Dichotomous activity and function of neurons with low- and high-frequency discharge in the external globus pallidus of non-human primates

To date, there is a consensus that there are at least two neuronal populations in the non-human primate (NHP) external globus pallidus (GPe): low-frequency discharge (LFD) and high-frequency discharge (HFD) neurons. Nevertheless, almost all NHP physiological studies have neglected the functional importance of LFD neurons. This study examined the discharge features of these two GPe neuronal subpopulations recorded in four NHPs engaged in a classical conditioning task with cues predicting reward, neutral and aversive outcomes. The results show that LFD neurons tended to burst, encoded the salience of behavioral cues, and exhibited correlated spiking activity. By contrast, the HFD neurons tended to pause, encoded cue valence, and exhibited uncorrelated spiking activity. Overall, these findings point to the dichotomic organization of the NHP GPe, which is likely to be critical to the implementation of normal basal ganglia functions and computations. [Display omitted] •Two neuronal populations co-exist in the external globus pallidus of non-human primates•Low- and high-frequency discharge neurons exhibit dichotomic activity and coding•Low-frequency discharge neurons burst, encode salience, and show correlated activity•High-frequency discharge neurons pause, encode valence, and show independent activity Katabi et al. report neuronal and functional heterogeneity in the external globus pallidus of non-human primates engaged in a classical conditioning task. They identify two neuronal subpopulations with distinct spontaneous and task-related discharge features that may play a specific role in normal basal ganglia functions and computations.