The Design of the Neuronal Correlate of Consciousness (NCC): Theory of Consciousness

The NCC

The design of a NCC is based on the assumption that such a mechanism exists in humans and animals. In 1940, The gestalt psychologist Wolfgang Kohler wrote: “It is now almost generally acknowledged that psychological facts have “correlates” in the biological realm. These correlates, the so called psych-physical processes, are events in the central nervous system” (Kohler,1940)
Francis Crick and Christof Koch argued that neurobiology can explain consciousness (Crick and Koch, 1992). Without defining “consciousness”, they presented a rationale that “consciousness was to be found in the study of the analytic processing of the visual system”. At the turn of the century, they wrote that “The most puzzling aspect of vision and visual perception is that it gives rise to conscious “seeing” and that “consciousness”, now viewed as a subjective experience or a sentience sensation, was to be found in a Neuronal Correlate of Consciousness (NCC). They write: “To characterize the NCC we have to contrast neural activity that directly gives rise to conscious sensation, thought and action with neuronal activity that is associated with unconscious stereotyped, and on-line visuomotor behavior. Where is the difference between these forms?” (Crick and Koch, 2004, 2000).
The question begs the answer. The NCC must be “that neural activity that directly gives rise to conscious sensations”. Neuronal activity requires a correlate of consciousness since neuronal activity per se, will always give rise to more neuronal activity, not to a conscious sensation.
In this paper, it is proposed (as a working hypothesis) that a neuronal circuit (and the neuronal activity of that circuit), which may be defined as a NCC circuit, is always correlated with conscious sensations. That is, consciousness itself, is an attribute of the NCC. The NCC itself is a neuronal circuit in the brain, a mechanism that may be called a Consciousness Mechanism (CM).
The design of the NCC is based on reverse engineering the assumed functional utility of the modalities of the sensors of the various biological sensory systems. The functional utility of consciousness and the NCC is assumed to result from a Darwinian adaptation that evolved in all animals with a well developed CNS. The functional utility of various modalities is assumed to support the adaptation and survival of the organism in its environmental niche.
“Neuronal activity that directly gives rise to conscious sensation” has been discovered in the biological sensory system. Therefore the starting point for a design of a NCC circuit should be the modalities of the various sensors of the biological sensory systems. In medical text-books (Guyton, 1991) and most neuroscience text-books (Kandel et al 1991; Gazzaniga et al 2002; Bear et al, 2001), the modalities of sensors are defined in terms of the conscious sensation that they evoke. The law of specific nerve energy is often referred to explain the unique conscious sensation that each modality generates (Guyton, 1991; Haines 2002). The law of specific nerve energy ensures that each type of sensor responds specifically to the appropriate form of stimulus so as to give rise to a specific sensation. Furthermore, modality specificity is maintained in the central connections of sensory axons, so stimulus modality is represented by receptors, afferent axons and central pathway that it activates (Haines, 2002).
The sensory system selected for the preliminary design of the NCC was the somatosensory system rather than the visual system, as suggested by Crick and Koch (1992). The reasons are: a) The somatic body sensors evolved earlier and the gross features of the design are shared with a large number of vertebrates and invertebrate, b) The modalities of the somatic sensors are very well defined compared to the modalities of the retinal receptors, and c) Reverse engineering the operation of somatic sensors is a relatively less complex task than reverse engineering the operation of the binocular visual system.

Reverse Engineering the NCC

Steven Pinker, in his Book, How the Mind Works (1997), ponders over the mysteries of a beautifully designed complex mechanical mechanism. In a flash of light, the mysteries of the mechanism are solved with a giant leap of understanding when he discovers the utility of the mechanism; an “olive pitter”, beautifully designed to remove the pit from the olive. So with the utility of the attribute of consciousness; and in this publication we shall often refer to the NCC as a Consciousness Mechanism (CM). The usual engineering approach for the bioelectric design of a mechanism that has never before been designed into a machine, is reverse engineering the functional utility of the mechanism. However, a operational definition of that mechanism was not available, so that the overriding principle used throughout the study was Darwinian survival and reverse engineering (Dennett,1995) the evolutionary adaptation (Williams, 1966; Grafen, 1997) and known connectivity of the human and animal body and brain. The functional utility of the CM was assumed to be supportive of Darwin’s law of natural selection and the survival of the fittest.
In the following sections a building path is specified for a reverse engineered NCC circuit. The functional characteristics of the reverse engineered NCC are designed to be similar to the functional characteristics of the biological NCC. The proposed design adheres to Daniel Dennett’s reverse engineering requirement “No sound functional analysis is complete until it has confirmed that a building path has been specified” (Dennett, 1997)

