Abstract
The thalamic lateral posterior nucleus (LP) of the hooded rat is regarded as a relay nucleus for the transmission of information from visuomotor-related structures such as the superior colliculus, pedunculopontine tegmental nucleus (PPT) and substantia nigra, pars reticulata, to visual cortical areas as well as the striatum. The aim of the present study was to examine the relationships of the thalamo-striatal projection neurons with the LP afferent fibers derived from the PPT, using injections of the anterograde tracer biotinylated dextran amine (BDA) and the retrograde tracer cholera toxin-B (CTB) into the PPT and the striatum, respectively. Findings showed that the location of terminals derived from PPT and LP neurons projecting to the striatum overlapped considerably in the ventral portion of the LP. Ultrastructural observations within this overlapped LP region showed that BDA-labeled terminals make synaptic contacts with dendrites of CTB-labeled neurons. The present results thus provide morphological support for the contention that information from the PPT neurons is relayed to the striatum through by the LP.
