Superficial and Deep Thalamo-Cortical Projections from the Oral Part of RHE Ventral Lateral Thalamic Nucleus (VLo) Receiving Inputs to the Internal Pallidal Segment (GPi) and Cerebellar Dentate Nucleus in the Macaque Monkey

Superficial thalamo-cortical (T-C) responses were recorded in the lateral motor area and dorsal premotor area (PMd) following stimulation of the cerebellar dentate nucleus in monkeys (Sasaki, 1979). These responses were also recorded in the motor area following pallidal stimulation (Nambu et al., 1988; 1991). An anatomical study was also carried out on the T-C projections from the motor thalamic subdivisions in monkeys using autoradiography (Nakano et al., 1992). The latter fmdings demonstrated that the basal ganglia territories of the motor thalamic subdivisions give rise to superficial T-C projections, whereas the cerebellar territories give rise only to deep T-C projections. Recent studies, using modem axonal tracing techniques, have reported a possible overlap of basal ganglia and cerebellar inputs in the thalamic subdivisions (Rouiller et al., 1994; Sakai et al., 1996). We have reported that the lateral parts of the nucleus ventralis lateralis pars oralis (VLo) receive cerebellar afferents from the ventral part of the dentate nucleus (Nakano et al., 1996).