The Known Functional Characteristics of Consciousness

The cognitive scientist, Steven Pinker (1997), refers to Ray Jackendoff (1987) and Ned Block (1995) in discussing the 4 characteristics of “consciousness.” The functional characteristics of the mind or brain include 1. Self Knowledge. 2. The mind builds an internal model of the world that includes the “self”. 3. Access to information or “access consciousness”: Not all the functional information of the brain and body is accessible to the mind. F. Crick and C. Koch (1995) determined a set of criteria relating to what one should look for in “access consciousness”. 4. Sentience or “qualia”: A subjective experience, feeling or sensation.
The design of the fourth quality of consciousness was an elusive goal. On the one hand a large number of functions of the body and brain are described in terms of the CM (i.e. sensory modalities are described in terms of the subjective experiences they evoke. For example the sentience associated with perception and emotion). On the other hand, a “subjective experience” is an attribute (such as experiencing a “force” or the passage of “time”), that can only be a correlate associated with the operation of a material machine or circuit (a spring or clock).
The fourth quality, the sentience characteristic of consciousness, related to “a subjective experience, requires the assumption of a working hypothesis. The working hypothesis proposed in this analysis is that the “subjective experience” or sentience, the fourth characteristic of consciousness, is an attribute-byproduct present in every organism or machine that is designed to adhere to the first 3 characteristics enumerated above.
Proof of the hypothesis, and the conversion of the hypothesis into a theory will be obtained by reverse engineering the connectivity of the first 3 functional characteristics of consciousness, generalizing, observing and testing the “subjective experience” predictions of the designed connectivity, and by measuring and testing the extent to which the assumed biological functional utility of the mechanism is also shared by a reverse engineered machine.
The main content of this publication consists of the reverse engineered design of the connectivity, the neuronal pathways of the body and brain, that form a NCC circuit that adheres to the first 3 functional characteristics of consciousness. That NCC circuit, called a Relational Robotic Controller (RRC) circuit, may be viewed as a neural network based robotic controller circuit that emulates some of the biological functions of the animal brain1.

The Neuroscience Problems Associated with the Design of the NCC.

The design of the neural network, the RRC “brain-like” controller, must satisfy the first 3 functional characteristics of consciousness and must also adheres to Dennett’s reverse engineering requirement “No sound functional analysis is complete until it has confirmed that a building path has been specified” (Dennett, 1997). The building path selected to adhere to the Dennett’s requirement is to design and build a non-biological RRC brain like controller that has the first 3 functional characteristics enumerated above. That is, the RRC controller must control a reverse engineered mechanical robot that emulates the biological somatic motor system and sensors.
The requirements placed on the design of the RRC leads to reverse engineering 4 neuroscience functional characteristics. These functional characteristic translate into 4 neuroscience problems:

Problem 1

How to build a neural network, that adheres to the second “consciousness” constraint: The mind builds an internal model of the world, a “world-space” that includes the “self” in the center.
The selected approach was to design an “homunculus” in the brain that is defined by the somatic body sensors, and to define the world space around the homunculus by the positions occupied by flailing limbs.

