In order to ultimately treat neurological disorders, we must first understand how the nervous system controls normal behavior. Among the functions that any central nervous system must control are orientation movements. These include directed movements of the animal or its limbs toward or away from specific targets. Investigation of several orientation systems have shown that the control of such movements resides in relatively large populations of interneurons. Although much can be accomplished by investigating the population as a whole, at some point one must recognize the potential of each individual neuron to contribute unique properties to the system. To address these properties, one must utilize systems in which control resides in neurons that can be identified as unique individuals from animal to animal. The cockroach escape system provides just such a system. The studies described in this proposal will attempt to ask how information on wind direction is interpreted by control interneurons in the context of ever changing external and internal environmental conditions. They take advantage of years of work that have described the basic pathway of the escape system from sensory structures and wind sensitive giant interneurons through at least two populations of control interneurons to the ultimate motor neurons and leg muscles. At each level individual neurons can be identified as individuals based upon unique morphological properties. The motor neurons responsible for specific leg movements associated with escape turns will be identified. Connections will then be identified between specific thoracic interneurons and motor neurons. The pattern of connections will indicate the form of organization that is responsible for the wind evoked turn in a static environment. Modulation will then be investigated by determining the role of additional sensory cues in modifying the turn. These will include both external cues (e.g. light and sound) and internal information on the animal's limb position at the time of stimulation. The effect of substances that are known to modulate neuronal connections will also be investigated at specific critical synapses within the pathway. Techniques that will be employed include intracellular recording and dye injection from pairs of neurons to establish specific connections between identified neurons, test of effects of neuromodulatory substances at synapses and behavioral observation of the turn utilizing a high speed video system. All of these techniques are used routinely in our laboratory. The results of these investigations will provide principles that we hope can be applied generally throughout the animal kingdom to explain how individual neurons within populations process directional information in the context of other environmental conditions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS017411-13
Application #
2263187
Study Section
Biopsychology Study Section (BPO)
Project Start
1981-09-01
Project End
1995-09-30
Budget Start
1994-04-01
Budget End
1995-09-30
Support Year
13
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Case Western Reserve University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
Ritzmann, R E; Pollack, A J (1998) Characterization of tactile-sensitive interneurons in the abdominal ganglia of the cockroach, Periplaneta americana. J Neurobiol 34:227-41
Pollack, A J; Ritzmann, R E; Watson, J T (1995) Dual pathways for tactile sensory information to thoracic interneurons in the cockroach. J Neurobiol 26:33-46
Schaefer, P L; Kondagunta, G V; Ritzmann, R E (1994) Motion analysis of escape movements evoked by tactile stimulation in the cockroach Periplaneta americana. J Exp Biol 190:287-94
Ritzmann, R E; Pollack, A J (1994) Responses of thoracic interneurons to tactile stimulation in cockroach, Periplaneta americana. J Neurobiol 25:1113-28
Nye, S W; Ritzmann, R E (1992) Motion analysis of leg joints associated with escape turns of the cockroach, Periplaneta americana. J Comp Physiol A 171:183-94
Casagrand, J L; Ritzmann, R E (1992) Evidence that synaptic transmission between giant interneurons and identified thoracic interneurons in the cockroach is cholinergic. J Neurobiol 23:627-43
Casagrand, J L; Ritzmann, R E (1992) Biogenic amines modulate synaptic transmission between identified giant interneurons and thoracic interneurons in the escape system of the cockroach. J Neurobiol 23:644-55
Ritzmann, R E; Pollack, A J; Hudson, S E et al. (1991) Convergence of multi-modal sensory signals at thoracic interneurons of the escape system of the cockroach, Periplaneta americana. Brain Res 563:175-83
Casagrand, J L; Ritzmann, R E (1991) Localization of ventral giant interneuron connections to the ventral median branch of thoracic interneurons in the cockroach. J Neurobiol 22:643-58
Ritzmann, R E; Pollack, A J (1990) Parallel motor pathways from thoracic interneurons of the ventral giant interneuron system of the cockroach, Periplaneta americana. J Neurobiol 21:1219-35

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