In this theory, similar to the third meaning above, the term consciousness will be used to mean the composite of all conscious awareness and conscious experiences (with the awareness of what the phenomenal characteristics are like occurring) because they are the only mental phenomena that differentiate sentient beings from non-sentient beings and differentiate us from artificial intelligence. Without conscious awareness and conscious experiences (with the awareness of what the phenomenal characteristics are like occurring), even the most highly integrated and very capable brain will function just like a present-day computer or robot. For other authors, the opinions may be that the term consciousness should also include some other integrative/command functions (directing attention, maintaining attention, distributing information, creating awareness of self, making decisions, etc.), but then again, the opinions may vary on how many of them and exactly which ones of them are to be included . Therefore, as the term consciousness as defined above suffices in discussions in this theory, it will be used as the working definition in this theory. This definition can be considered the minimum definition of consciousness; the wider definition is possible but not needed in this theory. And, in this theory, when the mental processes that perform the integrative/command functions are to be referred to, they will be collectively referred to as the integration-center mental process.
6.2. Consciousness neural process
As the consciousness mental process is a mental process, it cannot occur spontaneously by itself but must be part of some neural process (Theorem I). In this theory, this neural process will be called the consciousness neural process. From the properties of consciousness, it can be predicted that some important characteristics that the consciousness neural process and its circuit must have are as follows:
- It must be an extensive network that connects with all neural processes that have qualia so that conscious awareness and experiences of all the qualia are possible. These qualia neural processes are important neural processes: all external sensory perception neural processes, many internal sensory perception neural processes, all cognitive and executive neural processes (thinking, reasoning, planning, deciding, language processing, etc.), emotion neural processes, volitional movement neural processes, etc. But it is not connected to or not connected in the way that conscious awareness and experiences can occur to the lower mental processes that perform more basic functions, such as mental processes in the basal ganglia, brainstem, or cerebellum, so there are no conscious awareness and experiences of the functions of these processes.
- It must be able to read and/or synchronize with the neural processes that have qualia so that it can get information from them to process and then create the conscious awareness and experiences for these neural processes.
- It must have its signals fed back to itself so that it can be aware of the function of itself, that is, its signaling state must be a reentrant signaling state.
- Its signaling patterns must be special signaling patterns (SSPs) because the conscious awareness and conscious experiences, which form the consciousness, themselves are qualia or SSPs (i.e., conscious awareness and conscious experiences themselves have consciously experienceable phenomenal characteristics).
As far as one can conclude from the evidence at present, it seems very likely that the Default Mode Network or Resting State Network [23-28], which includes the medial prefrontal cortex, posterior cingulate cortex, precuneus, hippocampal formation, parahippocampal cortex, retrosplenial cortex, posterior inferior parietal, temporoparietal junction, and lateral temporal cortex, with the anterior medial prefrontal cortex and posterior cingulate cortex as the hubs, is the network of the consciousness neural process when the mind is not concentrating on any specific task. This network overlaps with the network of Global Workspace theory proposed by Baars [11,16,17,18] and that of Global Neuronal Workspace hypothesis of Dehaene [19,20,21], which include the cortico-thalamic (C-T) core and a network of neurons with long-range axons densely distributed in the prefrontal, fronto-parietal, parieto-temporal, and cingulate cortices. These latter two networks are found to be the consciousness neural process network when the mind is in the mode of attending to a certain stimulus. So, the complete neural network of consciousness is likely to be some form of a combination of the former networks and the latter networks, such as that proposed by Song .* It should be noted that the functions of both kinds of networks are not mutually exclusive, that is, the two kinds of networks do not work alternately in the way that one is shut off completely while the other is working. For example, when the Global Workspace or the Global Neuronal Workspace is functioning, such as when attending to a visual stimulus on a computer screen, the Resting State Network or Default Mode Network is still functioning, as is evident by the fact that the subject is still aware of the background vision, the ambient sound, one own self, etc., although the awareness of these background stimuli becomes less intense and less accurate. It is not that, while the mind is attending to something, it is not aware of anything else at all and that everything else blacks out.
(* Presently, there are several other significant theories of consciousness [11,22, 30-44] which deserve much consideration and have been instructively reviewed [45,46,47], but it is not the intention of this Theorem to discuss these theories in details.)
To be noted is that the consciousness mental process is a conscious mental process, i.e., it can be aware of and experience the function of itself. And although it appears to be of paramount importance in making us conscious, it is just one mental process among myriad other mental processes. Although it seems to be special in that it can create the mental phenomenon called consciousness (the composite of all conscious awareness and conscious experiences), other mental processes have their own special functions that are not simpler than creating consciousness, such as creating visual perception from visual stimuli, creating emotion, creating language abilities, and creating intelligence that can solve difficult mathematical problems or unravel mysteries of the universe. Physically, it is not different from other mental processes – it is just part of a neural process: the consciousness neural process. And it follows physical rules and has properties similar to those of all other mental processes, as described in section 1.1. Thus, although it is of paramount importance, it is not an exceptional mental process in any physical way.
Conscious alertness and awareness
Functionally, it has been found that the network of the consciousness neural process requires another neural network – the ascending reticular activating system (ARAS) – for its alertness or the level of its function. The ARAS is the neural network in the core of the brain extending from the rostral pons to both thalami, and from there it sends extensive axonal projections to the cerebral cortex, including the consciousness neural network [48-51]. There can be no consciousness if there is no stimulation from the ARAS, even if the consciousness neural network is intact and able to function, such as in the case of extensive brainstem hemorrhage, infarct, and trauma. And the level of conscious alertness depends on the activation from the ARAS – the more activation, the higher level of alertness. This results in various conscious states, such as (from lower to higher level of alertness) coma, stupor, drowsiness, normal alertness, and heightened alertness.
On the contrary, if the ARAS is working normally but the consciousness neural process is not, there can be alertness without, with minimal, or with some awareness. The degree of impairment of awareness depends on how much the consciousness neural process is dysfunctional. For example, in the case of damages to the consciousness neural process from diffuse cerebral hypoxia, extensive bilateral cerebral infarcts, or diffuse cerebral cortical injury, the results can be various abnormal conscious awareness states that range in severity of abnormal conscious awareness, depending on how much the consciousness neural process is impaired, such as (from mild to severe) acute confusional state, akinetic mutism, minimally conscious state (MCS), and vegetative state (VS) [52-58]. In the latter two categories, which are severe conditions, the patients can open eyes and have some reflex responses, such as blinking, chewing, and yawning, but show no (in VS) or minimal (in MCS) signs of conscious awareness of self and the environment (by clinical testing or by special investigations such as EEG, evoked potentials, fMRI, etc.) [56-62].
