Ensembles code for associative learning in the primate lateral prefrontal cortex
Alireza Rouzitalab,
Chadwick B. Boulay,
Jeongwon Park,
Julio C. Martinez-Trujillo,
Adam J. Sachs
Affiliations
Alireza Rouzitalab
School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 9A7, Canada; The Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada; Corresponding author
Chadwick B. Boulay
The Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada; Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
Jeongwon Park
School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 9A7, Canada; Department of Electrical and Biomedical Engineering, University of Nevada, Reno, NV 89557, USA
Julio C. Martinez-Trujillo
Department of Physiology and Pharmacology and Psychiatry, and Western Institute for Neuroscience, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A 5K8, Canada; Corresponding author
Adam J. Sachs
The Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada; Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Corresponding author
Summary: The lateral prefrontal cortex (LPFC) of primates is thought to play a role in associative learning. However, it remains unclear how LPFC neuronal ensembles dynamically encode and store memories for arbitrary stimulus-response associations. We recorded the activity of neurons in LPFC of two macaques during an associative learning task using multielectrode arrays. During task trials, the color of a symbolic cue indicated the location of one of two possible targets for a saccade. During a trial block, multiple randomly chosen associations were learned by the subjects. A state-space analysis indicated that LPFC neuronal ensembles rapidly learn new stimulus-response associations mirroring the animals’ learning. Multiple associations acquired during training are stored in a neuronal subspace and can be retrieved hours after learning. Finally, knowledge of old associations facilitates learning new, similar associations. These results indicate that neuronal ensembles in the primate LPFC provide a flexible and dynamic substrate for associative learning.