Problem 2

How to give the RRC “world-space” circuit “self”-knowledge.
The selected approach was to assume that “self” knowledge would be the measured location data related to the robotic “self”. That is, the robot would be required to learn the location of each of its surface parts with respect to and related to the other surface parts. This knowledge was to be gained by learning how to move a robotic limb towards any and every other part of the robotic body. In other words the robot would have the capability to perform a itch-scratch response, by moving a limb through a goal directed, obstacle avoiding trajectory aimed at a “itch” point on the robotic body.
Obstacle avoidance along the trajectory generates an additional neuro-scientific constraint on the RCS. That is, the trajectory of motion must be pre-planned with the option available for re-planning the pre-planned trajectory when an obstacle is detected along the path of the pre-planned trajectory2 (Kandel 1991, Gazzaniga 1998).

Problem 3

How to design the RRC so that the trajectory of motion is pre-planned and goal directed with the option of re-planning a pre-planned trajectory.
The selected approach was to decompose the trajectory of motion into small transitions to adjacent nodes wherein during each frame period the total goal directed trajectory is determined by the RRC as a sequence of small transitions, but only the first small transition is activated by the controller. That is the maximum speed of operation of the robot is one transition per frame period. The design of the RRC was constrained to adhere to the cognitive science constraint for goal directed and volitional action. That is, the motion must be pre-planned and goal directed, with the volitional constraint option available for re-planning a pre-planned goal directed trajectory when obstacles are detected at mid-points along the trajectory.

Problem 4

How to train/program the RRC world-map to perform “location”, “ relational”, “itch-scratch” type actions. The selected approach was to utilize state of the art techniques for training/programming a neural network.
Conclusion
The working hypothesis may be invoked when the first 3 functional characteristics of consciousness have been successfully designed into the RRC circuit. The working hypothesis correlates a subjective experience, the sensation of tactile consciousness to the function of the RRC (NCC)-circuit. An operational definition of tactile consciousness, and a tactile theory of consciousness may then be submitted. A generalized theory of consciousness follows by the application of the tactile theory to other sensors with different sensory modalities

The Modality of the Consciousness Mechanism

The previous sections presented a well defined “building path” for a RRC circuit that satisfies the first three functional characteristics of consciousness; the formation of a world map in the brain, self-knowledge, and access to information.

The world map in the brain: The RRC satisfies the fundamental cognitive science constraint that the brain generally forms a model of the external world and places the “self” at its center, (Pinker, 1997). The peripheral tactile sensors that define the homunculus simulate the “self” in the brain, and the flailing limb tactile sensors are used to simulate the external world.

Self-knowledge:

A RRC controlled robot may therefore be trained with a primary task of locating itself in the external world. The primary task consists of a set of navigational tasks that teach the robot the location of any peripheral part of the robot with respect to any other part. For example, a robot equipped with thousands of pressure transducers uniformly distributed on the peripheral body of the robot. Self-knowledge is gained by the RRC robot when it is trained and “learns” to navigate a robotic finger, located at the end of a robotic arm, so as to “touch” any one of the pressure transducers distributed on the periphery. This trained nodal map is referred to as the “self location and identification”, or the “self”-nodal map of the robot. A robot that is designed to “know itself” is programmed to perform body-part-location tasks of all moveable body parts relative to all other body parts. All other tasks are performed relative to the primary “self” identification task.

Access to information, “access consciousness”, and the modality of the sensors: The RRC, thus far, has limited access to information that is related to self-knowledge within a world map in the brain. This knowledge arises from the pressure transducers (mechanoreceptors on the skin surface) and angle measuring transducers (proprioceptors embedded in muscles and joints). In biological systems, the receptor type and the signal emanating from it is classified in terms of its modality. In most medical and neuroscience text books the modality of a receptor is defined in terms of the subjective experience it evokes (Guyton 1991, Kandel 1991, Haines 2002, Bear et al 2001). For example, the class of skin surface mechanoreceptors that give rise to tactile sensations, sub-serve the “touch” sensor modality. Different mechanoreceptors within the “touch” modality respond best to stimuli that give rise to the sensation “tickle, itch, flutter, or vibration. The sensors and the associated sensations are classified by Haines (2002) as sub-modality specialization within a modality. Other modalities associated with specific receptors and defined by the subjective experience they evoke are fast pain and slow pain receptors, heat and cold receptors, and light and sound receptors that sub-serve the visual and auditory modality. Haines refers to the “law of specific nerve energy” to describe the specificity of receptor transduction (acting as transducers) that ensures they respond best to the appropriate form of stimulus for the sensory system they serve. This modality specificity is maintained in the central connections of sensory axons, so stimulus modality is represented by the receptors, afferent axons and central pathway that it activates (Haines et al 2002, p.47). Furthermore, the central pathways or connectivity associated with the pressure and angle measuring modalities are completely designed in the RRC controller, and may be indicative of the neuronal pathways in the brain.
The RRC circuit is therefore the Neuronal Correlate of Consciousness (NCC). It is the Consciousness Mechanism (CM) by which subjective experience associated with each modality is perceived by the “self location and identification” circuit.