Both of the two kinds of variable abnormalities in consciousness show that consciousness is not an all-or-none phenomenon but is a graded phenomenon, depending on both the strength of stimulation from the ARAS and the functioning quantity of the consciousness neural process.
6.3. Theorem V
As consciousness is the composite of all conscious awareness and conscious experiences and as both conscious awareness and conscious experiences are some kinds of reentrant signaling states (see section 5.2), consciousness is the composite of all reentrant signaling states that are conscious awareness and conscious experiences. But how can some signaling states be conscious awareness and conscious experiences in the first place? To answer this question, let’s consider various signals in Figure 6.1.
Figure 6.1 Signals representing various information
In Figure 6.1A, the signal is “House”. When this signal is read, those who can read this signal will get the information of merely “House”, without anything else, such as what the house looks like. Likewise, in Figure 6.1B, the signal of the signaling pattern of a certain neural process, such as some subconscious neural process, is “House”. It may have some other subconscious information, such as the values of the size, the shape, and the color of the house, in this signaling pattern, but if it does not have the information of what the phenomenal characteristics of the house are like, other neural processes, including the consciousness neural process, that read the signal from this signaling pattern will get information of only “House” and some other information but no information of what the phenomenal characteristics of the house are like. So, the conscious awareness and experience of what the phenomenal characteristics of the house are like cannot and do not occur.
In Figure 6.1C, the signal is “House and what the house looks like”. When this signal is read, those who read the signal will get the information of “House and what the house looks like”; they will not get information of “House” alone. Likewise, in Figure 6.1D, the signal of the signaling pattern of a neural process is “House and what the house looks like”. Other neural processes that read the signal from this signaling pattern will get the information of “House and what the house looks like”. For the consciousness neural process, because of the available information and because of its specialized ability, the signaling state in Figure 6.1E that has the information of the conscious awareness and experience of the house and of what the house looks like and the conscious awareness and experience of the former conscious awareness and experience can be generated. This is how the house as it appears with all its phenomenal characteristics occurs in our minds. And, similarly, this is how all the qualia as they appear with all their phenomenal characteristics occur in our minds.
Now, the question is how can such a signaling pattern that has the information of what the phenomenal characteristics are like (such as 6.1D) and such a signaling state that has the information of the conscious awareness and experience of what the phenomenal characteristics are like and the conscious awareness and experience of the former conscious awareness and experience (such as 6.1E) be created? The answer is, because it is evident that they can be created as can be seen in billions of humans nowadays and in the past, it must be basically possible for some signaling patterns and signaling states to have such information and it must be possible for some neural processes to create such signaling patterns and signaling states. It is a brute fact.
If we consider the matter in general, it is not very surprising or improbable that these happen. There have been innumerable kinds of neural processes with myriads kind of signaling patterns and signaling states for various neural functions in various parts of the nervous system since the nervous system appeared in this world hundreds of millions of years ago: to maintain basic, vital functions, to keep various blood constituents within normal ranges, to process various kinds of sensory signals, to do diverse kinds of cognitive functions, to control the functions of different type of its effectors, and so forth. All of these need evolved specialized neural processes with specific signaling patterns and specific signaling states of their own. The quale neural processes are just neural processes with their own specific functions – to create signaling patterns that are qualia, and the consciousness neural process is just one neural process with its own specific function – to create specific signaling states that are conscious awareness and conscious experiences of qualia. It is just the fundamental nature of this universe that these are possible: some signaling patterns can be qualia, and some signaling states can be conscious awareness and conscious experiences of qualia; some neural processes can evolve to create such signaling patterns, and some neural process – the consciousness neural process – can evolve to create such signaling states.
(The physical question of “By what neural circuits and by what neural mechanisms can the consciousness neural process create conscious awareness and conscious experiences?” is being studied by many neuroscientists, and the answers are emerging, such as joint parietal-frontal-cingulate activation, cortico-cortical or thalamo-cortical γ-band oscillations, cortical neural synchronization or top-down recurrent, reentrant, or resonant activities between neural processes underlying conscious perception [50,64-74], the attractor activity in networks of pyramidal cells in the cerebral cortex [75,76,77], or the operational architectonics [78,79,80]. As the issue is very complex and lengthy, I would like to refer the readers to some of the references  that are quite revealing for more information.)
Now, reentrant signaling states also occur in other neural processes , but, unlike in the consciousness neural process, there are no conscious awareness and conscious experiences occurring in them. This means that the reentrant signaling states in the consciousness neural process must be in some special forms that are conscious awareness and conscious experiences. For conciseness, this theory will assign the term “special reentrant signaling state” to this specific kind of reentrant signaling state.
Definition. A special reentrant signaling state is a reentrant signaling state that is conscious awareness and a conscious experience.
As stated at the beginning of this section, consciousness is the composite of all reentrant signaling states that are conscious awareness and conscious experiences. But from the definition, reentrant signaling states that are conscious awareness and conscious experiences are special reentrant signaling states; therefore, the theorem for consciousness can be stated as:
Theorem V: Consciousness is the composite of all special reentrant signaling states.
Basically, however, the composite of all special reentrant signaling states is just a special kind of reentrant signaling state. Therefore, the basic form of Theorem V can be stated as:
Theorem V: Consciousness is a special kind of reentrant signaling state.
Information-wise, because any signaling state of a neural process is the information existing in that neural process, basically, consciousness is just a special kind of information existing in the consciousness neural process. This information describes conscious awareness and experiences of some things (which include the awareness of what phenomenal characteristics of those things are like) and conscious awareness and experiences of the former conscious awareness and experiences. Therefore, when the consciousness neural process reads this information by the process of reentering this information in its process, conscious awareness and experiences of those things (which include the awareness of what phenomenal characteristics of those things are like) and conscious awareness and experiences of the former conscious awareness and experiences naturally and inevitably occur in that neural process.
6.4. Effects of consciousness
Like qualia, which are proved in section 5.4 to have physical effects, consciousness has physical effects. This can be proved as follows.
Figure 6.2 Effects of integration centers without and with consciousness
Consider two integration-center mental processes in Figure 6.2. The integration-center mental process A functions to receive information from various mental processes, analyze the information, distribute appropriate information to appropriate mental processes, enhance and maintain information input from a certain mental process while suppressing information input from unrelated mental processes, etc. It may have unconscious awareness of these functions too, but it does not have conscious awareness and conscious experiences of these functions, with the awareness of what the phenomenal characteristics of these functions are like occurring – i.e., it does not have consciousness – in its operations, like the cerebellum or present-day computers.
On the other hand, the integration-center mental process B performs the identical functions, but in addition, it has conscious awareness and conscious experiences of these functions, with the awareness of what the phenomenal characteristics of these functions are like occurring – i.e., it has consciousness – in its operations. As these two mental processes involve different information, they require different signaling patterns and different signaling states in their neural processes. Consequently, the physical characteristics of the two neural processes and their physical effects on other neural processes must be different, at least because of their differences in different signaling patterns and different signaling states.
