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Over the past few decades, genomic and molecular research has produced new understandings of the cellular mechanisms that contribute to brain function and behavior. We are interested in linking cellular mechanisms to behavior at the organismís level via the processing of sensory information by neural populations. To do so, we use a well-established lower vertebrate model system that shows many similarities with higher vertebrates such as humans: weakly electric fish. Research on weakly electric fish benefits from easily described and stereotyped behavior, relatively simple anatomy, and well-characterized physiology.

Neuromodulation of sensory processing:

There are important neuromodulatory pathways in sensory areas including: dopaminergic, neuradrenergic, cholinergic, and serotonergic. We are interested in how serotonergic pathways originating from the Raphe Nucleus can affect a sensory neuron's response to incoming stimuli. We use electrophysiological approaches in both brain slices and in whole animals to address the following questions: 1) what are the cellular mechanisms by which serotonergic projections modulate excitability in sensory neurons. 2) Do these mechanisms operate in whole animals? 3) How will activation of serotonergic pathways affect responses to sensory input in whole animals

Population coding by pyramidal cells:

As in any good democracy, the single neuron has no voice and it is instead the activity from large populations of neurons that mediate behavior. For this reason, Investigators have started to record simultaneously from many neurons. In particular, there is a lot of interest in understanding how synchrony (i.e. the tendency for multiple neurons to fire action potentials at the same time). We have found that neighboring pyramidal neurons tended to display synchrony and are currently investigating how sensory stimulation affects this synchrony.

Sparsening of neural codes in midbrain:

It is well known that neurons become more selective yet invariant in high brain areas. For example, neurons in area V4 of the primate visual cortex will respond to a blue cup but not a red cup, even though the cups have the same shape (i.e. this neuron was selective to color). The cellular mechanisms that underlie this selectivity are poorly understood. We are studying the response properties of midbrain neurons (i.e. neurons that receive direct input from pyramidal cells) to sensory stimuli in order to address this question.