Pattern of retinotectal connections after retinal regeneration.

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Abstract
The pattern of connections established within the optic tectum of Triturus vulgaris by regenerating optic nerve fibers was determined electrophysiologically at different time intervals after retinal regeneration. After a 5-month period of recovery the tectal representation of the peripheral area of the visual field was diffuse, but the projection to the tectum from the center of the retina appeared to have regained a normal pattern of connections. Recovery later spread to tectal regions representing peripheral areas of the retina, and eventually, after a 9-month period of recovery, the entire pattern of retinotectal connections was normal. Moreover, microelectrode recordings of single optic nerve fibers in the 5-month group indicated that the retina was functionally normal, hence the anomalies in the retinotectal projection recorded in this group could not be attributed to defects in the recently regenerated retina. These results are discussed in relation to Sperry''s theory that specific affinities govern the selective formation of connections between ingrowing optic fibers and the central neurons upon which they impinge.