Citation

Felsen G, Mainen ZF. J. Neurophysiol. 2012; 108(1): 135-147.

Affiliation

Univ. Colorado, School of Medicine.

Copyright

(Copyright © 2012, American Physiological Society)

DOI

10.1152/jn.01181.2011

PMID

22496524

Abstract

Making decisions about future actions is a fundamental function of the nervous system. Classical theories hold that separate sets of brain regions are responsible for selecting and implementing an action. Traditionally, action selection has been considered the domain of high-level regions such as the prefrontal cortex, while action generation is thought to be carried out by dedicated cortical and subcortical motor regions. However, increasing evidence suggests that the activity of individual neurons in cortical motor structures reflects abstract properties of "decision variables" rather than conveys simple motor commands. Less is known, though, about the role of subcortical structures in decision making. In particular, the superior colliculus (SC) is critical for planning and initiating visually-guided gaze-displacing movements, and selecting visual targets, but whether and how it contributes more generally to sensorimotor decisions is unclear. Here, we show that the SC is intimately involved in orienting decisions based on odor cues, even though the SC does not explicitly process olfactory stimuli. Neurons were recorded from the intermediate and deep SC layers in rats trained to perform a delayed-response odor-cued spatial choice task. SC neurons commonly fired well in advance of movement initiation, predicting the chosen direction nearly one second before movement. Moreover, under conditions of sensory uncertainty, SC activity varied with task difficulty and reward outcome, reflecting the influence of decision variables on the intercollicular competition thought to underlie orienting movements. These results indicate that the SC plays a more general role in decisions than previously appreciated, extending beyond visuomotor functions.

Language: en