The lateral geniculate nucleus does not project to area TE in infant or adult macaques

Abstract

We sought to determine if there are any direct projections from the dorsal lateral geniculate nucleus (dLGN) to visual cortical area TE in either adult or infant primates. To do so, we examined labelling in the thalamus of eight macaque monkeys which received injections of the retrograde tracer cholera toxin B-subunit within TE. Four of these cases were infants in which the injections revealed transient patterns of inputs to TE from various other brain regions. Although each monkey showed extensive label in the pulvinar nucleus and other subcortical structures, none showed unambiguous labelling in the dLGN. The absence of direct connections between the dLGN and area TE indicates that rudimentary color and form processing capacities in the absence of striate cortex must utilize other pathways even when damage to striate cortex takes place early in life.