Subcortical projections to layer I of the visual cortex, area 17, of the rat

The afferent connections to layer I of the visual cortex, area 17, of the albino rat were studied using the retrograde transport of horseradish peroxidase (HRP). In all animals examined, the majority of labeled cells were observed in the dorsal lateral geniculate nucleus and in the lateral posterior nucleus. In addition, in one-half of the animals examined labeled cells were also present in the posterior complex of the thalamus and in the ventromedial nucleus. Finally, in three cases a few HRP-positive neurons were observed in the locus coeruleus and in the dorsal raphe nucleus.