Cognitive Control of Thalamic Activity

Vanderbilt University Medical Center, Nashville TN

Investigators

Abstract

Underneath the cortex of the mammalian brain lies the thalamus, a structure that has traditionally been considered a 'relay' area for passing practically all sensory information (except olfaction) to the cortex, where sensations are processed and perceived. However, some recent evidence suggests that thalamic functions are dynamically linked to behavioral states such as attention, and that massive connections descend to the thalamus from the cortex, far outnumbering the ascending sensory connections. This project combines visual behavior with electrophysiological recordings from a visual thalamic center called the lateral geniculate nucleus (LGN). The experiments test whether the neuronal activity in LGN is modulated in relation to intended eye movements, and whether neuronal activity in LGN is also modulated by the behavioral demands that may be independent of visual signals themselves. Both these features would lead to a major revision in our understanding of how sensory input reaches the cortex. Results have the potential for a revolutionary change in understanding how crucial the feedback circuits to thalamus are for sensory and cognitive processing, and so will have an impact beyond simply visual neuroscience. This project also provides training opportunities in the sophisticated linking of behavioral and electrophysiological techniques, for students at various levels and including minority students.