The working hypothesis becomes a postulate: There is general concurrence (Guyton 1991, Kandel et al 1991, Gazzaniga et al 2002, Haines 2002, Bear et al 2001, Purvis et al 1997) that the subjective experience, the 4th characteristic of consciousness, is associated with the modality of the sensor, wherein different modalities give rise to different subjective experiences. Therefore the 4th characteristic of consciousness, the subjective experience or sentience that was presented earlier as a working hypothesis, may now be stated as a postulate.

Postulate

The ’subjective experience” or sentience, the 4th characteristic of consciousness, is an attribute or byproduct present in every organism or machine that is designed to adhere to the first 3 functional characteristics of the NCC. This Postulate is the basis for a theory of consciousness.
Theory of Consciousness: The subjective experience is an attribute of the modality of sensory receptors that are connected to the “self identification and location” circuit (NCC) in a manner such that the sensory signal contributes to “self” knowledge within the world map in the brain.

Definition of Perception:

Whenever a sensory receptor signal gives rise to a “conscious” subjective experience then it is said to be “perceived” by the organism. It is important to distinguish between perception and identification or recognition. The connectivity of the reverse engineered NCC has been completely determined so as to give rise to conscious perception. In order to achieve recognition or identification of the perception additional circuitry is required (Rosen 2003e)8. During the past half century, since Hubel and Weisel (1962) discovered that different regions of the visual cortex responded to different parts of the visual image (boundaries shapes colors), it was assumed (since the mechanism for perception was not yet discovered) that the brain was functioning to perform recognition or identification of boundaries, shapes or colors. With this presumption, since recognition or identification must be performed on the total image, a large fraction of the research of the past 40 years has been devoted to finding anatomical brain locations that reconstruct the image from its various parts (boundaries shapes colors), (see for example S Grossberg (2004); S. Zeki (1993)). According to the theory of consciousness, such reconstruction is un-necessary for the perception of an image (Rosen 2003b). Reconstruction is performed by the CM (the NCC), wherein the different modalities of vision (receptive fields in the retina that specialize in boundary discrimination, shape discrimination, and color discrimination in the light and dark) are combined to form a conscious perception of the total image (Rosen 2003b). Much of the functional and anatomical research aimed at the study of central pathways that are active in the operation of the NCC should be guided by the observation that modality specificity is maintained in the central connections of sensory axons, so that stimulus modality is represented by receptors, afferent neurons and central pathways that it activates (Haines et al 2002, p47). Every sensory input signal that is connected to the RRC-“self” circuit is perceived by the organism. The subjective characteristic of the perception is determined by the modality of the sensory receptor.

Self Consciousness:The modalities of mechanoreceptors, proprioceptors, and vestibular sensors.

The somatic sensors respond to at least 4 kinds of stimuli; touch, temperature, pain and body position. A single sensory receptor can encode stimulus features such as intensity, duration, position, and sometimes direction (Bears et al 2001, p.398). Sensory receptors produce local graded potentials whose amplitude parallels the amplitude of the stimuli. The graded potentials are produced by modulating the “open times” and hence the permeability of ion channels, shifting the membrane towards or away from the equilibrium potentials for the ions they conduct. The general organization of somatic sensation is given in most medical physiological and neural science textbooks (for example Guyton 1991 chapter 47, and Haines 2002 Chapter 17). The receptor type (modality), the associated fiber types, the signal transmission characteristics and the type of sensation evoked by each receptor type is also presented those textbooks.

