GP neurons receive excitation from the subthalamic nucleus (STN) and inhibition from the striatum and from other GP neurons ( Falls et al., 1983 Kita and Kitai, 1994 Smith et al., 1998 Sadek et al., 2007). The globus pallidus (GP in rodents, GPe in primates) is a tonically active, inhibitory nucleus in the basal ganglia indirect pathway.
The dendritic NaF channel expression pattern may therefore be a critical determinant of convergence for both the striatopallidal and subthalamopallidal projections, while also dictating which spatiotemporal input patterns are most effective at driving GP neuron output. Higher dendritic NaF channel expression also made the neurons more resistant to tonic inhibition and highly sensitive to clustered synchronous excitation. The models were all similar in their basic electrophysiological features however, higher expression levels of dendritic NaF channels increased the relative effectiveness of distal inputs for both excitatory and inhibitory synapses, broadening the effective extent of the dendritic tree. We built a series of nine GP neuron models that differed only in their dendritic NaF channel expression level to assess the functional impact of this parameter. Antibody labeling has demonstrated the presence of NaF channel proteins in GP dendrites, but the quantitative expression density of the channels remains unknown. Dendritic expression of fast voltage-dependent Na + channels (NaF channels) can enhance the importance of distal excitatory synapses by allowing for dendritic spike initiation and by subthreshold boosting of EPSPs. Because of the length and fine diameter of GP dendrites, however, it is unclear how much influence distal synapses have on spiking activity. They have long dendrites that can extend through one-half the diameter of the GP in rats, potentially enabling convergence and interaction between segregated basal ganglia circuits. The globus pallidus (GP) predominantly contains GABAergic projection neurons that occupy a central position in the indirect pathway of the basal ganglia.
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