Claustrum

The claustrum (Latin, meaning "to close" or "to shut") is a thin sheet of neurons and supporting glial cells in the brain, that connects to the cerebral cortex and subcortical regions including the amygdala, hippocampus and thalamus. It is located between the insular cortex laterally and the putamen medially, encased by the extreme and external capsules respectively. Blood to the claustrum is supplied by the middle cerebral artery. It is considered to be the most densely connected structure in the brain, and thus hypothesized to allow for the integration of various cortical inputs such as vision, sound and touch, into one experience. Other hypotheses suggest that the claustrum plays a role in salience processing, to direct attention towards the most behaviorally relevant stimuli amongst the background noise. The claustrum is difficult to study given the limited number of individuals with claustral lesions and the poor resolution of neuroimaging.

The claustrum is made up of various cell types differing in size, shape and neurochemical composition. Five cell types exist, and a majority of these cells resemble pyramidal neurons found in the cortex. Within the claustrum, there is no laminar organization of cell types as in the cortical layers, and the cell bodies can be a pyramidal, fusiform or circular. The principal cell type found in the claustrum is the Golgi type I neuron, which is a large cell with dendrites covered in spines. Through interhemispheric connections, the claustrum is believed to play a role in synchronizing activity in widely separated, but functionally related, parts of the brain such as between frontal eye fields and the visual cortex. As such, the claustrum is thought to play a role in combining different information modalities, potentially to support consciousness itself. Another proposed function of the claustrum is to differentiate between relevant and irrelevant information so that the latter can be ignored.

Cortical components of consciousness include the fronto-parietal cortex, cingulate and precuneus. Due to the claustrum's widespread connectivity to these areas, it is suggested that it may play a role in both attention and consciousness. The neural networks that mediate sustained attention and consciousness send inputs to the claustrum, and one case report in humans suggests that electrical stimulation near the claustrum reversibly disrupted the patient's conscious state. Provided by Wikipedia