title: A neural mechanism of speed-accuracy tradeoff in macaque area LIP.
abstract: Decision making often involves a tradeoff between speed and accuracy. Previous studies indicate that neural activity in the lateral intraparietal area (LIP) represents the gradual accumulation of evidence toward a threshold level, or evidence bound, which terminates the decision process. The level of this bound is hypothesized to mediate the speed-accuracy tradeoff. To test this, we recorded from LIP while monkeys performed a motion discrimination task in two speed-accuracy regimes. Surprisingly, the terminating threshold levels of neural activity were similar in both regimes. However, neurons recorded in the faster regime exhibited stronger evidence-independent activation from the beginning of decision formation, effectively reducing the evidence-dependent neural modulation needed for choice commitment. Our results suggest that control of speed vs accuracy may be exerted through changes in decision-related neural activity itself rather than through changes in the threshold applied to such neural activity to terminate a decision.
authors.affiliation: Princeton Neuroscience Institute, Princeton University, Princeton, United States.
authors.forename: Timothy
authors.initials: T
authors.lastname: Hanks
authors.affiliation: Center for Neural Science, New York University, New York, United States.
authors.forename: Roozbeh
authors.initials: R
authors.lastname: Kiani
authors.affiliation: Department of Neuroscience, Howard Hughes Medical Institute, Columbia University, New York, United States.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Shadlen
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D001522:Behavior, Animal; D002755:Choice Behavior; D003657:Decision Making; D008251:Macaca; D008959:Models, Neurological; D009039:Motion Perception; D009474:Neurons / Q000502:physiology*; D009482:Neurophysiology; D010775:Photic Stimulation; D011930:Reaction Time; D015203:Reproducibility of Results; D013997:Time Factors
keywords: decision making; neuroscience; parietal cortex; rhesus macaque monkey; speed-accuracy tradeoff