Changes in pattern discrimination learning induced by visual deprivation in normal and commissurotomized pigeons

Abstract

The effect of monocular (MD), binocular (BD) and alternating monocular (AMD) deprivation on monocular pattern discrimination learning and interocular transfer was investigated in pigeons reared with intact and sectioned supraoptic decussation (DSO). In BD and AMD animals acquisition and interocular transfer of two different pattern discrimination problems remained as good as in the control animals (CO). Monocularly deprived animals (MDE) required significantly more trials to learn the discriminations through the deprived eye, when it was trained first, and interocular transfer from the deprived to the experienced eye was absent. However, if the experienced eye was trained first (MED), learning with the deprived eye was at least as rapid as with the experienced eye. This indicates positive interocular transfer from the experienced to the deprived eye. Interocular transfer of pattern discriminations was completely blocked by section of the DSO in both adults (DSOad) and newly hatched animals (DSOjuv). The elimination of binocular interaction by commissurotomy from the beginning of the postnatal life failed to produce an impaired pattern discrimination learning in monocularly deprived animals (MD+DSO). The results are discussed in terms of competition between the projections from both eyes in the visual Wulst.