The neural mechanism of stabilization of perceptual learning revealed by the concentration of excitatory and inhibitory neurotrasmitter

Abstract

Visual perceptual learning (VPL) is regarded as a manifestation of experience-dependent plasticity in the visual/brain system. It has been found that VPL of a task is disrupted or interfered with by training of a new task if the interval between the two training was less than one hour (Seitz et al, PNAS, 2005). This retrograde interference effect suggests that after training is over, it takes up to one hour for VPL to be stabilized. However, another study has found that first training also interferes with VPL of second training (Yotsumoto et al, Vis Res, 2009), indicating that the mechanism of interference and its relationship with stabilization process after VPL training is more complex than it was originally thought. The purpose of the present study is to resolve the puzzle and better clarify the underlying mechanism of stabilization and interference. In the first experiment, a detection task on a different orientation was repeatedly performed in each of the first and second training. There was no interval between the two trainings. The subjects who underwent 8-block training (N=12) showed retrograde interference, whereas the subjects who underwent 16-block training (N=12) showed anterograde interference. In the second experiment, we measured the concentration of excitatory and inhibitory neurotransmitters in the early visual cortex as a function of the length of training on an orientation detection task using magnetic resonance spectroscopy. The E(xicitaotry)/I(nhibitory) ratio defined by the concentration of glutamate divided by that of GABA was significantly higher after the 8-block training than before the training (N=12), whereas it was significantly lower after the 16-block training (N=12). These results are in accord with the hypothesis that a lower E/I ratio is associated with greater resilience against being interfered with and therefore greater stability of VPL.

Meeting abstract presented at VSS 2015