Self Consciousness: Mechanoreceptors and Nociceptors.

Skin performs an essential protective function and prevents the evaporation of body fluids into the dry environment. It is the largest sensory organ we have. Mechanoreceptors are embedded in the dermis under glabrous epidermal layers and hairy epidermal layers. Skin can be vibrated, pressed, pricked, and stroked, and its hairs can be bent and pulled. Thus we may define the “touch-pressure, tap, flutter, vibration“ sentient as a subjective experience mediated by cutaneous (skin) mechanoreceptor modalities. The “intensity” of the experience is determined by the intensity or value code that is present in the signal. The distribution of mechanoreceptors may be determined by a study of 2 point discrimination on the body surface. Finger tips receptors are 2.5 mm apart, lips 5 mm, Big toe 1 centimeter, forearm 3.5 centimeter, back 4.2 centimeter, and calf 4.6 centimeter (Bear et al 2001, p. 402).
The sensation of pain is mediated by nociceptors embedded in the skin surface and throughout the internal organs. Visceral nociceptors mediate visceral pain (heart, lung irritants, gastrointestinal tract pain, urological tract pain etc.).

Self Consciousness: Proprioceptors and the vestibular apparatus.

Proprioceptors and the vestibular apparatus mediate the experience of “self” consciousness. The experience of “self’ consciousness (Joint movement, muscle tension, length and rate of change, length and velocity) is a subjective experience mediated by muscle and joint proprioceptors modalities. The intensity of the experience is determined by the intensity or value code present in the signal.
Limb proprioception is mediated primarily by muscle afferent fibers (Kandel 1991, p. 346). There are 2 sub-modalities of limb proprioception: the sense of stationary position of the limb (limb position sense) and the sense of limb movement (kinesthesia). Proprioceptive sensations of the limb generally occur as a consequence of voluntary (or reflexive) movement. In discussing proprioceptive sensations Kandel (p. 337) shows that the CM is utilized to determine knee position. For example it was shown that limb position and kinesthesia are well developed in the absence of voluntary muscle contraction. At rest, the angle of the knee can be evaluated to within 0.5 degrees. Thus, perception of limb position and movement is mediated by three main types pf peripheral receptors that signal the stationary position of the limb and the speed and direction of limb movement: 1. Mechanoreceptors located in joint capsules, 2. Muscle spindle receptors, mechanoreceptors in muscles that are specialized to transduce stretch of the muscle and 3. Cutaneous (skin) mechanoreceptors.
The experience of balance or dizziness sensation is a subjective experience mediated by the vestibular apparatus (the organ that detects the sensation of equilibrium) in the inner ear. The orientation sensation and magnitude of the experience is determined by the value codes present in the various signals generated by the apparatus.
Different receptors respond to the different mechanical energies (sub-modality). The different receptors have different axonal pathways, (by primary afferent axons via the spinal chord and the trigeminal touch pathways for the face mouth and tongue) and stimulate different regions of the brain.

Conclusion:

The Utility of the CM

The CM, also known as the NCC, is an evolutionary adaptation that has never before been designed into a machine. Its functional utility is that it enhances the Darwinian survival of the organism. The CM is the basis for perception of the external world, self awareness and sensory-motor control, perception and feedback (self awareness) of the internal reaction of the body to external forces, and emotional drives and the motivational system in the brain.

Perception of the external world: A recording monitor in the brain.

The configured input circuit, the tactile self-circuit defined by the modalities of the mechanoreceptors distributed on the skin surface of the body, form a recording monitor in the brain. During the life of the organism, whenever a modality is activated the CM is also activated. The constant monitoring of the subjective experience of touch-feeling or pain-pressure enhances Darwinian survival by supporting the Darwinian search engine that gives the organism knowledge of environmental contingencies; danger, food and shelter or mating opportunities4. The CM and the Darwinian search engine that is used to search the environment for environmental contingencies that impact the survival of the organism, also gives rise to the subjective experience of “seeing”, “hearing”, “smelling”, and “tasting”.

