脳の学習プロセスを解明(Groundbreaking Study Uncovers How Our Brain Learns)

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2025-04-17 カリフォルニア大学サンディエゴ校(UCSD)

カリフォルニア大学サンディエゴ校の研究チームは、学習中に脳内のシナプスがどのように変化するかを2光子イメージングなどの高度な手法で観察し、従来の「すべてのシナプスが同じルールで可塑性を示す」という仮説を覆した。個々のニューロンが部位ごとに異なる計算ルールを同時に用いることが明らかとなり、脳が情報を学習する際の「クレジット割当問題」に新たな視点を提供。この成果は、神経疾患(認知症、PTSD、自閉症など)の治療や、AIシステムの構築にも応用可能性がある。

<関連情報>

運動学習におけるシナプス消去の局所的・大域的予測因子 Local and global predictors of synapse elimination during motor learning

Science Advances  Published:15 Mar 2024
DOI:https://doi.org/10.1126/sciadv.adk0540

脳の学習プロセスを解明(Groundbreaking Study Uncovers How Our Brain Learns)

Abstract

During learning, synaptic connections between excitatory neurons in the brain display considerable dynamism, with new connections being added and old connections eliminated. Synapse elimination offers an opportunity to understand the features of synapses that the brain deems dispensable. However, with limited observations of synaptic activity and plasticity in vivo, the features of synapses subjected to elimination remain poorly understood. Here, we examined the functional basis of synapse elimination in the apical dendrites of L2/3 neurons in the primary motor cortex throughout motor learning. We found no evidence that synapse elimination is facilitated by a lack of activity or other local forms of plasticity. Instead, eliminated synapses display asynchronous activity with nearby synapses, suggesting that functional synaptic clustering is a critical component of synapse survival. In addition, eliminated synapses show delayed activity timing with respect to postsynaptic output. Thus, synaptic inputs that fail to be co-active with their neighboring synapses or are mistimed with neuronal output are targeted for elimination.

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