Stopping actions by suppressing striatal plateau potentials

Striatal projection neurons (SPNs) in the basal ganglia gradually increase their firing rate during movement initiation. Arkypallidal neurons in globus pallidus briefly increase their firing rate upon a Stop signal, which cues movement cancellation. This increase potentially leads to the suppression of movement-related activity in striatum by inhibiting SPNs. However, this brief inhibition from arkypallidal neurons may be too short to completely prevent the gradual firing rate increase in SPNs. Here, we investigated the impact of the brief inhibition on the gradual increase in a multi-compartmental model of a SPN. We reproduced the movement-related firing pattern in the SPN model neuron by brief clustered excitation added to a baseline, subthreshold excitation. This brief clustered excitation evoked a dendritic plateau potential leading to a long-lasting depolarization at the soma, which enhanced the somatic excitability and evoked spikes upon the baseline excitation that was formerly subthreshold. A brief inhibition, representing arkypallidal stop responses, applied on the dendritic site where the clustered excitation was present, suppressed the somatic depolarization and attenuated the movement-related activity similar to the firing pattern observed in rats for successful action suppression. We conclude that arkypallidal Stop responses can suppress movement-related activity in the striatum by suppressing the dendritic plateau potentials.