Visual Functions of the Thalamus

Abstract

The thalamus is the heavily interconnected partner of the neocortex. All areas of the neocortex receive afferent input from and send efferent projections to specific thalamic nuclei. Through these connections, the thalamus serves to provide the cortex with sensory input, and to facilitate interareal cortical communication and motor and cognitive functions. In the visual system, the lateral geniculate nucleus (LGN) of the dorsal thalamus is the gateway through which visual information reaches the cerebral cortex. Visual processing in the LGN includes spatial and temporal influences on visual signals that serve to adjust response gain, transform the temporal structure of retinal activity patterns, and increase the signal-to-noise ratio of the retinal signal while preserving its basic content. This review examines recent advances in our understanding of LGN function and circuit organization and places these findings in a historical context.

Keywords: LGN; cat; mouse; primate; retina; vision.

Figure 1

Nissl-stained sections of the lateral geniculate nucleus (LGN) from nine different species: (top row) human, chimpanzee, rhesus macaque; (middle row) cebus monkey, galago, tree shrew; (bottom row) domestic cat, flying fox, rat. Adapted with permission from Usrey (2002a).