Causal role for the primate superior colliculus in the computation of evidence for perceptual decisions

Nat Neurosci. 2021 Aug;24(8):1121-1131. doi: 10.1038/s41593-021-00878-6. Epub 2021 Jun 28.


Trained monkeys performed a two-choice perceptual decision-making task in which they reported the perceived orientation of a dynamic Glass pattern, before and after unilateral, reversible, inactivation of a brainstem area-the superior colliculus (SC)-involved in preparing eye movements. We found that unilateral SC inactivation produced significant decision biases and changes in reaction times consistent with a causal role for the primate SC in perceptual decision-making. Fitting signal detection theory and sequential sampling models to the data showed that SC inactivation produced a decrease in the relative evidence for contralateral decisions, as if adding a constant offset to a time-varying evidence signal for the ipsilateral choice. The results provide causal evidence for an embodied cognition model of perceptual decision-making and provide compelling evidence that the SC of primates (a brainstem structure) plays a causal role in how evidence is computed for decisions-a process usually attributed to the forebrain.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Decision Making / physiology*
  • Macaca mulatta
  • Male
  • Models, Neurological*
  • Neurons / physiology
  • Superior Colliculi / physiology*