Michael R. Markham
Case-Hooper Associate Professor of Biology
Associate Dean, College of Arts and Sciences
Ph.D., University of New Mexico
My laboratory studies how ion channels, hormones, and behavior interact in a vertebrate communication system. We pursue this goal in a unique and powerful model organism, weakly electric fish. These fish image their world and communicate by generating electric fields in the surrounding water and detecting minute distortions of their electric fields. The electric fields are generated by the discharge of a specialized electric organ, and each electric organ discharge (EOD) is produced by the simultaneous action potentials of specialized cells within the electric organ, known as electrocytes.
Electric fish are specialists in both the modulation and precise regulation of action potential waveform, making them ideal model organisms for exploring the biochemical and biophysical control of excitable membrane physiology where real-time changes in ion channel activity have direct and immediate effects on behavior. Sex steroids organize sexual dimorphism and shape plasticity in the electrocyte action potentials, and peptide hormones regulate rapid changes in the ionic currents that shape the electrocyte action potential, producing rapid modulations of EOD waveform in in response to circadian cues and immediate social conditions. Our work focuses on investigating the cellular and ionic mechanisms of EOD generation and plasticity, the regulation of electrocyte ion currents by steroid and peptide hormones, as well as the behavioral consequences of EOD waveform modulations.