AUTHOR=Ramayya Ashwin G. , Pedisich Isaac , Levy Deborah , Lyalenko Anastasia , Wanda Paul , Rizzuto Daniel , Baltuch Gordon H. , Kahana Michael J. TITLE=Proximity of Substantia Nigra Microstimulation to Putative GABAergic Neurons Predicts Modulation of Human Reinforcement Learning JOURNAL=Frontiers in Human Neuroscience VOLUME=Volume 11 - 2017 YEAR=2017 URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2017.00200 DOI=10.3389/fnhum.2017.00200 ISSN=1662-5161 ABSTRACT=

Neuronal firing in the substantia nigra (SN) immediately following reward is thought to play a crucial role in human reinforcement learning. As in Ramayya et al. (2014a) we applied microstimulation in the SN of patients undergoing deep brain stimulation (DBS) for the treatment of Parkinson's disease as they engaged in a two-alternative reinforcement learning task. We obtained microelectrode recordings to assess the proximity of the electrode tip to putative dopaminergic and GABAergic SN neurons and applied stimulation to assess the functional importance of these neuronal populations for learning. We found that the proximity of SN microstimulation to putative GABAergic neurons predicted the degree of stimulation-related changes in learning. These results extend previous work by supporting a specific role for SN GABA firing in reinforcement learning. Stimulation near these neurons appears to dampen the reinforcing effect of rewarding stimuli.