Morphological changes in the neuronal substrate for the optokinetic reflex in albino ferrets
I. Telkes & K.-P. Hoffmann
Exp. Brain Res., 140, 345-356, 2001
- Albino mammals show very characteristic deficits in their optokinetic
system, and albino ferrets are even optokinetically blind. To investigate the neuronal causes for this defect we
compared the morphology of retinal slip cells in the pretectal nucleus of the optic tract and the dorsal terminal
nucleus of the accessory optic system (NOT-DTN) in pigmented and albino ferrets (Mustela putorius furo) using retrograde
tracing techniques. After tracer injections into the inferior olive, equal numbers of NOT-DTN neurons were retrogradely
labelled in pigmented and albino animals. However, NOT-DTN cells in albino ferrets had fewer stem dendrites, and
the cumulative dendritic length was reduced by 30% when compared with NOT-DTN neurons in pigmented animals. In
addition, the prominent network formed by distal dendrites observed in the NOT-DTN of pigmented ferrets was largely
diminished in albinos. Taken together with behavioural and physiological data, these findings indicate that the
NOT-DTN as the main visuomotor interface in the optokinetic system is clearly defective in albino ferrets.
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