The neurophysiology of decision making: rate differences and log likelihood ratios

With little sophistication, the spike rates from sensory neurons can be used to approximate useful statistics for decision making. In the context of deciding between two sensory hypotheses, a simple difference in spike rate between sensory neurons with opposite selectivity is proportional to the log likelihood ratio in favor of one sensory interpretation over another. I will describe neural recording and stimulation experiments from the alert monkey that demonstrate that the brain uses such a difference to make decisions about the direction of motion in a 2-alternative direction discrimination task. The accumulation of this difference to threshold explains the speed and accuracy of simple decisions. I will attempt to address the question of how general is the approximation to log likelihood ratio and what this might mean for neural coding in general.

Speaker Details

Dr. Shadlen is Associate Professor of Physiology and Biophysics and Core Staff Scientist of the Regional Primate Research Center at the University of Washington. He received his B.A. degree in biology and his M.D. degree from Brown University. He received his Ph.D. degree from the University of California, Berkeley, where he studied with Ralph Freeman. His residency training in neurology was completed at Stanford University Medical Center. Dr. Shadlen returned to research as a Howard Hughes postdoctoral research fellow in William Newsome’s laboratory at Stanford.

Date:
Speakers:
Michael Shadlen
Affiliation:
HHMI and University of Washington