The sensory neurons of touch


February 19, 2015 - 12:00pm
NW B103
About the Speaker
David Ginty (Harvard Medical School)

The somatosensory system endows us with a remarkable capacity for object recognition, texture discrimination, sensory-motor feedback, and social exchange. Innocuous touch of the skin is detected by a large group of physiologically distinct low-threshold mechanoreceptors (LTMRs) whose cell bodies are located in dorsal root ganglia and cranial ganglia. We have generated a mouse LTMR molecular-genetic toolbox that enables interrogation of the physiology, morphology, function, and development of each LTMR subtype. Using these genetic tools and anatomical and physiological approaches, we have defined developmental, morphological and functional properties of LTMRs. We also observed that LTMR subtypes whose peripheral projections innervate the same small region of skin exhibit central projections that terminate within narrow, three-dimensional columns of the spinal cord dorsal horn. These spinal cord LTMR columns represent units of functional organization that receive and process LTMR subtype activity ensembles emanating from the skin. We further posit that spinal cord interneurons directly receive and process LTMR activities, whereas spinal cord projection neurons carry processed touch information from spinal cord LTMR columns to the brain. To test these ideas and to gain insight into touch information processing in the spinal cord, we recently generated an array of spinal cord dorsal horn neuron subtype-specific molecular genetic tools that enable functional characterization of spinal cord dorsal horn neuronal populations. Tools that enable analysis of 11 distinct spinal cord interneuron subtypes are being used to elucidate the development, physiological properties, morphologies, synaptic connectivity patterns, and functions of spinal cord interneuron subtypes. LTMR subtypes functions, development and organization, and mechanisms of touch information processing in the spinal cord, are the current topics of focus.