A spiking model of the basal ganglia demonstrates several complementary movement-cancellation mechanisms
Oliver Maith 
Fred Hamker
How do we hold back or rapidly cancel actions? A common method to study this ability is the stop-signal task, in which an action is to be performed after a stimulus cue and rapidly canceled after an occasional, second, delayed stimulus. Behavioral performance in this task is generally well described by a theoretical race model in which separate “go” and “stop” processes compete. At a brain-mechanism level, recent findings indicate that the race between these “go” and “stop” processes may be decided in the basal ganglia. However, the exact mechanisms are not yet clear.
In this computational study (Goenner et al., 2021), we have aimed to gain a better understanding of the details about action cancellation-related dynamics within the basal ganglia. Based on recent experimental findings, we have extended our spiking basal ganglia model, especially by dividing the external globus pallidus (GPe) into three sub-neuron populations: prototypical, arkypallidal, and cortex-projecting neurons. As we validated the network dynamics during a simulated stop-signal task with recent experimental data from Mallet et al. (2016), our model is consistent with the Pause-then-Cancel model of Schmidt & Berke (2017), which proposes that, the response of arkypallidal neurons after a stop-related stimulus cue induces action cancellation, after a pause-evoking response of the subthalamic nucleus.
By performing various manipulations on the model and studying the effects on behavioral performance and neuronal activity, we were able to investigate more detailed mechanisms. Our model proposes that the stop-related responses of subthalamic and arkypallidal neurons must be complemented by cortex-projecting neurons of the GPe that suppress go-related cortical processes. Further, regarding the detailed function of arkypalldial neurons, our model surprisingly predicts that inhibition of striatal projection neurons of the indirect pathway of the basal ganglia is essential for action cancellation, rather than the inhibition of the direct pathway, which usually is responsible for action initiation. Finally, our model results can reconcile the initially seemingly contradictory findings on the responses of GPe-neurons during movement cancellation and movement initiation and relate them to the previously observed biphasic nature of movement-related responses in GPe-neurons, which in our model are caused by simultaneous inhibitory striatal and excitatory cortical input.
Back to topMaith, O., & Hamker, F. (2022). A spiking model of the basal ganglia demonstrates several complementary movement-cancellation mechanisms. Bernstein Conference 2022. doi: 10.12751/nncn.bc2022.188