The research efforts of this laboratory center on documenting the organization and variation in the nervous systems of living vertebrates and utilizing these data to elucidate mechanisms underlying brain evolution. In this application, a plan is outlined for continuing studies on the organization and evolution of the vertebrate telencephalon. Living vertebrates constitute two major evolutionary radiations: jawless fishes (agnathans) and jawed vertebrates (gnathostomes), and thus far most experiments on the telencephalon have been confined to gnathostomes. Studies carried out on amphibians and lungfishes (gnathostomes) during past years of this project suggested several hypotheses regarding evolution of the vertebrate telencephalon that can be tested only by carrying out experiments on agnathans. Living agnathans--hagfishes and lampreys--exhibit extensive olfactory projections to much of the pallium. The olfacto-recipient pallium may include a dorsal pallial zone that in gnathostomes is a major site of ascending thalamic projections, or agnathans may possess an additional pallial zone that does not receive secondary olfactory input and may or may not receive thalamic input. In lampreys the dorsal thalamus may projection only to the striatum, whereas in hagfishes thalamic projections to both the striatum and portions of the pallium may exist. Analysis of the afferent and efferent connections of the pallial and dorsal thalamic areas in hagfishes and lampreys, as determined by horseradish peroxidase and tritiated amino acid tracing methods, and characterization of the distribution of various neuropeptides and biogenic amines, as revealed by immunohistochemistry, will provide the data needed to discriminate among the various hypotheses of telencephalic organization and their evolutionary implications.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS024869-07
Application #
3409827
Study Section
Neurology A Study Section (NEUA)
Project Start
1986-09-01
Project End
1994-08-31
Budget Start
1992-09-01
Budget End
1993-08-31
Support Year
7
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
Schools of Medicine
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Northcutt, R G; Wicht, H (1997) Afferent and efferent connections of the lateral and medial pallia of the silver lamprey. Brain Behav Evol 49:1-19
Webb, J F; Northcutt, R G (1997) Morphology and distribution of pit organs and canal neuromasts in non-teleost bony fishes. Brain Behav Evol 50:139-51
Amemiya, F; Northcutt, R G (1996) Afferent and efferent connections of the central prosencephalic nucleus in the Pacific hagfish. Brain Behav Evol 47:149-55
Eisthen, H L; Northcutt, R G (1996) Silver lampreys (Ichthyomyzon unicuspis) lack a gonadotropin-releasing hormone- and FMRFamide-immunoreactive terminal nerve. J Comp Neurol 370:159-72
Catania, K C (1995) Structure and innervation of the sensory organs on the snout of the star-nosed mole. J Comp Neurol 351:536-48
Catania, K C (1995) A comparison of the Eimer's organs of three North American moles: the hairy-tailed mole (Parascalops breweri), the star-nosed mole (Condylura cristata), and the eastern mole (Scalopus aquaticus). J Comp Neurol 354:150-60
Braun, C B; Wicht, H; Northcutt, R G (1995) Distribution of gonadotropin-releasing hormone immunoreactivity in the brain of the Pacific hagfish, Eptatretus stouti (Craniata: Myxinoidea). J Comp Neurol 353:464-76
Catania, K C; Kaas, J H (1995) Organization of the somatosensory cortex of the star-nosed mole. J Comp Neurol 351:549-67
Collin, S P; Northcutt, R G (1995) The visual system of the Florida garfish, Lepisosteus platyrhincus (Ginglymodi). IV. Bilateral projections and the binocular visual field. Brain Behav Evol 45:34-53
Wicht, H; Northcutt, R G (1994) An immunohistochemical study of the telencephalon and the diencephalon in a Myxinoid jawless fish, the Pacific hagfish, Eptatretus stouti. Brain Behav Evol 43:140-61

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