Columnar scale lesions in barrel cortex degrade tactile discrimination but not detection

Abstract

Primary sensory cortices typically display functional topography, suggesting that even small cortical volumes may underpin perception of specific stimuli. Because traditional loss-of-function approaches have a relatively large radius of effect (>1 mm), the behavioral necessity of smaller cortical volumes remains unclear. In the mouse primary vibrissal somatosensory cortex (vS1), 'barrels' with a radius of ~150 μm receive input predominantly from a single whisker, partitioning vS1 into a topographic map of well- defined columns. Here, we train animals implanted with a cranial window over vS1 to perform single-whisker perceptual tasks. We then use high-power laser exposure centered on the barrel representing the spared whisker to produce lesions with an average volume of ~2 barrels. These columnar scale lesions impair performance on object location discrimination tasks without disrupting vibrissal kinematics. Animals with degraded discrimination performance can immediately perform a detection task with high accuracy. Animals trained de novo on both simple and complex detection tasks showed no behavioral deficits following columnar scale lesions. Thus, vS1 barrels are necessary for performing object location discrimination but not simple or complex object detection