Information Processing

in Mammalian Auditory Cortex


Sensory information is represented by the distributed activity of large numbers of neurons in a number of distinct brain regions. To better characterize how acoustic features are processed by the central auditory system, we record how individual neurons and populations of neurons respond to sounds ranging from simple clicks and tones to complex stimuli including animal vocalizations and human speech. Microelectrode mapping studies allow us to record from up to 160 sites in a single animal. This approach allows the highest density sampling of neurons possible today, but necessitates recordings be made from anesthetized animals. We have also developed techniques to record from 16 electrodes at once from awake, freely moving animals using chronically implanted microwire arrays. Since most recording of neural activity in humans take the form of far-field evoked potentials, we also study similar potentials in awake rats by recording from epidural EEG electrodes.

To date, we have characterized in detail the responses of rat auditory thalamus, primary auditory cortex, posterior auditory field, and ventral auditory field to tone and noise burst trains, FM sweeps, spectral gratings, spectrotemporal sequences, maromoset vocalizations, and human speech. These studies provide considerable insight into the processing of sensory information. These studies also provide baseline data for plasticity studies designed to explore how these responses are altered by different forms of sensory experience.


        Awake Multi-Channel Recordings

        Anesthetized Microelectrode Mapping

        Auditory Evoked Potentials

        Speech Processing