We propose experiments to examine the anatomical substrate and physiological consequences of a dramatic rerouting of retinal projections to the auditory thalamus and cortex in ferrets. The organization of the visual pathway in normal ferrets in very similar to that in cats. We have successfully induced, with appropriate surgery in neonatal ferrets, retinal projections into the medial geniculate nucleus (MGN), the principal auditory thalamic nucleus. The MGN with retinal input retains its projections to auditory cortex. We now propose to study visual responses from, and the extrinsic and intrinsic connectivity of, the MGN and primary auditory cortex in operated ferrets reared to adulthood. Specific electrophysiological experiments include mapping the projection of the visual field onto the MGN and primary auditory cortex, studying the types of retinal input and receptive fields of visual cells in the MGN, and the receptive field properties of visual cells in primary auditory cortex. Anatomical experiments include defining in detail the projection of the two eyes to the auditory thalamus and cortex, the cells of origin of retinal projections to the MGN, and the subcortical and cortical connectivity of auditory thalamus and cortex in operated animals. We shall initiate ultrastructural studies of the synaptic organization of MGN cells with retinal input. We shall compare these features with corresponding features of the lateral geniculate nucleus (LGN) and primary visual cortex, or the MGN and primary auditory cortex, of normal animals. The overall goal of our experiments is thus to address a fundamental issue in development: whether structure and function in a target is determined by intrinsic properties of the target, or by its inputs during development.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
3R01EY007719-03S1
Application #
3264741
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1988-07-01
Project End
1992-03-31
Budget Start
1990-07-01
Budget End
1992-03-31
Support Year
3
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Type
Other Domestic Higher Education
DUNS #
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Ladd, W M; Lindstrom, M J (2000) Self-modeling for two-dimensional response curves. Biometrics 56:89-97
Angelucci, A; Clasca, F; Sur, M (1998) Brainstem inputs to the ferret medial geniculate nucleus and the effect of early deafferentation on novel retinal projections to the auditory thalamus. J Comp Neurol 400:417-39
Angelucci, A; Clasca, F; Sur, M (1996) Anterograde axonal tracing with the subunit B of cholera toxin: a highly sensitive immunohistochemical protocol for revealing fine axonal morphology in adult and neonatal brains. J Neurosci Methods 65:101-12
Pallas, S L; Hahm, J; Sur, M (1994) Morphology of retinal axons induced to arborize in a novel target, the medial geniculate nucleus. I. Comparison with arbors in normal targets. J Comp Neurol 349:343-62
Pallas, S L; Sur, M (1994) Morphology of retinal axon arbors induced to arborize in a novel target, the medial geniculate nucleus. II. Comparison with axons from the inferior colliculus. J Comp Neurol 349:363-76
Sur, M (1993) Cortical specification: microcircuits, perceptual identity, and an overall perspective. Perspect Dev Neurobiol 1:109-13
Roe, A W; Garraghty, P E; Esguerra, M et al. (1993) Experimentally induced visual projections to the auditory thalamus in ferrets: evidence for a W cell pathway. J Comp Neurol 334:263-80
Pallas, S L; Sur, M (1993) Visual projections induced into the auditory pathway of ferrets: II. Corticocortical connections of primary auditory cortex. J Comp Neurol 337:317-33
Roe, A W; Pallas, S L; Kwon, Y H et al. (1992) Visual projections routed to the auditory pathway in ferrets: receptive fields of visual neurons in primary auditory cortex. J Neurosci 12:3651-64
Pallas, S L; Roe, A W; Sur, M (1990) Visual projections induced into the auditory pathway of ferrets. I. Novel inputs to primary auditory cortex (AI) from the LP/pulvinar complex and the topography of the MGN-AI projection. J Comp Neurol 298:50-68

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