Neuronal Activity Dependent on Anticipated and Elapsed Delay in Macaque Prefrontal Cortex, Frontal and Supplementary Eye Fields, and Premotor Cortex

• Published in: Journal of neurophysiology 2005-08, Vol.94 (2), p.1469-1497
• Main Authors: Roesch, Matthew R, Olson, Carl R
• Format: Article
• Language: English
• Subjects: Animals; Brain Mapping; Electric Stimulation - methods; Electromyography; Frontal Lobe - cytology; Frontal Lobe - physiology; Functional Laterality; Macaca; Macaca mulatta; Magnetic Resonance Imaging; Male; Memory - physiology; Muscle, Skeletal - physiology; Muscle, Skeletal - radiation effects; Neurons - classification; Neurons - physiology; Ocular Physiological Phenomena; Photic Stimulation - methods; Reaction Time; Reward; Time Factors; Visual Fields - physiology; Visual Perception - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00064.2005

Center for the Neural Basis of Cognition, Mellon Institute; and Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania Submitted 19 January 2005; accepted in final form 27 March 2005 In macaque monkeys performing a memory-guided saccade task for a reward of variable size, neuronal activity in several areas of frontal cortex is stronger when the monkey anticipates a larger reward. This effect might depend on either the size or the value of the reward. To distinguish between these possibilities, we recorded from neurons in frontal cortex while controlling value through a manipulation of time rather than amount. A cue presented at the beginning of each trial, predicted the length of the delay during which the monkey would have to maintain fixation before performing a saccade and receiving a reward of fixed size. Predicting a short delay had effects closely similar to those of predicting a large reward: 1 ) monkeys were more motivated when working for a reward at short delay, 2 ) neurons tended to fire more strongly before a short delay, 3 ) individual neurons firing more strongly before a short delay tended also to fire more strongly before a large reward, and 4 ) the tendency to fire more strongly before a short delay was far more pronounced in premotor areas caudal to the arcuate sulcus than in association areas rostral to it. The association areas, in contrast, were marked by a tendency for neurons to fire more strongly at the end of the long delay. We conclude that predicting a short delay, like predicting a large reward, induces an enhancement of neuronal activity related to motivational modulation of the monkey's preparatory state. Address for reprint requests and other correspondence: M. R. Roesch, University of Maryland School of Medicine, Department of Anatomy and Neurobiology, HSF-2, Room S251, 20 Penn Street, Baltimore, MD 21201 (E-mail: mroes001{at}umaryland.edu )