The long-term objectives of this research are to describe the neural mechanisms in crayfish for the initiation of backward walking in response to abdominal illumination, and to describe the role of neural inhibiton in suppressing competing behavioral responses. This research can serve as a model for the study of normal and pathological mechanisms of behavioral initiation and coordination in humans. Intracellular microelectrode recording techniques will be used to identify and describe neurons in the crayfish brain that are excited by a pair sensory neurons, the caudal photoreceptors (CPRs) that project to the brain from the abdomen. These brain neurons provide the link between the CPR terminals in the brain and pattern initiating neurons (PIs) in the abdomen that excite the abdominal motor pattern associated with backward walking. Responses of the brain neurons to CPR input should account for the probabalistic nature of the backward walking response and the long and variable latency between CPR stimulation and the PI and motor responses. Since many non-phasic behaviors of animals are activated probabalistically with a long and variable latency following stimulation, this investigation may identify underlying neural mechanisms common to all these behaviors. The initiation of behavior requires the suppression of competing behaviors along with the selection of a preferred behavior. Behavioral evidence in crayfish and gastropod molluscs indicates that reciprocal inhibition between command systems for competing behaviors is a mechanism for this suppression. This research will investigate the inhibition of the neural circuitry for backward walking generated by the tailflip command neuron, and compare it to the inhibition of the tailflip command neuron produced by the PI neurons for backward walking. These reciprocal neural inhibitions are likely to be asymmetric in a way that reflects the asymmetry between the two behaviors: tailflip completely interrupts backward walking while backward walking merely raises the threshold for tailflip. The asymmetry of inhibition can then be seen to help establish behavioral priorities for the crayfish, such that escape tailflip is a high threshold, high priority withdrawal response, whereas backward walking is a lower threshold, easily overridden withdrawal response.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS021136-05
Application #
3401972
Study Section
Neurology B Subcommittee 1 (NEUB)
Project Start
1985-09-23
Project End
1991-08-31
Budget Start
1989-09-01
Budget End
1990-08-31
Support Year
5
Fiscal Year
1989
Total Cost
Indirect Cost
Name
Georgia State University
Department
Type
Schools of Arts and Sciences
DUNS #
837322494
City
Atlanta
State
GA
Country
United States
Zip Code
30302