Abstract

1.1 Bilateral damage to the thalamus abolishes waking consciousness. The critical site of this damage is believed to be a relatively small cluster of neurons, about the size of a pencil eraser on either side of the brain's midline, called the Intra-Laminar Nuclei (ILN) because they are located inside the white layers (laminae) that divide the two thalami into their major groupings of nuclei. The fact that bilateral damage to the ILNs abolishes consciousness is very unusual. There is no other site in the brain that has this property, except the reticular formation in the brain stem. In contrast, huge chunks of cortex can be damaged without abolishing the STATE of consciousness. (Cortical damage does change the CONTENTS of consciousness, of course).