Early Planning Activity in Frontal and Parietal Cortex in a Simplified Task
Cortical planning activity has traditionally been probed with visual targets. However, external sensory signals might obscure early correlates of internally generated plans. We devised a non-spatial decision-making task, in which the monkey is encouraged to randomly decide whether to reach or saccade, in the absence of sensory stimuli. Neurons in frontal and parietal planning areas (in and around the arcuate and intraparietal sulci) showed responses predictive of the monkey's upcoming movement at early stages during the planning process. Neurons predicted the animal's future movements several seconds beforehand, sometimes before the trial even began. These data cast new light on the role of the cerebral cortex in the action planning process, when the animal is free to decide on his own actions in the absence of extraneous sensory cues.
© 2014 Journal of Neurophysiology. Submitted 4 February 2014. Revision received 6 March 2015. Accepted 6 March 2015. Published 11 March 2015. We thank Xoana Troncoso and Boris Revechkis for helpful discussions, Viktor Shcherbatyuk for computer support, Tessa Yao for administrative support, and Kelsie Pejsa and Carina Gonzalez for help with animal handling and training. Support: The Swartz Foundation, the National Eye Institutes (R01 EY007492), the Conte Foundation (P50 MH094258).