Post eye-opening maturation of visual receptive field diameters in the superior colliculus of normal- and dark-reared rats

When the rat's eyes open (P14) the retino-collicular projection is largely mature but the cortico-collicular afferents are naive and mature considerably in the following week. At P14, single units in the superior colliculus' superficial grey layer (SGS) had discrete receptive fields (RFs) (diameter = 15 +/- 1.6 degrees) which expanded with age, reaching 30 +/- 2.6 degrees at P21, possibly reflecting the increasing influence of the visual cortex, whose RFs are known to be enlarged at P21. Subsequently SGS RFs retracted to 13 +/- 1.30 by P23. Dark-reared (DR) rats followed a similar but delayed developmental pattern, such that RFs were still large (27 +/- 3.4 degrees) at P24. By P30 however the RFs of DR rats were the same as those of normal adults. Thus visual experience accelerates the emergence of normal RFs in the SGS. (C) 1997 Elsevier Science B.V.