Motor control

Self awareness and self knowledge of the “measure” of the near space (with the self in the center) coupled with self awareness of the internal reactions of the body to external stimuli, are powerful sensory-motor control tools for all locomotive actions performed by all body parts. The CM mediated by the proprioceptors and vestibular system and coupled with location “self” knowledge, operates as a feedback loop that facilitates learning precision control of body motion in an external environment defined by the world map in the brain. “Perception” coupled with “self awareness” generates a powerful tool for designing and building a volitional humanoid robotic system (Rosen 2003c). In most modern publications relating to sensory-motor control of the somatic motor system, the power of the CM is rarely taken into consideration and the connectivity associated with it, in the form of a neural representation for sensory-motor control, is never taken into consideration (See for example Guenther et al, 2001)5.

The CM and Emotions

Emotions are subjective experiences that may also be correlated with the CM. In 1884, in an article titled “what s an emotion” William James defined the Neuronal Correlate of Emotion (NCE) as that which “upsets” the equilibrium of an autonomic organic system (James, 1984). Rosen et al (Rosen, 2003e) defined an emotion as the modality of internal sensors that detect the change in state of an autonomic organic system (often controlled by the endocrine system). The subjective experience of emotions is a CM that may be used to design a motivational system in the brain. The emotional CM was used by Rosen et al (Rosen 2003e) to design a control system for the involuntary autonomic nervous system and connective model of an autonomous Darwinian TSM that emulates the motivational system in the brain. With a CM for perception, a CM for voluntary control and feed back of the somatic motor system, an emotional CM for the control of the autonomic organic system, and a CM-derived motivational system in the brain, it may be possible to close the functional loop between the voluntary somatic motor system, the involuntary autonomic system, and the motivational system in the brain and thereby present an analytic solution to the mind-body problem (Rosen 2003e).
The CM and Neurological and Medical studies
The CM may facilitate neurological studies of the structure and connectivity of portions of the brain associated with locomotion and perception. With knowledge of the connectivity of the CM and a model of the operation of a reverse engineered robotic controller, it may be possible to generate additional constraints relating to the neuronal pathways and functional operation of the human and animal brain7.
The CM is closely related to the psychological-medical well being of animals and humans (The subjective experience of “how do you feel”). The medical field makes extensive use of the CM often without recognizing its mechanistic nature. With knowledge of the operation and connectivity (neuronal pathways) of the CM it may be possible to enhance the efficacy of the art of sensory-healing, health enhancement, and the role of acupuncture, meditation, relaxation, stretching, exercise, massage, and hot and cold compresses.

The CM and illusions

Consciousness is a subjective experience that may be classified as an illusion. The CM has a mechanistic connectivity associated with it that builds (in the brain) an illusional world with the “self” in the center. When operating in a normal manner, this illusional world is a close approximation to the real world and the real “self” operating in the world. Unfortunately, no matter how close the illusional world is to the real world, the real self is never at the center of the universe. The real “self” occupies an infinitesimal region of the universe that is shared with billions of other creatures. This illusion does not reflect reality, but it is an excellent Darwinian survival mechanism. Abnormal functions of the CM (subjective experiences) give rise to illusions and fantasies that are in the field of study of abnormal psychology and psychiatry. The major source of conflict is the role of the “self” in the real world versus the role of the “self” in the illusional world-space within the brain. The connectivity of the CM raises questions relating to normal and abnormal psychology. For example, in the arena of tactile connectivity, what is the subjective experience associated with the activation of “un-occupied” neurons in the near (world) space (neurons that are normally activated only when occupied by flailing limbs)? The visual system, in particular is subject to illusional perceptions that may not correspond to the real world (Rosen 2003b). The application of the CM to auditory (musical and verbal) “hearing”, and the “emotional” hedonic pain-pleasure sensations that are experienced by all mammals, is described by Rosen et al ( 2003f and 2003e).

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