Christopher B. Braun
We study sensory function in aquatic animals by measuring behaviorally relevant psychophysical and physiological indices of stimulus detection. The questions we ask can all be paraphrased: what information does this sense provide the nervous system? Our approach is to compare measures of sensory function (detection, discrimination, filter properties, etc.) in species that differ in structural, behavioral or ecological detail. We also make parallel comparisons between sensory modalities that are responsive to overlapping sets of stimuli.
Our current investigations focus on the senses fish use to detect moving and sound-producing objects. We want to know what some fish can hear that others can not. Fishes have multiple sensory systems that respond to these kinds of sources, what can some modalities detect that others can not? We are also applying our comparative approach to the neural control of an active sense, the electrogenic and electrosensory system of gymnotiform fishes. These fascinating fishes produce and sense weak electric fields and use this electricity to communicate and to actively form images of the electrical properties (e.g. conductance) of the objects nearby. Some species produce these fields at a variable rate and appear to change their output in rapid response to immediate events. Other species only change their outputs in more subtle ways, over daily or seasonal periods. This has a direct impact on the performance of their electric imaging and is also a behavioral readout of specific neural circuit differences. Do species differences reflect different ecological needs or cost-benefit tradeoffs? Can we use the diversity in behaviors to examine the function of individual bits of neural circuitry?
Christopher B. Braun, PhD