A note on the projection from the rostral thalamus to the visual hyperstriatum of the chicken (Gallus gallus).

The rostral thalamo-hyperstriatal projection in young chicks was examined following large injections of wheat germ agglutin labelled with horseradish peroxidase (HRP-WGA) into the hyperstriatum. Retrograde labelling of thalamic neurons was present in the dorsolateral thalamus, rostrolateral part (DLAlr) and dorsolateral thalamus, lateral part (DLL). There was no evidence of a contralateral projection from the lateral anterior thalamic nucleus (LA) to the posterior aspect of the visual hyperstriatum as reported recently by Boxer and Stanford (1985). Furthermore, a comparison of labelled neurons in the contralateral rostral thalamus following injections into either the left or right hyperstriatum revealed no difference in the number of neurons. The study could therefore not confirm the presence of an asymmetrical LA-hyperstriatal projection, as reported by the above authors.