Abstract
Fish retinal ganglion cells can survive and regrow their axons after optic nerve transection. The regenerating optic axons reach to the optic tectum 1 month and thereafter the visual function recovers 3-4 months after axotomy. Therefore, we followed up spike activities of ganglion cells in the carp retina during optic nerve regeneration. The spike activity of ganglion cells (both types of ON and OFF cells) suddenly declined by less than 20% of the control value in frequency 5 days after nerve injury. The spike frequency at 50 days after axotomy was 50% of the control and it was recovered to control level at 100 days after axotomy. In contrast, the area-dependency of ganglion cells to various spots of central light stimuli (0.3 mm-4 mm in diameter) recovered a little bit more later. The area-dependency of ganglion cell response could never be seen 5-50 days after optic nerve transection. The normal area-dependency of ganglion cell response could be only seen just 100 days after optic nerve injury. On the other hand, horizontal cell response (S-potentials) in the carp retina did not change both in amplitude and in area dependency during this long period (0-100 days) after optic nerve transection. These results strongly indicate that the recovery of area-dependency of ganglion cells in the carp retina is just well correlated with that of visual function from the optic nerve injury and horizontal cell activities in the outer retina are not affected during this period. [Jpn J Physiol 55 Suppl:S166 (2005)]
