Almost all animals, including humans, produce rhythmic behavior. Studying the modulation and neural control of motor rhythms is important for several reasons. Such studies provide insight into the mechanisms by which organisms match motor outputs to their environment and also increase our understanding of disorders that disrupt the nervous system's ability to smoothly and spontaneously produce motor rhythms. Studies of central pattern generators (CPGs), networks of neurons that produce the timing signals for rhythmic behavior, have elucidated mechanisms of motor control at both systems and cellular levels. CPGs in vertebrate animals are often complex. Although in vitro preparations have allowed researchers to study mechanisms of pattern generation in vertebrate systems, identifying all of the component neurons and relating their intrinsic properties and connectivity to motor output is a challenging and active area of research. ? ? The proposed research will examine the cellular mechanisms of pattern generation in the electromotor system in weakly electric fish. This system controls the timing of electric organ discharges (EODs), which function in electrolocation and communication. The electromotor system is well suited for studying the neural mechanisms of motor rhythms for several reasons. First, the electromotor system contains only 3-4 different neuron types and is therefore a simpler neural circuit than most other vertebrate CPGs. Secondly, there is a straightforward relationship between the in vitro firing patterns of these neurons and the in vivo output of the circuit (the EOD), which allows us to relate observations at the cellular level to behavior. Finally, hormonally-induced sex differences and individual variation in EOD frequency are preserved in the firing patterns of neurons in reduced (in vitro) preparations. This feature will provide a rare opportunity to study the cellular mechanisms underlying sexual dimorphism and individual variation in rhythmic behavior. ? ? We will use intracellular current clamp recordings, pharmacological manipulations, and whole-cell voltage clamp to characterize ionic currents in electromotor neurons (EMNs), one of two spontaneously oscillating cell types in the electromotor circuit. These studies will allow us to generate a model that explains the spontaneous rhythmicity of EMNs. We will also examine the relationship between the biophysical properties of ionic currents in EMNs and individual variation in EOD frequency, which will allow us to examine how changes in neuronal excitability influence individual variation and sex differences in rhythmic behavior.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH066960-02
Application #
6697135
Study Section
Integrative, Functional and Cognitive Neuroscience 8 (IFCN)
Program Officer
Glanzman, Dennis L
Project Start
2003-01-15
Project End
2007-12-31
Budget Start
2004-01-01
Budget End
2004-12-31
Support Year
2
Fiscal Year
2004
Total Cost
$219,300
Indirect Cost
Name
Indiana University Bloomington
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
006046700
City
Bloomington
State
IN
Country
United States
Zip Code
47401
Allen, Antino R; Smith, G Troy (2012) Spinal transection induces widespread proliferation of cells along the length of the spinal cord in a weakly electric fish. Brain Behav Evol 80:269-80
Ho, Winnie W; Fernandes, Cristina Cox; Alves-Gomes, José A et al. (2010) Sex differences in the electrocommunication signals of the electric fish Apteronotus bonapartii. Ethology 116:1050-1064
Smith, G Troy; Combs, Nicole (2008) Serotonergic activation of 5HT1A and 5HT2 receptors modulates sexually dimorphic communication signals in the weakly electric fish Apteronotus leptorhynchus. Horm Behav 54:69-82
Stevens, Jack; Kelleher, Kelly; Greenhouse, Joel et al. (2007) Empirical evaluation of the generalizability of the sample from the multimodal treatment study for ADHD. Adm Policy Ment Health 34:221-32
Kolodziejski, Johanna A; Sanford, Sara E; Smith, G Troy (2007) Stimulus frequency differentially affects chirping in two species of weakly electric fish: implications for the evolution of signal structure and function. J Exp Biol 210:2501-9
Zhou, Muchu; Smith, G Troy (2006) Structure and sexual dimorphism of the electrocommunication signals of the weakly electric fish, Adontosternarchus devenanzii. J Exp Biol 209:4809-18
Smith, G Troy (2006) Pharmacological characterization of ionic currents that regulate high-frequency spontaneous activity of electromotor neurons in the weakly electric fish, Apteronotus leptorhynchus. J Neurobiol 66:1-18
Smith, G Troy; Unguez, Graciela A; Weber, Christopher M (2006) Distribution of Kv1-like potassium channels in the electromotor and electrosensory systems of the weakly electric fish Apteronotus leptorhynchus. J Neurobiol 66:1011-31
Smith, G Troy; Allen, Antino R; Oestreich, Jorg et al. (2005) L-citrulline immunoreactivity reveals nitric oxide production in the electromotor and electrosensory systems of the weakly electric fish, Apteronotus leptorhynchus. Brain Behav Evol 65:1-13
Greenhouse, Joel B; Kelleher, Kelly J (2005) Thinking outside the (black) box: antidepressants, suicidality, and research synthesis. Pediatrics 116:231-3

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