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Dark-rearing fails to affect the basal dendritic fields of layer 3 pyramidal cells in the kitten's visual cortex
S B Tieman1, N Zec, D G Tieman
1Neurobiology Research Center, State University of New York, Albany 12222, USA.
Insights
Early visual experience shapes the cat
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Visual System Research
Background:
- The cat's visual cortex matures postnatally, influenced by early visual input.
- Previous research showed basal dendritic fields of layer 3 pyramidal cells grow significantly in the first 5 weeks.
- Stripe-rearing alters the orientation of these dendritic fields.
Purpose of the Study:
- To investigate the impact of visual deprivation (dark-rearing) on the dendritic fields of layer 3 pyramidal cells in the cat's visual cortex.
- To compare dendritic field parameters between normally reared and dark-reared cats.
Main Methods:
- Golgi impregnation of visual cortices from normally reared and dark-reared cats.
- Tangential sectioning and counterstaining of cortical tissue.
- Camera lucida tracing and quantitative analysis of basal dendritic fields of layer 3 pyramidal cells.
Main Results:
- No significant differences were found in the number or length of primary dendrites, branching, size, elongation, or orientation distribution of dendritic fields between groups.
- Dark-rearing during the first 3 months did not alter the measured parameters of layer 3 pyramidal cell dendritic fields.
Conclusions:
- Visual deprivation through dark-rearing does not affect the basal dendritic fields of layer 3 pyramidal cells in cats.
- This contrasts with findings on stripe-rearing's effect on orientation and other studies showing dark-rearing impacts layer 4 stellate cells.
Abstract:
The development of the cat's visual cortex is incomplete at birth and is influenced by the cat's early visual experience. We have previously demonstrated that the basal dendritic fields of layer 3 pyramidal cells grow substantially during the first 5 weeks after birth and that stripe-rearing affects their orientation. In this paper we determined the effects on these dendritic fields of visual deprivation (dark-rearing) during the first 3 months of life. The visual cortices of both normally reared and dark-reared cats were impregnated by the Golgi method, sectioned in the tangential plane and counterstained. The basal dendritic fields of completely impregnated pyramidal cells from layer 3 were drawn with the aid of a camera lucida, and compared in terms of number and length of primary dendrites, branching, size, elongation, and distribution of dendritic field orientations. Surprisingly, we observed no significant differences in any parameter measured. Thus, although stripe-rearing can specifically alter the orientation of the dendritic fields of the layer 3 pyramidal cells, and dark-rearing has been shown by others to alter the size of layer 4 stellate cells, dark-rearing failed to affect the dendritic fields of layer 3 pyramidal cells.