1) Permanent ectopic retinal projections to auditory or somatosensory thalamic nuclei can be reliably produced by neurosurgery on newborn Syrian hamsters. Neurophysiological recording and the 2-deoxyglucose metabolic mapping techniques will be used to determine if the anomalous projections drive thalamic neurons or the cortical neurons to which the thalamic neurons project. The receptive field properties of single neurons receiving the anomalous visual input and the retinotopic organization of the ectopic visual pathways will also be studied electrophysiologically. The development of the ectopic projections will be studied by anterograde transport techniques. The results of these studies have fundamental implications for the development of orderly connections and single unit receptive field properties in normal animals and are of potential value in the treatment of central nervous system (CNS) lesions in man. 2) The optic tract and second order somatosensory pathways regrow following transection in neonatal hamsters. Retrograde transport of enzymatic and fluorescent tracers will be used to determine whether this regrowth is due to regeneration of cut axons or to the growth of late-developing uncut axons, across the level of transection. The time course of the regrowth will also be examined. These studies will help to determine the circumstances under which transected CNS axons can regenerate; this is important for the clinical treatment of traumatic injury of the CNS.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY003465-11
Application #
2158810
Study Section
Visual Sciences B Study Section (VISB)
Project Start
1988-09-30
Project End
1993-03-31
Budget Start
1990-04-01
Budget End
1993-03-31
Support Year
11
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Rodger, Jennifer; Frost, Douglas O (2009) Effects of trkB knockout on topography and ocular segregation of uncrossed retinal projections. Exp Brain Res 195:35-44
Bhide, P G; Frost, D O (1999) Intrinsic determinants of retinal axon collateralization and arborization patterns. J Comp Neurol 411:119-29
Metin, C; Irons, W A; Frost, D O (1995) Retinal ganglion cells in normal hamsters and hamsters with novel retinal projections. I. Number, distribution, and size. J Comp Neurol 353:179-99
Boire, D; Morris, R; Ptito, M et al. (1995) Effects of neonatal splitting of the optic chiasm on the development of feline visual callosal connections. Exp Brain Res 104:275-86
Bhide, P G; West, W C; Fry, K R et al. (1994) An immunocytochemical marker for hamster retinal ganglion cells. J Neurocytol 23:167-77
Kadhim, H J; Bhide, P G; Frost, D O (1993) Transient axonal branching in the developing corpus callosum. Cereb Cortex 3:551-66
Bhide, P G; Frost, D O (1992) Axon substitution in the reorganization of developing neural connections. Proc Natl Acad Sci U S A 89:11847-51
Bhide, P G; Frost, D O (1991) Stages of growth of hamster retinofugal axons: implications for developing axonal pathways with multiple targets. J Neurosci 11:485-504
Langdon, R B; Frost, D O (1991) Transient retinal axon collaterals to visual and somatosensory thalamus in neonatal hamsters. J Comp Neurol 310:200-14
Frost, D O (1990) Sensory processing by novel, experimentally induced cross-modal circuits. Ann N Y Acad Sci 608:92-109;discussion 109-12

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