Primary consciousness

One prominent theory for the neurophysiological basis of primary consciousness was proposed by Gerald Edelman. This theory of consciousness is premised upon three major assumptions: • The laws of physics apply to consciousness, which rules out concepts such as spirits and a soul and allows for a purely physiological model of consciousness. • Consciousness is an evolved characteristic, which means it is a helpful characteristic from a Darwinian perspective. • There is no such thing as a "qualia-free" observer. Qualia are collections of personal or subjective experiences, feelings, and sensations that inevitably come with human awareness. These scientists also point out that the cortex might not be as important to primary consciousness as some neuroscientists have believed. Evidence of this lies in the fact that studies show that systematically disabling parts of the cortex in animals does not remove consciousness. Another study found that children born without a cortex are conscious. Instead of cortical mechanisms, these scientists emphasize brainstem mechanisms as essential to consciousness. Still, these scientists concede that higher order consciousness does involve the cortex and complex communication between different areas of the brain. ==Neurophysiological basis==

Physiologically, three fundamental facts stand out about primary consciousness: • Waking consciousness is associated with low amplitude, irregular EEG activity in the 20–70 Hz range. • Conversely, unconscious states like deep sleep, coma, general anesthesia, and epileptic states of absence show a predominance of low frequency, high-amplitude and more regular voltages at less than 4Hz. • Consciousness seems to be intrinsically associated with the thalamus and cortex, even if the extent to which this true is argued among scientists. • Damage to the brainstem or thalamus can abolish consciousness, while damage to the sensory cortex appears to delete specific conscious features such as color vision, visual motion, conscious experiences of objects and faces, and the like. • Consciousness is distinctively associated with widespread brain activation related to the conscious content. • Perhaps two dozen experiments show that sensory input supporting consciousness spreads from the sensory cortex to parietal, prefrontal, and medial-temporal cortex, while closely matched input that does not reach consciousness activates mainly local sensory regions. Further, the widespread activity appears to involve more globally coordinated activity. ==Measurement==

To be fully comprehensive, measures of consciousness must not only define and distinguish between conscious and unconscious states, but must also provide a guide by which the conscious level, or extent of consciousness, can be determined. Measures of consciousness are each associated with particular theories. Certain defining theories are included below: Worldly discrimination theory asserts that any mental state that is manifested in behavior is conscious; thus, an organism is consciously aware of something in the world if it can discriminate it with choice behavior. Signal detection theory quantifies discriminability of a stimulus among a set of different stimuli. Integration theories focus on finding a divide between conscious and unconscious processes. According to integration theories, conscious contents are widely available to many cognitive and/or neural processes. These theories are then accompanied with measures of the level of consciousness, which are subdivided into behavioral measures and physiological measures. Abundant evidence indicates that consciously perceived inputs elicit widespread brain activation, as compared with inputs that do not reach consciousness. The dynamic core hypothesis (DCH) proposes that consciousness arises from neural dynamics in the thalamocortical system, as measured by the quantity neural complexity (CN). CN is an information-theoretic measure; the CN value is high if each subset of a neural system can take on many different states, and if these states make a difference to the rest of the system. ==Miscellaneous studies==

In lucid dreams Hobson asserts that the existence of lucid dreaming means that the human brain can simultaneously occupy two states: waking and dreaming. The dreaming portion has experiences and therefore has primary consciousness, while the waking self recognizes the dreaming and can be seen as having a sort of secondary consciousness in the sense that there is an awareness of mental state. Studies have been able to show that lucid dreaming is associated with EEG power and coherence profiles that are significantly different from both non-lucid dreaming and waking. • During generation of moderate thirst by infusion of intravenous hypertonic saline 0.51 M • After wetting of the mouth with water to remove the sensation of dryness • 3, 14, 45, and 60 minutes after drinking water to fully quench thirst The data suggest that the anterior and posterior cingulate cortex as well as the anterior wall of the third ventricle, are major elements of a circuit including thalamic, hippocampal, orbitofrontal, insula, and midbrain sites that are needed for the generation of consciousness of thirst. This mental state corresponds with specific physiological parameters. ==See also==