Single-trial spike trains in parietal cortex reveal discrete steps during decision-making
Abstract
Neurons in the macaque lateral intraparietal (LIP) area exhibit firing rates that appear to ramp upward or downward during decision-making. These ramps are commonly assumed to reflect the gradual accumulation of evidence toward a decision threshold. However, the ramping in trial-averaged responses could instead arise from instantaneous jumps at different times on different trials. We examined single-trial responses in LIP using statistical methods for fitting and comparing latent dynamical spike-train models. We compared models with latent spike rates governed by either continuous diffusion-to-bound dynamics or discrete “stepping” dynamics. Roughly three-quarters of the choice-selective neurons we recorded were better described by the stepping model. Moreover, the inferred steps carried more information about the animal’s choice than spike counts.
- Publication:
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Science
- Pub Date:
- July 2015
- DOI:
- 10.1126/science.aaa4056
- Bibcode:
- 2015Sci...349..184L
- Keywords:
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- NEUROSCIENCE