题目：Behavior-relevant inhibition and its role in circuit computation during active somatosensation
HHMI Janelia Research Campus
Neural circuits in the neocortex are comprised of multiple types of excitatory and inhibitory neurons. Different types of neurons form specific connections with long-range afferent inputs as well as with each other. Three questions naturally arise: What are the cell types in the cortical circuits? How are different types of neurons connected? How does the connectivity give rise to cell type-specific firing patterns and functions during information processing?
I approach these questions in the whisker somatosensory system of behaving mice that are trained to perform whisker-dependent tactile tasks. Guided by optogenetic tagging, I recorded the electrical activity of defined types of excitatory neurons and inhibitory interneurons in the whisker somatosensory cortex—using both extracellular and intracellular recording techniques—and related the neuronal activity to behavioral events such as movement and touch. My work demonstrated that cortical fast-spiking inhibitory interneurons act as a narrow gate at the entrance of somatosensory cortex, allowing touch-evoked synchronous signals to be transmitted from the thalamus to the cortex while suppressing slowly-varying signals associated with self-movement. In contrast, cortical somatostatin-expressing inhibitory interneurons provide a temporally-delayed inhibition that follows the touch-evoked activity of local excitatory neurons. The distinct functions of these two major types of cortical inhibitory interneurons are closely tied to the differential patterns by which they are connected to the thalamocortical and intracortical circuits.
Looking to the future, I believe cell type-specific neurophysiology holds great promise for linking the synaptic organization of neural circuits to the intricate activity patterns and precise functions of neurons during behavior. With tools to target specific cell types and manipulate the activity of neurons or neural pathways, we are at an exciting time to dissect the neural circuits underlying sensation, movement and cognitive functions in behaving animals.