On the projections from the neostriatum to the cerebral cortex: the "displaced" neurons

The entire dorsal and lateral cortex of one cerebral hemisphere of rats was infiltrated with different fluorescent tracers and the neostriatum was examined for labelled perikarya. In spite of the extensive infiltration of the cortex, such neurons were seen only sporadically in the ipsilateral neostriatum and almost only in the vicinity of the globus pallidus and the subcortical white matter. The size and shape of these neurons, and particularly their proximity to some cell groups which surround the neostriatum and project to the cerebral cortex, suggest that these neurons belong to the neighbouring structures such as the magnocellular nuclei of the basal forebrain, the claustrum and the VIb cortical layer.