研究
聴皮質の時空間的神経活動の状況依存的な可塑性
2007 年 45 巻 1 号 p. 17-26
詳細
2007 年 45 巻 1 号 p. 17-26
As cognition changes according to the context, cortical neural representation may also depend on the context. We proposed a novel context-dependent fear conditioning experiment and investigated learning-induced plasticity of neural representations in the primary, anterior and ventral auditory fields (A1, AAF and VAF) in rat cortices. Only when background white noise was presented, rats received an electric shock to the foot as an unconditioned stimulus (US), which was associated with a tone as a conditioned stimulus (CS). In contrast, rats never received US in silence. After conditioning, freezing time tended to be longer when CS was presented under noise, suggesting that rats learned the context-dependent semantic change of sound information. An electrophysiological study revealed the post-conditioning neural activities in A1 and AAF had temporal differences between “in silence” and “under noise” conditions, while VAF showed spatial differences in tonotopic representation. These results suggest that the auditory cortex represents the sound information differently according to the context and that each auditory field plays a different role in the comprehension of context. Especially, taken together with previous studies, VAF possibly encodes the most important sound information for survival.
