Effect of longer periods of dark rearing on NMDA receptors in cat visual cortex.
1. Cats were reared in the dark to 3, 5, and 11 mo. We studied the N-methyl-D-aspartate (NMDA) receptor contribution to the visual response in the cortex, defined as the percentage reduction in visual response after application of 2-amino-5-phosphonovaleric acid (APV). We also studied the firing rate in response to the optimal visual stimulus and the spontaneous activity. We made comparisons of all these properties between light-reared and dark-reared animals. 2. The NMDA receptor contribution to the visual response in layers IV, V, and VI of dark-reared animals was substantially above that in light-reared animals at all ages tested. 3. The specificity of receptive field properties in dark-reared animals showed some degeneration between 6 wk and 3 mo of age. At > or = 3 mo, almost no cells were specific for orientation and direction of movement. 4. Firing rate was lower in dark-reared animals at all ages, suggesting a decrease in excitatory drive to the visual cortex. 5. Spontaneous activity was equal in dark- and light-reared animals, suggesting that the overall level of activity (including visual responses as well as spontaneous activity) in light-reared animals is higher than in dark-reared animals. This should tend to upregulate glutamate receptors in general in dark-reared animals.
Czepita
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Department of Ophthalmology and Visual Science, Yale University Medical School, New Haven, Connecticut 06520-8061.
Reid
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Daw
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D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D002415:Cats; D003623:Dark Adaptation / Q000187:drug effects / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009949:Orientation / Q000187:drug effects / Q000502:physiology; D010775:Photic Stimulation; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology*; D014793:Visual Cortex / Q000187:drug effects / Q000502:physiology*; D014796:Visual Perception / Q000187:drug effects / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate