题目：Excitatory-inhibitory balance governs stability of perceptual learning

报告人：Kazuhisa Shibata, Ph.D

时间：2017年12月05日 星期二 13:00-14:30

地点： 北京大学王克桢楼1113

The visual system of the brain constantly suffers from the so-called “plasticity-stability dilemma”. How is the visual system sufficiently plastic to learn new information processing of a visual stimulus, but stable enough to protect the learned information processing from being destroyed by a newly exposed visual stimulus? In this talk, I will present two of our recent studies that tested the validity of the following hypothesis: stability of visual perceptual learning (VPL) is governed by the ratio of excitatory to inhibitory neuromodulators (E/I ratio) in the visual cortex. In the first study (Shibata et al., Nat Neurosci, 2017), we examined relationships between E/I ratios in the visual cortex and consolidation, a process by which fragile VPL becomes stabilized. Results of psychophysical experiments revealed two distinct consolidation processes of VPL depending on the amounts of training of a visual task. The two consolidation processes were closely related to ratios of the concentrations of glutamate (excitatory neuromodulator) and GABA (inhibitory neuromodulator) in early visual areas, as measured by magnetic resonance spectroscopy. These results are consistent with the hypothesis that E/I ratio governs stability of VPL. In the second study (Bang et al., under revision), we examined whether this mechanism can also apply to reactivation-reconsolidation processes. We found that retrieval of previously consolidated VPL (reactivation) renders the VPL labile again and subject to disruption by new learning unless the VPL go through a further consolidation process (reconsolidation). E/I ratios in early visual areas showed the basically same pattern as during consolidation. The findings of the two studies provide the following two important implications regarding the plasticity-stability dilemma. First, stability of learning is governed by E/I ratios of a brain area that is involved in the learning. Second, processes for reconsolidation after reactivation and consolidation have common mechanisms in both human behavior and neurochemical levels.

邀请人：余聪教授