Fronto-parietal Cortical Circuits Encode Accumulated Evidence with a Diversity of Timescales

Neuron. 2017 Jul 19;95(2):385-398.e5. doi: 10.1016/j.neuron.2017.06.013. Epub 2017 Jun 29.


Decision-making in dynamic environments often involves accumulation of evidence, in which new information is used to update beliefs and select future actions. Using in vivo cellular resolution imaging in voluntarily head-restrained rats, we examined the responses of neurons in frontal and parietal cortices during a pulse-based accumulation of evidence task. Neurons exhibited activity that predicted the animal's upcoming choice, previous choice, and graded responses that reflected the strength of the accumulated evidence. The pulsatile nature of the stimuli enabled characterization of the responses of neurons to a single quantum (pulse) of evidence. Across the population, individual neurons displayed extensive heterogeneity in the dynamics of responses to pulses. The diversity of responses was sufficiently rich to form a temporal basis for accumulated evidence estimated from a latent variable model. These results suggest that heterogeneous, often transient sensory responses distributed across the fronto-parietal cortex may support working memory on behavioral timescales. VIDEO ABSTRACT.

Keywords: accumulation of evidence; calcium imaging; decision-making; drift diffusion model; head restraint; multiphoton fluorescence microscopy; neocortex; neural coding; rodent; working memory.

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Behavior, Animal / physiology
  • Choice Behavior / physiology*
  • Decision Making / physiology*
  • Frontal Lobe / physiology*
  • Memory, Short-Term / physiology*
  • Neurons / physiology*
  • Parietal Lobe / physiology*
  • Rats
  • Time Factors