Visual perception in humans and other primates depends on the retino-thalamo-cortical pathway. This pathway begins with retinal ganglion cells, which have axonal terminations in the lateral geniculate nucleus (LGN) of the thalamus. Each ganglion cell axon provides input to one or more LGN relay neurones and, in turn, nearly all the LGN relay neurones project to the primary visual cortex. Thus, ...

The thalamus, once viewed as passively relaying sensory information to the cerebral cortex, is becoming increasingly acknowledged as actively regulating the information transmitted to corti-cal areas. There are a number of reasons for this change. First, evidence suggests that first-order thalamic areas, like the lateral geniculate nucleus, ventral division of the medial geniculate nucleus, and...