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.