Cortical neurons multiplex reward-related signals along with sensory and motor information.
Abstract
Rewards are known to influence neural activity associated with both motor preparation
and execution. This influence can be exerted directly upon the primary motor (M1)
and somatosensory (S1) cortical areas via the projections from reward-sensitive dopaminergic
neurons of the midbrain ventral tegmental areas. However, the neurophysiological manifestation
of reward-related signals in M1 and S1 are not well understood. Particularly, it is
unclear how the neurons in these cortical areas multiplex their traditional functions
related to the control of spatial and temporal characteristics of movements with the
representation of rewards. To clarify this issue, we trained rhesus monkeys to perform
a center-out task in which arm movement direction, reward timing, and magnitude were
manipulated independently. Activity of several hundred cortical neurons was simultaneously
recorded using chronically implanted microelectrode arrays. Many neurons (9-27%) in
both M1 and S1 exhibited activity related to reward anticipation. Additionally, neurons
in these areas responded to a mismatch between the reward amount given to the monkeys
and the amount they expected: A lower-than-expected reward caused a transient increase
in firing rate in 60-80% of the total neuronal sample, whereas a larger-than-expected
reward resulted in a decreased firing rate in 20-35% of the neurons. Moreover, responses
of M1 and S1 neurons to reward omission depended on the direction of movements that
led to those rewards. These observations suggest that sensorimotor cortical neurons
corepresent rewards and movement-related activity, presumably to enable reward-based
learning.
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https://hdl.handle.net/10161/15773Published Version (Please cite this version)
10.1073/pnas.1703668114Publication Info
Ramakrishnan, Arjun; Byun, Yoon Woo; Rand, Kyle; Pedersen, Christian E; Lebedev, Mikhail
A; & Nicolelis, Miguel AL (2017). Cortical neurons multiplex reward-related signals along with sensory and motor information.
Proc Natl Acad Sci U S A, 114(24). pp. E4841-E4850. 10.1073/pnas.1703668114. Retrieved from https://hdl.handle.net/10161/15773.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Miguel Angelo L. Nicolelis
Duke School of Medicine Distinguished Professor in Neuroscience
Miguel Nicolelis, M.D., Ph.D., is the Duke School of Medicine Distinguished Professor
of Neuroscience, Duke University Professor of Neurobiology, Biomedical Engineering
and Psychology and Neuroscience, and founder of Duke's Center for Neuroengineering.
He is the founder and Scientific Director of the Edmond and Lily Safra International
Institute for Neuroscience of Natal. Dr. Nicolelis is also founder of the Walk Again
Project, an international consortium of scientists and engineers, de

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