All nervous systems employ a large umber of amines, amino acids and neuropeptides as neurotransmitters and neuromodulators. Despite years of work on individual brain signaling systems, the organizational principles underlying neuromodulation remain incompletely understood. The proposed work will employ the crustacean stomatogastric nervous system to address a series of general questions about neuromodulation of brain circuits. Mass spectrometry will be used to determine the identity of neuropeptides in specific sensory and modulatory neurons. The function of the specific neuropeptides found in identified neurons will be examined electrophysiologically. In cases in which multiple members of a peptide family are found in the same identified neurons, the potency and action of the different family members will be compared. To determine how a single neuron organizes receptors for 12 or 15 different neurotransmitters or modulators, neurons will be filled with fluorescent dye, and agonists applied to various regions of the neuron to localize its receptors. Further experiments will characterize the voltage-dependence and pharmacological profile of the evoked responses. The effects of neuromodulators on circuit reorganization will be studied with quantitative methods that determine how different frequency rhythms interact. Additionally, the effects of neuromodulators on signal propagation will be investigated by determining the extent to which externally imposed signals (sine waves of various frequencies) influence the activity of circuit neurons. Together these data will contribute to basic understandings of how different neuromodulatory systems can modify networks to produce behaviorally relevant changes in function.

Public Health Relevance

Amines and neuropeptides are key to the function of the nervous system, and are important in controlling mood, attention, and changes in behavioral state in sleep, feeding, and locomotion. Despite their widespread importance, relatively little is known about the overall organization of neuromodulatory systems in behavior. The proposed work will reveal general principles relevant to neuromodulatory action.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Method to Extend Research in Time (MERIT) Award (R37)
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Special Emphasis Panel (ZRG1-IFCN-E (03))
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Liu, Yuan
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Brandeis University
Schools of Arts and Sciences
United States
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Rosenbaum, Philipp; Marder, Eve (2018) Graded Transmission without Action Potentials Sustains Rhythmic Activity in Some But Not All Modulators That Activate the Same Current. J Neurosci 38:8976-8988
Otopalik, Adriane G; Sutton, Alexander C; Banghart, Matthew et al. (2017) When complex neuronal structures may not matter. Elife 6:
Nusbaum, Michael P; Blitz, Dawn M; Marder, Eve (2017) Functional consequences of neuropeptide and small-molecule co-transmission. Nat Rev Neurosci 18:389-403
Otopalik, Adriane G; Goeritz, Marie L; Sutton, Alexander C et al. (2017) Sloppy morphological tuning in identified neurons of the crustacean stomatogastric ganglion. Elife 6:
Gjorgjieva, Julijana; Drion, Guillaume; Marder, Eve (2016) Computational implications of biophysical diversity and multiple timescales in neurons and synapses for circuit performance. Curr Opin Neurobiol 37:44-52
Marder, Eve (2015) Understanding brains: details, intuition, and big data. PLoS Biol 13:e1002147
Marder, Eve; Goeritz, Marie L; Otopalik, Adriane G (2015) Robust circuit rhythms in small circuits arise from variable circuit components and mechanisms. Curr Opin Neurobiol 31:156-63
Gutierrez, Gabrielle J; Marder, Eve (2014) Modulation of a Single Neuron Has State-Dependent Actions on Circuit Dynamics(,.) eNeuro 1:
Shruti, Sonal; Schulz, David J; Lett, Kawasi M et al. (2014) Electrical coupling and innexin expression in the stomatogastric ganglion of the crab Cancer borealis. J Neurophysiol 112:2946-58
Hamood, Albert W; Marder, Eve (2014) Animal-to-Animal Variability in Neuromodulation and Circuit Function. Cold Spring Harb Symp Quant Biol 79:21-8

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