The objective of this research is to understand the neuronal basis of behaviors: how they are produced, initiated, maintained, and coordinated. To do this, we use the nervous system of the medicinal leech, because it is relatively simple and highly accessible while the animal performs many different behaviors: bending, shortening, crawling, feeding, and swimming. To be sure that we understand how these circuits work, we construct computational models that incorporate the significant features of real neurons. These models therefore, serve as a feasibility test, to make sure that we are not missing major parts of the circuit. To continue this work, we will perform the following sets of experiments: 1. We will find the neuronal basis for how one response (whole-body shortening) dominates another behavior (swimming). 2. We will determine how the crawling behavior is produced by neuronal interconnections, and how they use neurons that produce other behaviors (esp. swimming and shortening) to produce crawling. 3. We will investigate how the same interneurons can be used to produce different behaviors, and how this multiplexing of neurons affects coordination and behavioral choice. Each of the organizational features to be studies is found in all complex animals, including our own. It is important that we understand completely how these mechanisms work in any system, so that we will have a rational basis for therapeutic aids when our own brains malfunction or are injured. Using the leech, we should be able to find every neuron responsible for each of these functions and to determine how they work as a unit to produce normal behavior.

National Institute of Health (NIH)
National Institute of Mental Health (NIMH)
Research Project (R01)
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Cognitive Functional Neuroscience Review Committee (CFN)
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Glanzman, Dennis L
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University of California San Diego
Schools of Arts and Sciences
La Jolla
United States
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Pipkin, Jason E; Bushong, Eric A; Ellisman, Mark H et al. (2016) Patterns and distribution of presynaptic and postsynaptic elements within serial electron microscopic reconstructions of neuronal arbors from the medicinal leech Hirudo verbana. J Comp Neurol 524:3677-3695
Woodford, Clifford R; Frady, E Paxon; Smith, Richard S et al. (2015) Improved PeT molecules for optically sensing voltage in neurons. J Am Chem Soc 137:1817-24
Palmer, Chris R; Barnett, Megan N; Copado, Saul et al. (2014) Multiplexed modulation of behavioral choice. J Exp Biol 217:2963-73
Gaudry, Quentin; Kristan Jr, William B (2012) Decision points: the factors influencing the decision to feed in the medicinal leech. Front Neurosci 6:101
Miller, Evan W; Lin, John Y; Frady, E Paxon et al. (2012) Optically monitoring voltage in neurons by photo-induced electron transfer through molecular wires. Proc Natl Acad Sci U S A 109:2114-9
Palmer, Chris R; Kristan Jr, William B (2011) Contextual modulation of behavioral choice. Curr Opin Neurobiol 21:520-6
Todd, Krista L; Kristan Jr, William B; French, Kathleen A (2010) Gap junction expression is required for normal chemical synapse formation. J Neurosci 30:15277-85
Baltzley, Michael J; Gaudry, Quentin; Kristan Jr, William B (2010) Species-specific behavioral patterns correlate with differences in synaptic connections between homologous mechanosensory neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 196:181-97
Gaudry, Q; Ruiz, N; Huang, T et al. (2010) Behavioral choice across leech species: chacun a son gout. J Exp Biol 213:1356-65
Wagenaar, Daniel A; Gonzalez, Ruben; Ries, David C et al. (2010) Alpha-conotoxin ImI disrupts central control of swimming in the medicinal leech. Neurosci Lett 485:151-6

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