| Co-Investigator(Kenkyū-buntansha) |
ISHII Sawako Assistant of Anatomy, Kumamoto University, Medical School, 医学部, 助手 (60040169)
FUKUSHIMA Natsuko Assistant of Anatomy, Kumamoto University, Medical School, 医学部, 助手 (50040168)
HIGO Shigeyoshi Assistant of Anatomy, Kumamoto University, Medical School, 医学部, 助手 (50165099)
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| Budget Amount *help |
¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1987: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1986: ¥3,500,000 (Direct Cost: ¥3,500,000)
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| Research Abstract |
The purpose of this project is to clarify the difference of cortical inputs ( areal and laminar termination in the visual cortex ) according to their subcortical origins by means of several neuroanatomical tecniques. In order to achieve the above main objective, we specifically took the following strategies: 1) to identify the subcortical origins by injecting retrograde tracers into the visual cortex, 2) to examine the cortical extent of termination by injections of orthograde tracers into the subcortical structures identified in 1), and 3) to analyze the differences of extent of terminals according to specific layers in the cortex that arise from the same subcortical origins.
The visual cortex receives inputs from various subcortical structures, not only from the diencephalic and telencephalic, but also from the mesencephalic structures; in the telencephalon, the origins of the inputs were identified in the claustrum, the basal nucleus of Meynert and the diagonal band of Broca; in the
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diencehalon, they were found in part of the hypothalamus and the dorsal thalamic nuclei, such as the dorsal lateral geniculate nucleus ( LGNd ), the pulvinar ( Pul ) the nucleus lateralis posterior (Lp), and the intralaminar nuclei; and in the mesencephalon, they exist in the ventral tegmental field and part of the raphe nucleus. In the next stage, we examined the cortical extent of terminals arising from the above mentioned structures. These results showed that the fibers terminate in different cortical layers according to a specific origin. (1) Fibers from the LGNd ( A and A1 ) terminate in the intermediate portions of layers IV and VI of areas 17 and 18; those from the magnocellular C lamina, in the superficial and deep parts of layers IV and VI; and those from the parvicellular C laminae terminate in layers V, the deep part of layer III, and in layer I. The cortical extent of these terminations also differs according to the origins; terminals in layer I extend most widely beyond the limit of the visual cortex. (2) Fibers from the Lp terminate in area 17 similar to those from the parvicellular C laminae. (3) Fibers from the other subcortical origins such as the intralaminar nuclei and the midbrain structures terminate in layer I, particularly those origins such as the intralaminar nuclei and the midbrain structures terminate in layer I, particularly those from the midbrain structres are distributed over layer I. From these results, it is concluded that a given cortical area receives inputs in different layers from various cortical structures, and the terminal extent of each layer is also different according to the origin. Less
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