The physiological role of dopaminergic modulation on striatopallidal synaptic transmission

Abstract

Basal ganglia are a group of subcortical nuclei, composed of striatum, globus pallidus, subthalamic nucleus, and substantia nigra. The basal ganglia integrate diverse information that is widely distributed over the cortex and filter out the strategy of willed movement. To modulate this system, the neurotransmitter dopamine from midbrain dopamine neurons is essential. Although the roles of dopamine on the striatum have been intensively studied so far, the physiological functions of dopamine on striatopallidal synapses remain unclear due to relatively sparse dopaminergic innervation on globus pallidus. Here, we utilized enhanced confocal imaging and synapse analysis to examine the functional relationship between dopaminergic and striatopallidal synapses. We also used electrophysiology combined with optogenetics to selectively stimulate striatopallidal synapses and dissect out dopaminergic modulation of striatopallidal synaptic transmission. We found that there is a marked regional heterogeneity in the dopaminergic innervation of globus pallidus. Furthermore, dopamine differentially regulated striatopallidal synaptic transmission in a region-specific manner. Since striatopallidal synapses function as a critical gateway of indirect pathway in the basal ganglia circuitry, our findings will provide new insights into the overlooked role of dopaminergic modulation on striatopallidal synapses and globus pallidus.