Abstract
Given a noisy sensory world, the nervous system integrates perceptual evidence over time to optimize decision-making. Neurophysiological accumulation of sensory information is well-documented in the animal visual system, but how such mechanisms are instantiated in the human brain remains poorly understood. Here we combined psychophysical techniques, drift-diffusion modeling, and functional magnetic resonance imaging (fMRI) to establish that odor evidence integration in the human olfactory system enhances discrimination on a two-alternative forced-choice task. Model-based measures of fMRI brain activity highlighted a ramp-like increase in orbitofrontal cortex (OFC) that peaked at the time of decision, conforming to predictions derived from an integrator model. Combined behavioral and fMRI data further suggest that decision bounds are not fixed but collapse over time, facilitating choice behavior in the presence of low-quality evidence. These data highlight a key role for the orbitofrontal cortex in resolving sensory uncertainty and provide substantiation for accumulator models of human perceptual decision-making.
Original language | English (US) |
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Pages (from-to) | 916-927 |
Number of pages | 12 |
Journal | Neuron |
Volume | 75 |
Issue number | 5 |
DOIs | |
State | Published - Sep 6 2012 |
Funding
We thank J. Antony for assistance with Experiment 1, J.D. Howard and K.N. Wu for methodological assistance, and T. Egner, A. Kepecs, and D. Rinberg for comments on earlier drafts of the manuscript. This work was supported by grants to J.A.G. from the National Institute on Deafness and Other Communication Disorders (K08DC007653, R01DC010014, and R21DC012014), grants to K.P.K. from the National Institute of Neurological Diseases and Stroke (R01NS063399 and P01NS044393), and a training grant to N.E.B. from the National Institutes of Health (T32 AG20506). N.E.B. and J.A.G. conceived the study and designed the experiments; N.E.B. performed the experiments; all authors analyzed the data, prepared the figures, and wrote the manuscript.
ASJC Scopus subject areas
- General Neuroscience