Loss of consciousness
Loss of consciousness may occur as the result of traumatic brain injury, brain hypoxia (e.g., due to a brain infarction or cardiac arrest), severe poisoning with drugs that depress the activity of the central nervous system (e.g., alcohol and other hypnotic or sedative drugs), severe fatigue, and other causes.
Loss of consciousness occurs in the conditions, such as general (tonic-clonic) epileptic seizures, general anaesthesia, etc.
Cortical network: At present, the best-supported hypotheses about such cases of loss of consciousness (or loss of time resolution) focus on the need for a widespread cortical network, including particularly the frontal, parietal and temporal cortices, and cooperation between the deep layers of the brain, especially the thalamus, and the upper layers, the cortex.
A functioning thalamus is necessary, but not sufficient, for human consciousness; the bilateral surgical removal of the centromedian nucleus of the Intra-laminar nucleus of the Thalamus appears to abolish consciousness, causing coma, persistent vegetative state (PVS).
The studies of blind-sight - vision without awareness after lesions to parts of the visual system such as the primary visual cortex.