So, the integration center without consciousness will have different effects from the one with consciousness. At present, there is not enough evidence to state conclusively what these different effects are. But as evolving the integration center by adding a new feature (in this case, consciousness) must cost a being some resources (material to build the circuit, energy to maintain the process, time to handle additional signals, etc.), if the new feature (in this case, consciousness) does not yield any benefits to the being, it will be a disadvantage for that being. This will be true for its species as a whole. Its species will likely be losing from this disadvantage and will become extinct in competition with the species that are similar but do not have consciousness. But this kind of extinction has not happened to human beings, who definitely possess consciousness, and to many high-level animal species that probably have consciousness [81-88]. On the contrary, these species seem to be thriving and dominating in the evolutionary process. Therefore, it can be deduced that consciousness must yield some beneficial effects to the beings that possess it. Similar to the effects of qualia on perception, it is probable that consciousness augments the functions of the integration-center mental process to become more effective .
6.4.1. But why does it have to be consciousness to gain these augmenting effects?
This question is similar to the one regarding qualia, which has been answered in section 5.4.1. The answer in the case of consciousness will be very similar. It will be repeated here again with some modifications and in an abridged form. (If already content with the answer in section 5.4.1., the reader may just as well skip the next three paragraphs to the next question.)
Before the augmentation of the nervous system functions by creating consciousness emerged, the nervous system had been augmenting its functions with other means all along since it appeared on this planet – by developing a more and more complex and more and more capable nervous system – notwithstanding the absence or presence of consciousness. Even after consciousness had emerged, other parts of the cerebral cortex that functioned without consciousness occurring in their processes did not stop evolving: they have been continuing to evolve to be more complex and more capable , resulting in higher intelligence, more language facilities, more manual skill abilities, etc. Even the cerebellum and other parts of the brain have proved to continue to co-evolve with the cerebral cortex [91,92,93] (which is the seat of consciousness) all the time, even if they do not have consciousness.
Creation of consciousness is just one possible path in the nervous system evolution. Consciousness emerged in this world simply because, at a certain stage in the nervous system evolution, it was possible – the neural processes were advanced enough to evolve the new kind of neural processes that was capable of creating consciousness. After consciousness began to appear in this world, it has been selected to persist up to the present time possibly because it yields some advantages to the animals that possess it. That is why today it still exists in humans and probably in some other animals too [81-88]. And consciousness emerged because of no other cause than evolution; that is why it took more than two billion years after life had appeared on earth and hundreds of millions of years after the nervous system had emerged before it could evolve into existence.
It remains to be seen whether creating consciousness is the end of this evolutionary path or whether neural processes with consciousness can evolve further into new kinds of neural processes with new capabilities that are even more phenomenal than consciousness. To augment its functions, the nervous system has been evolving many kinds of neural processes, signaling patterns, and signaling states all along. The generation of consciousness is thus not the necessary path, the most effective path, or the final path, but just one possible path, in augmenting the nervous system functions.
6.4.2. Then, why not augment all mental processes with consciousness? Why augment only some mental processes?
This question is similar to the question regarding qualia in section 5.4.2.; the answer in the case of consciousness will also be similar.
The cerebral cortex has evolved to be a broadly adaptable system that does not depend on fixed hardwiring of neural circuits alone but is also able to make use of information gathering and information processing: gathering encountered information, extracting the essence of each information, storing it, retrieving it, and dealing with it cognitively (i.e. by processes of forming possible scenarios, retrieving experiences in the past, comparing available choices, using rules that have been learned, etc.). But this system requires an integration center that can coordinate signal communications between several cortical areas: those involved in the final-stage perceptions of all external sensations and some internal sensations, cognitive perceptions (of space, time, self, non-self, etc.), other cognitive and executive functions (thinking, recalling past events, planning, deciding, language processing, etc.), emotion, and volitional motor control. It can certainly operate without consciousness, as is evident by the fact that the computer and the cerebellum can also do this kind of integrations without consciousness, but as shown at the beginning of this section, the integration center without consciousness has different effects from the one with consciousness, with the one with consciousness has potentials to add something beneficial to the system. Thus, creating consciousness in such a vital system, with conscious awareness and experiences of all important mental processes, can yield critical advantages to the organism. It can enhance perception, cognition, emotion, memory functions, volitional motor functions, etc. It is likely that, because perceiving the situation in the outside world correctly, analyzing them and forming responses to them effectively, and executing purposive motor movement appropriately are the most crucial mental functions of the being, it is beneficial and advantageous to augment the mental processes that perform these crucial functions with a novel function: consciousness. This is why consciousness evolved to occur in these mental processes and this is why some mental processes have consciousness while some do not – consciousness in some mental processes is beneficial and can yield advantages while consciousness in some mental processes is unnecessary and can create disadvantages.
6.5. The hard problem of consciousness
The hard problem of consciousness [2,3,14,15,65,94,95] can be answered similarly to that of qualia (see section 5.5) because consciousness itself is just another form of qualia (consciousness itself has consciously experienceable phenomenal characteristics). The hard problem of consciousness is basically the hard problem of its being a quale: why does consciousness have consciously experienceable phenomenal characteristics – why cannot it be without consciously experienceable phenomenal characteristics, like the unconscious awareness and experiences in the electronic brains of the present-day robots? These questions are not expected to be answered by scientific experiments alone. On the contrary, other aspects of consciousness, such as what the exact neural circuit that can function to create consciousness is, are “not hard” in the sense that they can theoretically be found out eventually by scientific investigations. Without having a quale, the consciousness neural process is just a complex neural process that is not functionally different from complex integrated circuits of computers or robots nowadays.
6.5.1. What is consciousness?
As discussed in 6.3., consciousness is a special kind of information existing in the consciousness neural process. This information describes conscious awareness and experiences (which include the awareness of what phenomenal characteristics are like) of some things and conscious awareness and experiences of the former conscious awareness and experiences. Therefore, when the consciousness neural process reads this information by the process of reentering this information in its process, conscious awareness and experiences (which include the awareness of what phenomenal characteristics are like) of some things and conscious awareness and experiences of the former conscious awareness and experiences naturally and inevitably occur in that neural process.
Physically, consciousness is a special kind of reentrant signaling state: a composite of all special reentrant signaling states. This composite is itself the consciousness (the information discussed above) – nothing else is created to be the consciousness. Thus, the consciousness is an intrinsically occurring entity in, not an entity that occurs separately and additionally to, the consciousness neural process. It is an informational entity like the mind and mental processes and is categorically different from conventional physical entities (mechanical entities) like mass, energy, and force.
