Recovery of visual evoked potentials after regeneration of cut retinal ganglion cell axons within the ascending visual pathway in adult rats.
OBJECTIVE
Following optic nerve damage, retinal ganglion cells (RGCs) fail to regenerate their axons and soon undergo apoptosis. However, many RGCs survive axotomy and regenerate lengthy axons after a lens injury (LI). If the cut optic nerve is re-sutured, RGC axons grow into the distal part of the optic nerve and reach their natural targets within the thalamus and midbrain. In this study, we check time-dependence and extent of restoration of flash visual evoked potentials (FVEPs) to examine the functional relevance of the regenerated retinogeniculate pathway.


METHODS
The optic nerve in adult rats was cut and re-sutured. The lens was injured transsclerally using a pointed glass capillary. FVEPs were measured starting at the time point of surgery, and then repeatedly up to an age of several months.


RESULTS
Detectable FVEPs appeared approximately ten weeks after the surgery, and their amplitudes increased during the next months to reach eventually 15-40% of their values before surgery.


CONCLUSIONS
Partial restoration of FVEPs indicates that some regenerating RGC axons have "bridged" the distance between the eye and the central targets forming a functional re-connection of the corresponding RGC with thalamic target neurones to elicit recordable activation of the visual cortex.
Department of Experimental Ophthalmology, University Eye Hospital Münster, Domagkstr. 15, D - 48149 Münster, Germany. peter.heiduschka@novartis.com
Peter
P
Heiduschka
Dietmar
D
Fischer
Solon
S
Thanos
D000818:Animals; D004195:Disease Models, Animal; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D008297:Male; D009416:Nerve Regeneration / Q000502:physiology*; D020221:Optic Nerve Injuries / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000473:pathology / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology; D014795:Visual Pathways / Q000503:physiopathology*