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Inhibitory Shaping of Sensory Signals during Active Touch

When Feb 01 2017 12:00 EST
Where Mellon Institute Conference Room
Who Jianing Yu, PhD

Postdoctoral Associate Laboratory of Dr. Karel Svoboda HHMI Janelia Research Campus

Abstract: Active movements of sensors, such as digits and limbs, are essential for animals to interact with the external environment. Movement itself produces sensory signals, known as reafference, which are intertwined with sensory input evoked by touch with external objects. To disentangle sensory signals coming from touch versus self-movement, the brain likely exploits tactile suppression, which describes that the sensitivity to sensory input is reduced in the cortex during movement. Tactile suppression reduces predicable sensory signals associated with self-movement and facilitates signals related to novel events such as external contacts. It has long been thought that movement-induced sensory suppression arises from central sources in the brain associated with movement generation. Here, however, we discovered that fast-spiking inhibitory interneurons in the vibrissal somatosensory cortex are driven by self-initiated whisker movement, which depends on the sensory reafference and is mediated by the thalamocortical pathway. The inhibition then suppresses movement-related input to excitatory neurons such that the spikes in excitatory neurons mainly represent touch. The functional property of fast-spiking interneurons is endowed by their strong connection with the thalamocortical inputs, which carry both touch and self-movement activities. In contrast, a different type of interneurons, namely somatostatin-expressing interneurons, which are only weakly connected to the thalamocortical inputs, show selective response to touch but not whisker movement. Thus, inhibitory interneurons in the cortical circuits are assembled such that different types shape different aspects of sensory representation during active touch.