6.5.2. Why does consciousness exist?
Consciousness – conscious awareness and experiences (with the awareness of what the phenomenal characteristics are like) – exists in this universe because it is fundamentally possible to have conscious awareness and experiences in this universe. And it exists in the nervous system – in the composite of all special reentrant signaling states – because, in this universe, it is fundamental in the nature of neural signaling states that some kinds of neural signaling states are conscious awareness and experiences and that the composite of them is consciousness. As discussed before, it is a brute fact.
6.5.3. Why does consciousness occur?
Consciousness occurred because, at some evolutionary stage about 520 – 315 million years ago (see the footnote on page 80), it was possible for the nervous system, which was advanced enough then, to evolve new kinds of neural processes that were capable of creating qualia and conscious awareness and experiences. Thus, consciousness occurred simply because it was evolutionarily possible for it to occur.
Consciousness still occurs today because there are neural processes that are capable of producing it functioning. Evidently, that these kinds of neural processes still exist today means that they have been preserved in the evolutionary process since they appeared in this world. This, in turn, indicates that the consciousness, which these kinds of neural processes produce, must yield some effects that increase the chance of survival of the species that possess it. Thus, consciousness still occurs today because it must somehow help increase the chance of survival of the species that possess it.
6.5.4. How does consciousness occur?
Consciousness occurs by the functioning of a specific neural process (the consciousness neural process). Specifically, consciousness occurs by this neural process creating a specific signaling state: the composite of all special reentrant signaling states. This signaling state is the consciousness – no additional entity occurs to be the consciousness.
6.5.5. When does consciousness occur?
As discussed in 6.5.3., consciousness occurred in this world around 520 – 315 million years ago when the nervous system was advanced enough to evolve the neural process that was able to produce the composite of all special reentrant signaling states. This neural process is the consciousness neural process. After that, consciousness occurs whenever the consciousness neural process produces this composite.
6.5.6. Why can there not be just nervous systems without consciousness?
There can be just nervous systems without consciousness, and this had been the case for a long time – hundreds of millions of years – since the nervous system had appeared on this planet to the time when evolving neural processes became advanced enough to produce conscious awareness and experiences. When that time came, consciousness emerged simply because it was possible. It is only after that time that there are nervous systems with consciousness.
6.5.7. Why can the consciousness neural process not produce conscious awareness and experiences but still preserves the same particular effects?
Because it cannot do that – those particular effects result from the conscious awareness and experiences themselves. When the consciousness neural process produces the conscious awareness and experience of something, with the awareness of what the phenomenal characteristics of that thing are like occurring, it creates a certain reentrant signaling state – a special reentrant signaling state – which is the conscious awareness and experience of that thing. This specific reentrant signaling state (the special reentrant signaling state) is what that yields those particular effects to other neural processes (Figure 6.3A).
Figure 6.3. Consciousness with and without a special reentrant signaling state (SP = Signaling pattern)
Therefore, the consciousness neural process cannot have those particular effects without creating this specific signaling state, that is, without producing the conscious awareness and experience (Figure 6.3B). Even if it produces the unconscious awareness and experience of the same thing (i.e., the awareness and experience of that thing without the awareness of what the phenomenal characteristics of that thing are like occurring), the signaling state and its effects will be different.
In conclusion, consciousness, as it is (i.e., conscious awareness and experiences, with awareness of what the phenomenal characteristics are like occurring), occurs in the nervous system because, in this form, it has particular effects on the nervous system and thus has particular functions in the nervous system. If it were not in this form (i.e., without awareness of what the phenomenal characteristics are like occurring), these particular effects and functions would not occur.
6.6. Consciousness in other beings, other entities, or other mental states
6.6.1. Do animals have consciousness?
Because similar neural processes have similar signaling states and because consciousness is just a kind of signaling state, any animals that have similar consciousness neural processes to ours have similar signaling states and thus should have similar consciousness to ours. Animals that have fairly similar brain structures and neural processes to ours, such as mammals (chimpanzees, elephants, dolphins, dogs, etc.), are likely to have fairly similar consciousness to ours. Animals that have less similar brain structures and neural processes to ours, such as reptiles or amphibians (crocodiles, frogs, etc.), are likely to have less similar consciousness to ours. Animals that have very different brain structures and neural processes from ours, such as arthropods (ants, bees, flies, etc.) or cephalopods (octopus, squid, nautilus, etc.), may have different kinds of consciousness from ours [47,86-88]. This can be definitely answered if the kind of neural circuits and signaling states that create consciousness in humans and the probable consciousness neural circuits and their signaling states in other animals can be identified and compared.
6.6.2. Do computers and robots have consciousness?
As computers and robots have parts that function similarly to parts of the nervous system of animals – sensors (mouse, keyboard, camera, microphone, etc.), central processor and controller (computer motherboard, robot mainboard, etc.), and effectors (display monitor, speaker, robotic arm, etc.) – and as they use electrical signals in processing and communicating information between these parts and thus have electrical signals representing various kinds of information circulating in their circuits, it is logical to speculate that there might be phenomenal characteristics (like the red color or the sound of note C in our mind) occurring in their systems because some of their signaling patterns might have phenomenal characteristics as some of human neural processes’ signaling patterns (such as the special signaling patterns) do. At present, it cannot be answered definitely whether there are phenomenal characteristics occurring in their signaling processes because we still do not know what kind of signaling patterns can be phenomenal characteristics.
However, if phenomenal characteristics do occur in the computers and/or robots, they definitely have no physical effects on any of their circuits because, evidently, all their circuits still work in the expected way that they are designed to do. It has never been found that the circuits in the computers and robots do any operations that are not pre-designed in them. And it is definite that present-day computers and robots do not and cannot have conscious awareness and experiences of phenomenal characteristics that may occur in them. This is because conscious awareness and experiences of phenomenal characteristics are additional functions and have additional information. So, computers and robots need specific, dedicated circuits to perform these specific functions and manage the new information that occurs in the process. But there are no such circuits in the present-day computers and robots; all the circuits in their motherboards or mainboards are built to do some specific tasks else that are already predefined, such as the summation of two digits, the computation of transcendental functions of some digits, and the generation of signals to control other parts: screen monitor, disc drive, mechanical motor, etc. None is built to be aware of and experience phenomenal characteristics that may occur in their circuits, and none is built to be aware of and experience something with the awareness of what that thing’s phenomenal characteristics are like occurring. (At present, we do not know how to build such consciousness-generating circuits.) Therefore, it is definite that present-day computers and robots do not and cannot have conscious awareness and experiences of anything, that is, they do not and cannot have consciousness. Similarly, this conclusion is true for all other present-day electronic devices or any device that processes information: a thermometer, a mobile phone, an industrial robot, an automated industrial machine, etc. This is in agreement with some theories of consciousness such as Integrated information theory (IIT) [96-98].
How do we build computers or robots that have consciousness as we do?
