Reduced Inhibitory Lateral Interactions by Perceptual Learning in Normal Subjects

2 Introduction 1. Perceptual learning By discussing perceptual learning, it should be useful to clarify what does it represents. According to Gibson (1963), perceptual learning is form of long-term learning in the perceptual system (not cognitive), which, because of the practice, increases capacity to respond to the stimuli from the ambient. 1. a) How and where perceptual learning occurs If perceptual learning really occurs then it should happen somewhere. The following discussion tries to elucidate the location and processes of perceptual learning. Hubel and Wiesel (Hubel, 1995) discovered that the cells in the cat’s occipital cortex in area V1 respond to the basics characteristics of the stimuli, such as contrast, orientation and movement. Therefore, the question is whether perceptual learning occurs at this early level of information processing, or at some more advanced level of information processing, where neurons respond to complex features of the stimuli. A number of psychophysical researches have been conducted to elucidate this dilemma. The common paradigm in all these experiments was to present, for some time period, the same stimuli at the same position, after which should be tested whether the learning really occurred, and if it was, whether is transferable (to another eye, or retinal position or orientation), or not. It is supposed that if the experimental results support that learning occurred, but that is not transferable between eyes, retinotopic position or orientation, than it could be inferred that learning really occurred in V1, because only at this level of processing information from both eyes do not merge together, as well as is retained retinotopic position (Hubel, 1995). However, if results show that what is learned with one eye, transfers to the other, or if the stimulus is presented at one part of the retina and the effects of learning are noticeable when the stimulus is presented to another, or if it could be evident for different orientation, or movement, it would be concluded that these information about stimuli merged together before have been remembered, and therefore learning occurred at the higher level of processing.