Making sense of sensory evidence in the rat whisker system.

In natural environments, choices frequently must be made on the basis of complex and ambiguous streams of sensory input. There are advantages inherent to rapid decision making. Choices are better grounded, however, if information is acquired and accumulated over time. In primate visual motion perception, sensory evidence is accumulated up to a limit, at which point the brain commits to a choice. Recalling the models evoked for primate visual perception, recent studies in the rat vibrissal sensorimotor system, using a number of behavioral paradigms, show that perceptual decision making is characterized by the integration of sensory evidence over time. In this integrative process, vibrissal primary somatosensory cortex (vS1 and vS2) act not as the integrator, but as the distributor of sensory information to downstream regions.