As discussed above, to have consciousness as we do, computers and robots must have conscious awareness and experiences with awareness of what phenomenal characteristics are like occurring in their circuits. But to have such awareness and experiences needs specifically arranged circuits with specifically patterned processes. Therefore, no matter how complex the circuits are, if they do have such specific characteristics, they will not be able to create consciousness like the one that occurs in us (i.e., complexity is not the determining factor whether consciousness will occur, but specificity is).
Although some principal characteristics of a neural circuit that can generate human-kind consciousness are obvious, as outlined in section 6.2., the exact details of the circuit that can create such conscious awareness and experiences are not yet known at present. Theoretically, if they are known and if the possibility of having consciousness is not restricted to only biological processes but extends to electronic processes, then computers and robots that have consciousness can be built. This is in accordance with the principle of organizational invariance of Chalmers . And some theories of consciousness, such as Integrated information theory (IIT) [96-98], have already proposed interesting ideas about these kinds of consciousness.
Can we build robots or can there be automatons that behave identically to us but that do not have qualia and consciousness?
If they do not have qualia and consciousness, they cannot behave identically to us because the lack of conscious awareness and experiences of qualia will cause the lack of information of these phenomena. Therefore, they will not be able to behave identically to us in the activities that depend on or are related to this kind of information because they do not know what behaviors are to be generated, such as to answer the question of “Are there extra phenomena occurring in your perception of the red color compared with your perception of the level of your metabolism?”. It is obvious that their answers will be “no”, which is different from our answer “yes”, because for them, no extra phenomena occur in the perception of the red color.
Can we build robots or can there be automatons that have signals circulating in their brains identical to those circulating in our brains but that do not have qualia and consciousness?
The answer is no. If the all circulating signals are identical, then there must be signals that are qualia and conscious awareness and experiences of the qualia occurring in their brains. If there are such signals occurring in their brains, then it is unavoidable that qualia and conscious awareness and experiences of the qualia are to occur in their brains because such signals themselves are qualia and conscious awareness and experiences of the qualia.
The ultimate question related to this issue is whether it is basically possible to build electronic circuits that have circulating signals identical to those in our brains: are there some fundamental differences (between neural circuits and electronic circuits) that we do not know of yet prohibiting such imitations? The same question is true for other circuits that are not neural circuits.
6.6.3. When we are asleep in NREM stages, under general anesthesia, or in a deep coma, do we have consciousness?
Obviously, under those conditions, the consciousness neural process is not functioning at the alert level, and there is no signaling state that signals alert consciousness; thus, there is no alert consciousness in such conditions. However, although the consciousness neural process is not functioning to produce alert consciousness, it is not dead and is still functioning at the sleep or depressed level. So, the consciousness does not completely disappear. Also, the state of no alert-consciousness will be only temporary if there is no fatal condition involved. The alert consciousness will return after those conditions disappear. So, physiologically, consciousness can function at various levels, not only at the alert level, and it can be considered that we still have consciousness, but not at the alert level, when we are asleep in NREM stages, under general anesthesia, or in a deep coma.
6.6.4. When does consciousness appear in a being?
Consciousness does not come suddenly once the brain begins to form in a fetus, nor does it come when an infant is born. As consciousness occurs with the consciousness neural process, it will appear when the consciousness neural process begins to function. Obviously, the mature consciousness cannot appear all of a sudden in the fetus but develops gradually as the consciousness neural circuit and process mature little by little. This is similarly true for a person who slowly wakes up from sleep or gradually recovers from general anesthesia, cerebral concussion, hypoglycemia, etc. – consciousness returns gradually, not reappears suddenly like a light bulb that suddenly lights up when switched on. The consciousness neural process functions not in an all-or-none manner but in various graded levels, as discussed previously, so does the consciousness, which occurs with the consciousness neural process.
- Consciousness (conscious awareness and experiences) can be identified, quantified, monitored, created, modified, tested, or destroyed by performing the respective action on only the composite of all special reentrant signaling states. The actions on the composite are both necessary and sufficient for the corresponding actions on the consciousness to occur, and these actions on anything else without having the actions on the composite will not result in the corresponding actions on the consciousness.
- In any event or experiment, all predictions that are valid for the composite of all special reentrant signaling states, such as that the composite will occur, change, or disappear, will be valid for the consciousness, and the changes that occur in the composite and that occur in the consciousness will be identical in all aspects (quality, quantity, temporal pattern, etc.). For example, if the composite of all special reentrant signaling states changes abruptly from the composite of special reentrant signaling states of vision, hearing, and thinking to the composite of special reentrant signaling state of only emotion, the changes in the consciousness will be identical in all aspects, such as identical changes from conscious awareness and experiences of vision, hearing, and thinking to those of only emotion (quality), from the composite of three signaling states to the composite of one signaling state (quantity), and abruptly (temporal pattern).
- Regarding the consciousness neural process, it will be found that the consciousness neural process has connections to all neural processes that have qualia, that it has its signals fed back to itself, and that it has the signaling pattern that is special signaling pattern when it functions to be consciously aware of and experience something.
