Behavioral tests of compression of retinotectal projection after partial tectal ablation in goldfish

Some determinants of optic terminal localization and retinotopic polarity within fibre populations in the tectum of goldfish.

“…Gaze & Sharma (1970) were the first to describe reorganization of the retinotectal projection following removal of the caudal tectum in goldfish which proves that, whatever mechanisms normally guide specific fibres to appropriate termination sites, these are not based on any unique invariant selective affinity. One of their observations, that the full retinotopic projection is reconstituted in a 'compressed' fashion on the remaining tectal fragment, has been confirmed in many similar studies (Yoon, 1971(Yoon, , 1972a(Yoon, , b, 1975(Yoon, , 1976 Meyer & Scott, 1977; Marotte, Wye-Dvorak & Mark, 1977; Cook, 1979; Wye-Dvorak, Marotte & Mark, 1979). However they also reported that in cases where the optic nerve was not undergoing regeneration a subpopulation of fibres which would normally terminate in the caudal tectum came to form a 'duplicate' ordered projection superimposed on the normal projection to the remaining rostal tectum.…”

“…We had to take into account a number of other extraneous factors which have been shown recently to affect the occurrence of compression and might therefore also have accounted for discrepancies in the appearance of duplication. Thus we compared fish kept in constant and diurnal lighting conditions since it has been reported that continuous illumination can prevent compression and other manifestations of plasticity (Yoon, 1975;Beazley & Humphrey, 1980;Marotte et al 1981) although others have failed to replicate the effect (Arora & Grinnell, 1976;Marotte et al 1977;Meyer, 1977;Meyer & Scott, 1977;Scott, 1977). Furthermore, Wye-Dvorak et al (1979) have shown that compression (or duplication of fields) seldom occurs in fish operated in autumn although there are occasionally exceptions among large and small fish kept in constant light (Marotte et al 1981).…”