The ventral striatopallidothalamic projection: I. The striatopallidal link originating in the striatal parts of the olfactory tubercle.

The projections from the striatal part of the olfactory tubercle were examined in rats, both with the aid of experimental silver impregnation methods following superficial laminar heat lesions of the tubercle and by the use of anterograde transport of Phaseolus vulgaris-leucoagglutinin (PHA-L) following injections of the lectin in the dense cell layer of the tubercle. Retrograde transport of fluorescent substances following injections of the tracer in the multiform layer of the tubercle were used to corroborate the results obtained by the anterograde transport and degeneration methods. The main and apparently only significant termination from the striatal cells in the olfactory tubercle is located immediately deep to the dense cell layer in areas that could be identified as part of the ventral pallidum on the basis of either the Nissl method or glutamate decarboxylase immunocytochemistry. Whereas a mediolateral topography is generally maintained by the ventral striatopallidal pathway originating in the dense cell layer, there is a considerable spread of the projection in the rostrocaudal direction. The dense projection field of the olfactory tubercle component of the ventral striatopallidal pathway permeates the ventrolateral part of the ventral pallidum, thereby complementing the termination of the accumbens projection to the more mediodorsal parts of the ventral pallidum.