- Dehaene S, Changeux JP, Naccache L, Sackur J, Sergent C. Conscious, preconscious, and subliminal processing: A testable taxonomy. Trends Cogn Sci. 2006 May;10(5):204-211. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.65.3821&rep=rep1&type=pdf
- Chalmers DJ. Facing up to the problem of consciousness. J Conscious Stud. 1995;2(3):200-219. http://consc.net/papers/facing.html
- Chalmers DJ. Moving forward on the problem of consciousness. J Conscious Stud. 1997;4(1):3-46. http://consc.net/papers/moving.html
- Chalmers DJ. Consciousness and its place in nature. In: Chalmers DJ, editor. Philosophy of mind: Classical and contemporary readings. Oxford: Oxford University Press; 2002. ISBN-13: 978-0195145816 ISBN-10: 019514581X. Retrieved 2017 Sep 20 from http://consc.net/papers/nature.html
- De Sousa A. Towards an integrative theory of consciousness: Part 1 (neurobiological and cognitive models). Mens Sana Monogr. 2013 Jan-Dec;11(1):100–150. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3653219/
- Gennaro RJ. Consciousness. Internet Encyclopedia of Philosophy. Retrieved 2017 Apr 18 from http://www.iep.utm.edu/consciou/
- Rosenthal D. Concepts and definitions of consciousness. 2015 Jul. doi: 10.1016/B978-012373873-8.00018-9. Retrieved 2017 Sep 20 from https://www.researchgate.net/publication/280529005_Concepts_and_Definitions_of_Consciousness_in_Encyclopedia_of_Consciousness_ed_William_P_Banks_Amsterdam_Elsevier_2009_pp_157-169
- Sturm T. Consciousness regained? Philosophical arguments for and against reductive physicalism. Dialogues Clin Neurosci. 2012 Mar;14(1):55–63. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3341650/
- Van Gulick R. Consciousness. Zalta EN, editor. The Stanford Encyclopedia of Philosophy (Summer 2017 Edition). Retrieved 2017 Sep 8 from https://plato.stanford.edu/archives/sum2017/entries/consciousness
- Zeman A. Consciousness. Brain. 2001 Jul;124(Pt 7):1263-1289. https://academic.oup.com/brain/article-pdf/124/7/1263/802709/1241263.pdf
- Baars BJ. Chapter Ten. The functions of consciousness. In: A cognitive theory of consciousness. NY: Cambridge University Press; 1988. Retrieved 2017 Aug 5 from http://bernardbaars.pbworks.com/f/++++Functions+of+Consciousness.pdf
- Prakash R. The conscious access hypothesis: Explaining the consciousness. Indian J Psychiatry. 2008 Jan-Mar;50(1):10–15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2745874/
- Rosenthal D. Concepts and definitions of consciousness. 2015 Jul. doi: 10.1016/B978-012373873-8.00018-9. Retrieved 2017 Sep 20 from https://www.researchgate.net/publication/280529005_Concepts_and_Definitions_of_Consciousness_in_Encyclopedia_of_Consciousness_ed_William_P_Banks_Amsterdam_Elsevier_2009_pp_157-169
- Grossberg S. Towards solving the hard problem of consciousness: The varieties of brain resonances and the conscious experiences that they support. Neural Netw. 2017 Mar;87:38-95. https://linkinghub.elsevier.com/retrieve/pii/S0893-6080(16)30180-0
- Weisberg J. The hard problem of consciousness. The Internet Encyclopedia of Philosophy. Retrieved 2018 Jan 29 from https://www.iep.utm.edu/hard-con/
- Baars BJ. How does a serial, integrated and very limited stream of consciousness emerge from a nervous system that is mostly unconscious, distributed, parallel and of enormous capacity? Ciba Found Symp. 1993;174:282-290;discussion 291-303
- Baars BJ. Global workspace theory of consciousness: Toward a cognitive neuroscience of human experience. Prog Brain Res. 2005;150:45-53. https://www.cs.helsinki.fi/u/ahyvarin/teaching/niseminar4/Baars2004.pdf
- Baars BJ, Franklin S, Ramsoy TZ. Global workspace dynamics: Cortical “Binding and propagation” enables conscious contents. Front Psychol. 2013;4:200. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3664777/
- Dehaene S, Naccache L. Towards a cognitive neuroscience of consciousness: Basic evidence and a workspace framework. Cognition. 2001 Apr;79(1-2):1-37. https://www.jsmf.org/meetings/2003/nov/Dehaene_Cognition_2001.pdf
- Dehaene S, Changeux JP. Experimental and theoretical approaches to conscious processing. Neuron. 2011 Apr;70(2):200-227. https://www.sciencedirect.com/science/article/pii/S0896627311002583
- Sergent C, Dehaene S. Neural processes underlying conscious perception: experimental findings and a global neuronal workspace framework. J Physiol Paris. 2004 Jul-Nov;98(4-6):374-384. https://pdfs.semanticscholar.org/ae61/178a998b4e08851af8ba80e7815fd2c9e6d9.pdf
- Velmans M. How to define consciousness – and how not to define consciousness. J Conscious Stud. 2009;16(5):139-156. http://cogprints.org/6453/1/How_to_define_consciousness.pdf
- Andrews-Hanna JR. The brain’s default network and its adaptive role in internal mentation. Neuroscientist. 2012 Jun;18(3):251–270. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553600/
- Buckner RL, Andrews-Hanna JR, Schacter DL. The brain’s default network: anatomy, function, and relevance to disease. Ann N Y Acad Sci. 2008 Mar;1124:1-38. http://www.nslc.wustl.edu/courses/Bio3411/woolsey/Readings/Lecture11/Buckner et al 2008.pdf
- Calster LV, D’Argembeau A, Salmon E, Peters F, Majerus S. Fluctuations of attentional networks and default mode network during the resting state reflect variations in cognitive states: Evidence from a novel resting-state experience sampling method. Journal of Cognitive Neuroscience. 2017 Jan;29(1):95-113. http://www.mitpressjournals.org/doi/full/10.1162/jocn_a_01025
- Hagmann P, Cammoun L, Gigandet X, Meuli R, Honey CJ, Wedeen VJ, et al. Mapping the structural core of human cerebral cortex. doi: https://doi.org/10.1371/journal.pbio.0060159. Retrieved 2017 Aug 18 from http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0060159
- Raichle ME, MacLeod AM, Snyder AZ, Powers WJ, Gusnard DA, Shulman GL. A default mode of brain function. Proc Natl Acad Sci U S A. 2001 Jan;98(2):676–682. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC14647/
- Sporns O. Structure and function of complex brain networks. Dialogues Clin Neurosci. 2013 Sep;15(3):247–262. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3811098/
- Song X, Tang X. An extended theory of global workspace of consciousness. Progress in Natural Science. 2008 Jul;18(7):789–793. https://www.sciencedirect.com/science/article/pii/S100200710800138X
- Edelman GM. The Remembered Present: A Biological Theory of Consciousness. New York, NY: Basic Books; 1989.
- Edelman G, Tononi G. A Universe of consciousness: How matter becomes imagination. New York: Basic Books; 2001. ISBN-13: 9780465013777 ISBN-10: 0465013775
- Edelman GM, Gally JA, Baars BJ. Biology of Consciousness. Front Psychol. 2011;2:4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111444/
- Graziano MSA. Consciousness and the social brain. New York, NY: Oxford University Press; 2015. ISBN 978-0-19-026319-5.
- Graziano MSA,Webb TW. The attention schema theory: A mechanistic account of subjective awareness. Front Psychol. 2015;6:500. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4407481/
- Grossberg S. Adaptive Resonance Theory: how a brain learns to consciously attend, learn, and recognize a changing world. Neural Netw. 2013 Jan;37:1-47.
- Llinás R, Ribary U, Contreras D, Pedroarena C. The neuronal basis for consciousness. Philos Trans R Soc Lond B Biol Sci. 1998 Nov;353(1377):1841–1849. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692417/pdf/9854256.pdf
- McFadden J. The Conscious Electromagnetic Information (Cemi) Field Theory.The hard problem made easy? J Conscious Stud. 2001;9(8):45–60. https://philpapers.org/archive/MCFTCE.pdf
- McFadden J. The CEMI Field Theory gestalt information and the meaning of meaning. J Conscious Stud. 2013;20 (3-4):3-4. https://philpapers.org/rec/MCFTCF-2
- Min BK. A thalamic reticular networking model of consciousness. Theor Biol Med Model. 2010;7:10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857829/
- Newman J, Baars BJ, Cho SB. A neural global workspace model for conscious attention. Neural Networks. 1997;10(7):1195–1206. http://ccrg.cs.memphis.edu/assets/papers/1997/Newman%20Baars%201997.pdf
- Rosenthal D. M. (2005). Consciousness and Mind. Oxford: Oxford University Press.
