Neuronal Cooperativity in the Somatosensory System

Individual neurons in the nervous system use electrical impulses or action potentials to communicate sensory information from one region of the brain to another region. This project is concerned with determining how neurons in the somatosensory part of the thalamus communicate with neurons in the somatosensory part of the cerebral cortex during tactile stimulation. More specifically, we wish to measure how the relative timing of action potentials among neighboring thalamic neurons might alter the responsiveness of neurons in the cerebral cortex. Many neuroscientists believe that cortical neurons are likely to respond with an action potential when they receive communication from multiple thalamic neurons at the same time but are less likely to respond if they receive communication from only one thalamic neuron. We will directly test this hypothesis by inserting multiple electrodes into both brain regions and recording the precise times of their neuronal action potentials when the skin is touched by a computer controlled air puff. We will use statistical analysis to determine if the probability of a cortical action potential is highest when pairs of thalamic neurons discharge at the same time (in synchrony) or at different times (asynchronously). We will also use our computer controlled air puffer to stimulate the skin in a variety of spatiotemporal configurations to determine which types of tactile stimuli are best for activating pairs of thalamic neurons at the same time. We will also use this method to determine which tactile stimuli activate pairs of cortical neurons at the same time. This research project is important because it will determine if neuronal synchronization is a mechanism used by the brain to communicate information from one brain region to the next. This project will also provide evidence suggesting whether neuronal synchronization could be used by the brain to represent certain types of sensory stimuli. Hence, when this project is completed, we will know how individual cortical neurons respond to simultaneous inputs and this will greatly increase our understanding of how neuronal circuits operate in the mammalian brain.