David J. Pinto
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Assistant Professor
- Biomedical Engineering
- Neurobiology & Anatomy
Research Overview
A clear understanding of the relationship and transitions between normal and pathological brain functions is a vital step toward learning to restore the system when things go wrong. In the brain's neocortex, the same basic neuronal circuits that control the normal functions of sensation and reasoning are also involved in the pathological functions of epilepsy and schizophrenia. Brain circuits are assembled from a variety of distinct neuronal and synaptic elements. The goal of my research program is to discover the mechanisms by which those elements interact to govern and constrain both normal and pathological functions exhibited by brain circuits in neocortex. My principal research strategy is to explore the mechanisms underlying each function using an approach that combines computational modeling, mathematical analysis, and both in vivo and in vitro experimental techniques. At present, the focus of my research is on the biological mechanisms of sensation. More particularly, I am studying the sense of touch and the mechanisms of texture discrimination using the rodent whisker system as an animal model.
The whisker system is uniquely suited for the study of brain function during sensation. Using only their whiskers, rats can discriminate texture nearly as well as humans can using their fingertips. Each whisker on the rat's face sends information to discrete and identifiable neuronal circuits in the brain called whisker barrels. This arrangement allows for exquisite control over the spatial and temporal extent of brain activation; I can activate barrel circuits alone or in groups simply by wiggling one or more whiskers together or in sequence. Anatomically, the rodent brain also facilitates a living brain slice preparation that retains several of the barrel circuits. This reduced preparation allows access to individual components of the barrel circuit and enables a detailed analysis of how each element contributes to the function of the circuit as a whole that is not available using the intact-animal preparation.
My current investigation into sensation employs methods from many disciplines. First, using infrared microscopy and glass microelectrodes to visualize and record from living brain cells, I examine the responses of individual and small groups of sensory neurons to signals that approximate natural stimuli. Second, using real-time computer simulations, I embed those same living neurons into circuits of virtual neurons of increasing complexity; real and simulated neurons interact by means of electrical currents passed through the glass electrodes. This technique allows me to compare directly the responses of the same neuron when acting alone, within a microcircuit of a few neurons, and within a local circuit of hundreds or thousands of neurons. Third, using mathematical techniques from dynamical systems analysis and information theory, I dissect the responses of both real and simulated neurons to understand how individual neurons contribute to the ensemble responses of the circuits and, conversely, how circuits sculpt the responses of individual neurons.