| Co-Investigator(Kenkyū-buntansha) |
MATSUSHIMA Toshiya FACULTY OF SCIENCE, UNIVERSITY OF TOKYO INSTRUCTOR, 理学部, 助手 (40190459)
OKA Yoshitaka FACULTY OF SCIENCE, UNIVERSITY OF TOKYO INSTRUCTOR, 理学部, 助手 (70143360)
SATOU Masahiko FACULTY OF SCIENCE, UNIVERSITY OF TOKYO ASSOCIATE PROFESSOR, 理学部, 助教授 (50124673)
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| Budget Amount *help |
¥11,300,000 (Direct Cost: ¥11,300,000)
Fiscal Year 1987: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1986: ¥8,700,000 (Direct Cost: ¥8,700,000)
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| Research Abstract |
FISH SEXUAL BEHAVIOR IS AN EXCELLENT SUBJECT FOR THE STUDY OF THE NEURAL BASIS UNDERLYING THE INSTINCTIVE BEHAVIOR, BECAUSE IT IS COMPOSED OF DISTINCT FIXED ACTION PATTERNS, EACH OF WHICH IS CLEARLY RELATED TO RESPECTIVE KEY STIMULUS. WE MADE A SERIES OF NEUROETHOLOGICAL STUDIES MAINLY IN SALMONID FISH TO SOLVE PRINCIPAL PROBLEMS SUCH AS THE MOTOR PATTERN GENERATOR, THE INNATE RELFASING MECHANISM, AND THE MECHANISM FOR HIERARCHICAL CONTROL.
1. MOTOR PATTERN GENERATOR FOR SEXUAL BEHAVIOR THE SEXUAL BEHAVIOR OF SALMON CONSISTS OF A SERIES OF FIXED ACTION PATTERNS, I.E., NEST-BUILDING BY THE FEMALE, COURTING BY THE MALE, AND SPAWNING BY BOTH SEXES. TO PRECISELY CHARACTERIZE THE MOTOR PATTERNS OF THESE BEHAVIOR, WE ANALYZED ELECTROMYOGRAPHIC ACTIVITIES ACCOMPANYING THESE ACTION PATTERNS. AS THE RESULT, MALES' COURTING AND SPAWNING AS WELL AS FEMALES' NEST-BUILDING PROVED TO BE ACCOMPANIED WITH RHYTHMIC ACTIVITIES OF TRUNK MUSCULATURES, SUGGESTING THE INVOLVEMENT OF THE SPINAL SWIMMING PATTE
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RN GENERATOR IN THESE BEHAVIOR PATTERNS. NEXT, WE NEUROANATOMICALLY EXAMINED THE DESCENDING PATHWAYS TO THE SPINAL CORD. SEVERAL MESENCEPHALIC AND RHOMENCEPHALIC REGIONS WERE FOUND TO SEND DESCENDING AXONS TO THE SPINAL CORD: THEY ARE NUC. OF PRETECTALIS, NUC. OF FASCICULI LONGITUDINALIS MEDIALIS, NUC. OF RUBER, BULBAR RETICULAR FORMATION, AND OTHERS. SOME OF THESE AREAS MAY BE RESPONSIBLE FOR COMMANDS OF SEXUAL BEHAVIOR.
2. INNATE RELEASING MECHANISMS FOR SEXUAL BEHAVIOR TO QUANTITATIVELY SURVEY THE KEY STIMULI FOR ELICITING MALE SEXUAL BEHAVIOR, WE MADE A SERIES OF MODEL PRESENTATION EXPERIMENTS. IT WAS FOUND THAT CHARACTERISTIC VISUAL CUES [HORIZONTALLY ELONGATED RECTANGLE (BLACK ABOVE AND WHITE BELOW) AND MOVEMENT WHICH SIMULATES FEMALE SEXUAL BEHAVIOR] PLAY AN ESSENTIAL ROLE FOR ELICITING THE COURTING BEHAVIOR; ON THE OTHER HAND, VIBRATIONAL SIGNALS AS WELL AS VISUAL CUES ARE INVOLVED FOR ELICITING THE SPAWNING BEHAVIOR. THE VISUAL CUES GUIDE THE MALE TO THE FEMALF, WHILE THE VIBRATIONAL CUES TRIGGER THE MALE TO SPAWN.
3. HIERARCHICAL CONTROL OF SEXUAL BEHAVIOR. ELECTRICAL BRAIN STIMULATION AND LESION STUDIES REVEALED THAT VENTRAL TELENCEPHALON AND THE MEDIAL PREOPTIC AREA HIERARCHICALLY CONTROL THE SEXUAL BEHAVIOR. CYTOARCHITECTURES OF THESE AREAS WERE EXAMINED BY RAPID GOLGI METHODS. FURTHEMORE, IMMUNOCYTOCHEMICAL STUDIES IN THE DWARF GOURAMI HAVE SHOWN ABUNDANT LH-RH IMMUNOREACTIVE FIBERS RUNNING THROUGH THESE SEXUAL-BEHAVIOR RELEVANT AREAS, SUGGESTING THE POSSIBLE INVOLVEMENT OF LH-RH SYSTEMS AND TERMINAL NERVE SYSTEMS IN FISH SEXUAL BEHAVIOR. Less
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