[Seminar] "The Many Layers of Touch" by Randy M. Bruno, Ph.D
The neocortex mediates all of human and animal cognition—breathtakingly encompassing sensation, perception, decision making, and movement. These diverse functions are achieved by highly stereotyped circuitry that nature appears to have iterated across the entire surface of the brain. Recently we discovered that ascending signals from thalamus are copied separately to the superficial and deep layers of sensory cortex. Despite dense connections between layers, ascending thalamic signals account for all the sensory-driven activity of the deep layers. I will present our latest anatomical and physiological results demonstrating independence of these two sets of layers as well as possible mechanisms for gating their interactions. We are presently investigating the necessity of the primary somatosensory cortex and its constituent layers in tactile object recognition. I will show how modern optogenetic and older lesion approaches can lead to radically different conclusions about necessity of a brain structure to a behavior. We have found that sensory cortex is dispensable for learning and performing some of the field’s most widely used behavioral paradigms. This underscores the competency of subcortical systems at basic behavioral tasks and suggests alternative mechanisms for how cortex contributes to complex behavior.
Acknowledgements: Funded by NIH/NIDCD R01-DC2390, the Canadian Institutes of Health Research (CIHR), Natural Sciences and Engineering Research Council of Canada (NSERC), and Canada Foundation for Innovation (CFI).
Randy Bruno is a Principal Investigator at Columbia University and the Zuckerman Mind Brain Behavior Institute. He earned his Ph.D. in Neurobiology with Professor Daniel J. Simons at the University of Pittsburgh School of Medicine and performed postdoctoral research with the Nobel laureate Bert Sakmann at the Max Planck Institute for Medical Research in Heidelberg, Germany. Professor Bruno’s own laboratory investigates how the circuitry of the thalamus and cerebral cortex enables sensation, perception, and decision making. His lab discovered that the upper layers and deep layers of the cortex comprise two separate systems, which can operate independently. This work earned him the Society for Neuroscience’s 2013 Young Investigator Award. His major current efforts are to understand the computational and behavioral roles of these two halves of the cortex and the role of the secondary somatosensory thalamus in modulation cortical computation.