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Conscience

Category: Cognition• Published on: April 18, 2012• Hits: 13564•

"Consciousness is to the psychologist what gravity is to the physicist: inevitable" (Baars).

Problems of consciousness :

Consciousness [73, 119, 133] is a very difficult subject to study for several reasons [119]. First, there are several definitions of consciousness - the word is used in many different contexts [164] - and second, it involves many brain structures [166] and other higher functions such as memory [73] and language [170].

Another factor adding to the complexity is that consciousness is a purely subjective experience [166] and is therefore only accessible to the person experiencing it; thus, its study must be conducted through human subjects. Animal models contribute very little because it is not yet known with certainty what form of consciousness to attribute to them [41].

General Overview :

Definition :

Consciousness can define several things:

  • The power to focus one's attention;
  • The state of wakefulness ;
  • The faculty of abstraction;
  • The faculty of verbalization - that is, expressing events through words;
  • The ability to develop projects and establish new mental relationships based on past experiences;
  • Self-awareness ;
  • The faculty to establish values...

The unconscious :

To truly understand consciousness, we must also consider the hidden world of the unconscious. Indeed, the brain possesses a multitude of specialized circuits that process approximately 1 billion pieces of data per second regarding various aspects of our environment [142]. Only an infinitely small portion of this data emerges into our consciousness.

Sleep :

Not every state of disrupted consciousness is pathological; unlike comas [57], syncope, or lipothymia, which certainly have pathological origins, sleep constitutes a state of physiological disruption of consciousness that is, moreover, very interesting to study [91, 119].

Classification :

A distinction is made between two forms of consciousness: primary consciousness [170], responsible for vigilance or the state of wakefulness - which is defined primarily by its opposite (loss of consciousness) - and higher-order consciousness [171], such as the definition and distinction of the "self," which is more difficult to study and explain.

The approach to the "self" has historically been the work of philosophers and psychologists; more recently, it has been the subject of several studies that have yet to reach a consensus on their conclusions. It is therefore necessary to clearly define which level of consciousness is being discussed when attempting to associate it with brain structures.

Mechanisms :

Consciousness utilizes short-term memory; processes developing in long-term memory only enter consciousness after passing through short-term memory [133].

Several brain structures that control consciousness in terms of wakefulness are well known. First is the reticular formation [38, 42, 57], the activity level of which influences our state of vigilance, wakefulness, and sleep. Indeed, being awake requires an interaction between the reticular formation and other brain structures, notably the cerebral cortex. For this reason, the ascending pathways of the reticular formation are named the Ascending Reticular Activating System (ARAS) [45].

Next is the thalamus, the "relay station" for all signals originating from the body [38]. Finally, the cerebral cortex [44], whose importance is crucial for all forms of sensory perception and control of voluntary movements [73].

The pons [166], the raphe nuclei, and the locus coeruleus are also structures involved in maintaining primary consciousness [41]. For consciousness to emerge, it appears there must be an exchange or resonance between different regions of the brain. Thanks to functional brain imaging techniques, we can observe the stages that lead to the emergence of a conscious mental image.

Split-brain syndrome :

The most significant experience in the history of the study of consciousness is undoubtedly the study of split-brain syndrome (callosal disconnection syndrome) [133].

In forms of epilepsy resistant to medical treatment that spread to both cerebral hemispheres, a section of the corpus callosum is sometimes performed. Even though this involves cutting approximately 200 million nerve fibers [39, 80], patients notice no significant deficit after the operation. However, elaborate experiments reveal something fascinating: each hemisphere develops its own consciousness, independent of the other hemisphere [73].

If an object is placed in the left hand of the subject while they are blindfolded, they cannot identify the object because the language region - located in the left hemisphere - does not have access to the sensory information, which, in the case of the left hand, reaches the right hemisphere. Nevertheless, the subject is able to draw the object with their left hand [39, 166].