Connections of the thalamic reticular nucleus with the contralateral thalamus in the rat.

The occurrence of thalamic projections to the contralateral side of the thalamus, and the origin of these projections from the thalamic reticular nucleus, were demonstrated with fluorescent retrograde tracing. After a relatively large tracer injection in the anterior third of the thalamus (involving the reticular, anterior, intralaminar and ventrolateral nuclei), labeled cells were detected in the rostral portion of the contralateral reticular nucleus. The location within the reticular nucleus of the neurons retrogradely labeled in the contralateral thalamus was confirmed by means of the combination of tracing with immunocytochemistry, using antibodies against the calcium binding protein parvalbumin.