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Sequential recovery of sensitivity to negative and positive contrasts during optic nerve regeneration in goldfish

Published online by Cambridge University Press:  04 May 2001

D.P.M. NORTHMORE
Affiliation:
Departments of Psychology and Biology, University of Delaware, Newark
D.-J. OH
Affiliation:
Departments of Psychology and Biology, University of Delaware, Newark

Abstract

A psychophysical procedure, classical conditioning of respiration, was used to measure contrast sensitivity to positive- and negative-contrast discs (8-deg diameter) in goldfish after crushing one optic nerve intraorbitally. In five out of six fish, sensitivity recovered to normal. Recovery times for negative contrasts were significantly shorter than for positive contrasts. The average times postcrush of initial responding to negative and positive contrasts were 23.8 and 30.6 days, and for threshold to come within 0.5 log unit of control values was 29.8 and 39.8 days, respectively. Thereafter, recovery to normal sensitivity was significantly faster for positive contrasts. These results parallel prior observations of neural activity in tectum after optic nerve crush: an early phase of OFF responding followed by a more sudden recovery of ON responding.

Type
Research Article
Copyright
2001 Cambridge University Press

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