title: Representation of accumulating evidence for a decision in two parietal areas.
abstract: Decisions are often made by accumulating evidence for and against the alternatives. The momentary evidence represented by sensory neurons is accumulated by downstream structures to form a decision variable, linking the evolving decision to the formation of a motor plan. When decisions are communicated by eye movements, neurons in the lateral intraparietal area (LIP) represent the accumulation of evidence bearing on the potential targets for saccades. We now show that reach-related neurons from the medial intraparietal area (MIP) exhibit a gradual modulation of their firing rates consistent with the representation of an evolving decision variable. When decisions were communicated by saccades instead of reaches, decision-related activity was attenuated in MIP, whereas LIP neurons were active while monkeys communicated decisions by saccades or reaches. Thus, for decisions communicated by a hand movement, a parallel flow of sensory information is directed to parietal areas MIP and LIP during decision formation.
authors.affiliation: Institute of Neurobiology, National University of Mexico, 76230 Querétaro, México, Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195.
authors.forename: Victor
authors.initials: V
authors.lastname: de Lafuente
authors.affiliation: Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Jazayeri
authors.affiliation: Howard Hughes Medical Institute, Zuckerman Mind Brain Behavior, Kavli Institute and Department of Neuroscience, Columbia University, New York, New York 10038, and Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195 shadlen@columbia.edu.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Shadlen
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D003657:Decision Making / Q000502:physiology*; D004192:Discrimination, Psychological; D005133:Eye Movements; D007839:Functional Laterality / Q000502:physiology*; D007600:Judgment; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception; D009474:Neurons / Q000502:physiology*; D010296:Parietal Lobe / Q000166:cytology* / Q000502:physiology*; D010775:Photic Stimulation; D011594:Psychometrics; D011597:Psychomotor Performance / Q000502:physiology; D011601:Psychophysics; D013997:Time Factors
keywords: LIP; MIP; decision-making; reaches; saccades; sensory