- Tononi G. An information integration theory of consciousness. BMC Neurosci 2004,5:42. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC543470/pdf/1471-2202-5-42.pdf
- Tononi G. Consciousness, information integration, and the brain. Prog Brain Res. 2005;150:109-126. http://www.brainnrg.org/files/publicationmodule/@random4824abb32cfea/Tononi_2005_Progress_in_Brain_Research.pdf
- Ward LM. The thalamic dynamic core theory of conscious experience. Conscious Cogn. 2011 Jun;20(2):464-486. http://scholar.google.co.th/scholar_url?url=https://www.researchgate.net/profile/Lawrence_Ward/publication/50195797_The_thalamic_dynamic_core_theory_of_conscious_experience/links/0fcfd50a2e45c0a448000000.pdf&hl=th&sa=X&scisig=AAGBfm2HLr3DtRYSfNB-YD09l_I7gVCfXQ&nossl=1&oi=scholarr&ved=0ahUKEwiW0OaOg9_aAhWKULwKHccVBUMQgAMIJSgAMAA
- Block N. Comparing the major theories of consciousness. In: Gazzaniga MS, editor. The Cognitive Neurosciences (Chap 77). 4th ed., Cambridge, MA: MIT Press; 2009:1111–1122. https://www.nyu.edu/gsas/dept/philo/faculty/block/papers/Theories_of_Consciousness.pdf
- Seager W. Theories of consciousness.An introduction and assessment. 2nd ed. New York, NY: Routledge; 2016. ISBN 978-0-415-83409-4.
- Baars BJ. Subjective experience is probably not limited to humans: The evidence from neurobiology and behavior. Conscious Cogn. 2005 Mar;14(1):7-21.
- Fuller PM, Sherman D, Pedersen NP, Saper CB, Lu J. Reassessment of the structural basis of the ascending arousal system. J Comp Neurol. 2011 Apr;519(5):933–956. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3119596/
- Reinoso-Suárez F, de Andrés I, Garzón M. Functional anatomy of the sleep-wakefulness cycle: Wakefulness. Adv Anat Embryol Cell Biol. 2011;208:1-128.
- Seth AK, Baars BJ. Neural Darwinism and consciousness. Conscious Cogn. 2005 Mar;14(1):140-168. https://s3.amazonaws.com/academia.edu.documents/1255159/3iia_Seth___Baars__Neural_Darwinism.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1524993388&Signature=T80Czqdts7AS26uBWOxgOWYsmeU%3D&response-content-disposition=inline%3B%20filename%3DAnil_Seth_and_Bernard_Baars_Neural_Darwi.pdf
- Yeo SS, Chang PH, Jang SH. The ascending reticular activating system from pontine reticular formation to the thalamus in the human brain. Front Hum Neurosci. 2013;7:416. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3722571/
- Bernat JL. Chronic disorders of consciousness. Lancet 2006;367:1181–1192. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.330.3843&rep=rep1&type=pdf
- Bernat JL. Chronic consciousness disorders. Annu Rev Med. 2009;60:381-392.
- Giacino JT, Ashwal S, Childs N, Cranford R, Jennett B, et al. The minimally conscious state: Definition and diagnostic criteria. Neurology. 2002 Feb 12;58(3):349-353. http://n.neurology.org/content/58/3/349.long
- Hodelín-Tablada R. Minimally conscious state: Evolution of concept, diagnosis and treatment. MEDICC Review. 2016 Oct;18(4):43–46. http://www.medicc.org/mediccreview/index.php?issue=41&id=566&a=vahtml
- Perri CD, Thibaut A, Heine L, Soddu A, Demertzi A, Laureys S. Measuring consciousness in coma and related states. World J Radiol. 2014 Aug;6(8):589–597. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4147439/
- Bender A, Jox RJ, Grill E, Straube A, Lulé D. Persistent vegetative state and minimally conscious state. A systematic review and meta-analysis of diagnostic procedures. Dtsch Arztebl Int. 2015 Apr;112(14):235–242. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4413244/
- Bruno MA, Vanhaudenhuyse A, Thibaut A, Moonen G, Laureys S. From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: Recent advances in our understanding of disorders of consciousness. J Neurol. 2011 Jul;258(7):1373-1384. http://www.academia.edu/9792867/From_unresponsive_wakefulness_to_minimally_conscious_PLUS_and_functional_locked-in_syndromes_recent_advances_in_our_understanding_of_disorders_of_consciousness
- Cavanna AE, Cavanna SL, Servo S, Monaco F. The neural correlates of impaired consciousness in coma and unresponsive states. Discov Med. 2010 May;9(48):431-438. http://www.discoverymedicine.com/Andrea-Eugenio-Cavanna/2010/05/09/the-neural-correlates-of-impaired-consciousness-in-coma-and-unresponsive-states/
- Giacino JT. The minimally conscious state: Defining the borders of consciousness. Prog Brain Res. 2005;150:381-395.
- Gosseries O, Bruno MA, Chatelle C, Vanhaudenhuyse A, Schnakers C, Soddu A, et al. Disorders of consciousness: What’s in a name? NeuroRehabilitation. 2011;28(1):3-14. https://pdfs.semanticscholar.org/d8fd/17167b0fc2fb4ef7bb7b39828e1cfe1a8255.pdf
- Hirschberg R, Giacino JT. The vegetative and minimally conscious states: Diagnosis, prognosis and treatment. Neurol Clin. 2011 Nov;29(4):773-786. https://www.researchgate.net/profile/Joseph_Giacino/publication/255971880_Hirschberg_Giacino_VS_MCS_Dx_Px_Tx_Neurol_Clinics_2011/links/0c9605212e924b0a19000000/Hirschberg-Giacino-VS-MCS-Dx-Px-Tx-Neurol-Clinics-2011.pdf
- Edelman GM, Gally JA. Reentry: A key mechanism for integration of brain function. Front Integr Neurosci. 2013;7:63. doi: 10.3389/fnint.2013.00063. PMCID: PMC3753453. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753453/
- Babiloni C, Marzano N, Soricelli A, Cordone S, Millán–Calenti JC, Percio CD, Buján A. Cortical neural synchronization underlies primary visual consciousness of qualia: Evidence from event–related potentials. Front Hum Neurosci. 2016;10:310. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4927634/
- Brogaard B, Gatzia DE. What can neuroscience tell us about the hard problem of consciousness? Front Neurosci. 2016;10:395. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5013033/
- Buzsáki G. Neural syntax: Cell assemblies, synapsembles and readers. Neuron. 2010 Nov;68(3):362–385. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3005627/
- Dehaene S, Sergent C, Changeux JP. A neuronal network model linking subjective reports and objective physiological data during conscious perception. Proc Natl Acad Sci U S A. 2003 Jul 8;100(14):8520–8525. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC166261/
- Edelman GM. Neural Darwinism: Selection and reentrant signaling in higher brain function. Neuron. 1993 Feb;10:115-125. http://brainmaps.org/pdf/edelman1993.pdf
- Edelman GM, Gally JA. Reentry: A key mechanism for integration of brain function. Front Integr Neurosci. 2013;7:63. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753453/
- Engel AK, Singer W. Temporal binding and the neural correlates of sensory awareness. Trends in Cognitive Science. 2001 Jan;5(1):16-25. http://andreas-engel.com/engel_2001_tics.pdf
- Fisch L, Privman E, Ramot M, Harel M, Nir Y, Kipervasser S, et al. Neural “Ignition”: Enhanced activation linked to perceptual awareness in human ventral stream visual cortex. Neuron. 2009 Nov 25;64(4):562–574. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854160/
- Martinovic J, Busch NA. High frequency oscillations as a correlate of visual perception. Int J Psychophysiol. 2011 Jan;79(1):32-38.
