Change in the activity of excitable membranes is a cornerstone of functional modification within the vertebrate nervous system. Modification of nervous system activity, in turn, is a cornerstone of behavioral change in vertebrates. Thus, understanding the regulation of excitable membranes contributes to our understanding of nervous system function and relating these changes to in vivo behavioral changes presents a powerful approach to an integrated understanding of behavior change and its biological bases. An ideal model for such research is the weakly electric fish, B. pinnicaudatus, which generates electric fields, known as electric organ discharges (EODs), for electrolocation and communication. The amplitude and duration of the EOD waveform varies in response to environmental variables apparently controlled by steroid effects. Because the EOD results from synchronized ionic membrane currents of all electrocytes within the electric organ, changes in EOD waveform reflect changes in ion currents of individual electrocytes. By determining the cellular and molecular mechanisms of EOD waveform change it is possible to determine a chain of continuous causal connections relating environmentally controlled behavior to its neural, endocrine, and cellular causes. The project proposed here will apply electrophysiological techniques including single unit recording, two-electrode voltage clamp, and patch-clamp recording to discover the physiological mechanisms by which B. pinnicaudatus regulate these changes inEOD. The project's specific aims are to 1) relate the phases of the EOD to its corresponding extracellular potentials and intracellular action potentials 2) determine which ion currents contribute to the two phases of the extracellular potential and to the intracellular action potential 3) determine the mechanisms by which rapid changes in EOD waveform are expressed in the extracellular potentials and intracellular potentials and intracellular potentials of individual electrocytes, and 4) determine how specific ion currents change when the EOD changes in amplitude and duration.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Scientist Development Award - Research & Training (K01)
Project #
5K01MH064550-03
Application #
6834586
Study Section
Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
Program Officer
Desmond, Nancy L
Project Start
2003-01-01
Project End
2007-12-31
Budget Start
2005-01-01
Budget End
2005-12-31
Support Year
3
Fiscal Year
2005
Total Cost
$133,375
Indirect Cost
Name
Florida International University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
071298814
City
Miami
State
FL
Country
United States
Zip Code
33199
Markham, Michael R; Stoddard, Philip K (2013) Cellular mechanisms of developmental and sex differences in the rapid hormonal modulation of a social communication signal. Horm Behav 63:586-97
Markham, Michael R; McAnelly, M Lynne; Stoddard, Philip K et al. (2009) Circadian and social cues regulate ion channel trafficking. PLoS Biol 7:e1000203
Markham, Michael R; Allee, Susan J; Goldina, Anna et al. (2009) Melanocortins regulate the electric waveforms of gymnotiform electric fish. Horm Behav 55:306-13
Allee, Susan J; Markham, Michael R; Stoddard, Philip K (2009) Androgens enhance plasticity of an electric communication signal in female knifefish, Brachyhypopomus pinnicaudatus. Horm Behav 56:264-73
Allee, Susan J; Markham, Michael R; Salazar, Vielka L et al. (2008) Opposing actions of 5HT1A and 5HT2-like serotonin receptors on modulations of the electric signal waveform in the electric fish Brachyhypopomus pinnicaudatus. Horm Behav 53:481-8
Stoddard, Philip K; Markham, Michael R (2008) Signal Cloaking by Electric Fish. Bioscience 58:415-425
Stoddard, Philip K; Markham, Michael R; Salazar, Vielka L et al. (2007) Circadian rhythms in electric waveform structure and rate in the electric fish Brachyhypopomus pinnicaudatus. Physiol Behav 90:11-20
Stoddard, Philip K; Zakon, Harold H; Markham, Michael R et al. (2006) Regulation and modulation of electric waveforms in gymnotiform electric fish. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 192:613-24
Markham, Michael R; Stoddard, Philip K (2005) Adrenocorticotropic hormone enhances the masculinity of an electric communication signal by modulating the waveform and timing of action potentials within individual cells. J Neurosci 25:8746-54
Stoddard, Philip K; Markham, Michael R; Salazar, Vielka L (2003) Serotonin modulates the electric waveform of the gymnotiform electric fish Brachyhypopomus pinnicaudatus. J Exp Biol 206:1353-62