- Pollen DA. On the neural correlates of visual perception. Cereb Cortex. 1999;9(1):4-19.
- van Gaal S, Lamme VA. Unconscious high-level information processing: Implication for neurobiological theories of consciousness. Neuroscientist. 2012 Jun;18(3):287-301. http://journals.sagepub.com/doi/pdf/10.1177/1073858411404079
- Orpwood R. Neurobiological mechanisms underlying qualia. J Integr Neurosci. 2007 Dec;6(4):523-540.
- Orpwood RD. Perceptual qualia and local network behavior in the cerebral cortex. J Integr Neurosci. 2010 Jun;9(2):123-152.
- Orpwood R. Qualia could arise from information processing in local cortical networks. Front Psychol. 2013;4:121. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3596736/
- Fingelkurts AA, Fingelkurts AA. Operational architectonics of the human brain biopotential field – Towards solving the mind-brain Problem. Brain and Mind. 2001;2(3):261-296. https://www.bm-science.com/team/art18.pdf
- Fingelkurts AA, Fingelkurts AA, Neves CFH. Phenomenological architecture of a mind and operational architectonics of the brain: The unified metastable continuum. New mathematics and natural computation. 2009;5(1):2212-2244. https://www.bm-science.com/team/art53.pdf
- Fingelkurts AA, Fingelkurts AA, Neves CFH. Consciousness as a phenomenon in the operational architectonics of brain organization: Criticality and self-organization considerations. Chaos, Solitons & Fractals. 2013 Oct;55:13-31.
- Boly M, Seth AK, Wilke M, Ingmundson P, Baars B, Laureys S, et al. Consciousness in humans and non-human animals: Recent advances and future directions. Front Psychol. 2013;4:625. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3814086/
- Butler AB, Manger PR, Lindahl BI, Arhem P. Evolution of the neural basis of consciousness: A bird-mammal comparison. Bioessays. 2005 Sep;27(9):923-936.
- Butler AB. Evolution of brains, cognition, and consciousness. Brain Res Bull. 2008 Mar 18;75(2-4):442-449.
- Edelman DB, Baars BJ, Seth AK. Identifying hallmarks of consciousness in non-mammalian species. Conscious Cogn. 2005 Mar;14(1):169-187. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.83.4676&rep=rep1&type=pdf
- Edelman DB, Seth AK. Animal consciousness: A synthetic approach. Trends Neurosci. 2009 Sep;32(9):476-484.
- Low P. The Cambridge declaration on consciousness. Panksepp J, Reiss D, Edelman D, Van Swinderen B, Low P, Koch C, editors. Publicly proclaimed in Cambridge, UK, on July 7, 2012, at the Francis Crick Memorial Conference on Consciousness in Human and non-Human Animals. http://fcmconference.org/img/CambridgeDeclarationOnConsciousness.pdf
- Mather JA. Cephalopod consciousness: Behavioural evidence. Conscious Cogn. 2008 Mar;17(1):37-48.
- Panksepp J. Cross-Species affective neuroscience decoding of the primal affective experiences of humans and related animals. Sirigu A, editor. PLoS ONE. 2011 Sep;6(9):e21236. https://doi.org/10.1371/journal.pone.0021236 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0021236
- Mudrik L, Faivre N, Koch C. Information integration without awareness. Trends Cogn Sci. 2014 Sep;18(9):488-496. https://pdfs.semanticscholar.org/b2bc/e89431008d8420539bb84fbcff78643b2c16.pdf
- Kaas JH. The evolution of neocortex in primates. Prog Brain Res. 2012;195:91–102. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3787901/
- Herculano-Houzel S. Coordinated scaling of cortical and cerebellar numbers of neurons. Front Neuroanat. 2010;4:12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2839851/
- Hofman MA. Evolution of the human brain: when bigger is better. Front Neuroanat. 2014;8:15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3973910/#B110
- Lent R, Azevedo FA, Andrade-Moraes CH, Pinto AV. How many neurons do you have? Some dogmas of quantitative neuroscience under revision. Eur J Neurosci. 2012 Jan;35(1):1-9.
- Loorits K. Structural qualia: A solution to the hard problem of consciousness. Front Psychol. 2014;5:237. DOI: 10.3389/fpsyg.2014.00237 PMCID: PMC3957492. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3957492/
- Van Gulick R. Consciousness. Zalta EN, editor. The Stanford Encyclopedia of Philosophy (Summer 2017 Edition). Retrieved 2017 Sep 8 from https://plato.stanford.edu/archives/sum2017/entries/consciousness
- Oizumi M, Albantakis L, Tononi G. From the phenomenology to the mechanisms of consciousness: Integrated Information Theory 3.0. PLoS Comput Biol. 2014 May;10(5):e1003588. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4014402/pdf/pcbi.1003588.pdf
- Tononi G. Integrated information theory of consciousness: An updated account. Arch Ital Biol. 2012 Jun-Sep;150(2-3):56-90. http://www.architalbiol.org/aib/article/download/15056/23165867
- Tononi G, Koch C. Consciousness: Here, there and everywhere? Philos Trans R Soc Lond B Biol Sci. 2015 May;370(1668):20140167. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387509/
- Chalmers DJ. Absent Qualia, Fading Qualia, Dancing Qualia. In Metzinger T, editor. Conscious Experience. Ferdinand Schoningh. pp. 309–328 (1995). Retrieved 2017 Apr 06 from http://consc.net/papers/qualia.html