ドーパミンが悪い結果を避ける学習に与える影響を解明(How dopamine helps us learn to avoid bad outcomes)

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2025-04-15 ノースウェスタン大学

ノースウェスタン大学の研究で、ドーパミンが悪い結果を避ける学習に重要な役割を果たすことが明らかにされた。マウスに警告音を用いた実験で、側坐核の2領域(腹内側シェルとコア)のドーパミン活動を記録。腹内側シェルでは回避学習が進むにつれドーパミン反応が変化し、最終的には消失。コアでは警告音や不快刺激に反応してドーパミンが減少し、学習の進行とともに変化した。これにより、ドーパミンは快楽だけでなく、危険回避の学習にも関与し、不安障害などの理解にも貢献する可能性が示唆された。

<関連情報>

側坐核ドーパミンの領域特異的シグナルは回避学習の異なる側面をコードする Region-specific nucleus accumbens dopamine signals encode distinct aspects of avoidance learning

Gabriela C. Lopez ∙ Louis D. Van Camp ∙ Ryan F. Kovaleski ∙ … ∙ Venus N. Sherathiya ∙ Julia M. Cox ∙ Talia N. Lerner
Current Biology  Published:April 22, 2025
DOI:https://doi.org/10.1016/j.cub.2025.04.006

Graphical abstract

ドーパミンが悪い結果を避ける学習に与える影響を解明(How dopamine helps us learn to avoid bad outcomes)

Highlights

  • Core and vmShell dopamine display distinct dynamics during avoidance learning
  • Core dopamine responses to warning cues strengthen during expert performance
  • vmShell dopamine responses to shocks and cues are present early but later fade
  • Escapable and inescapable shock protocols elicit distinct dopamine responses

Summary

Avoidance learning—learning to avoid bad outcomes—is an essential survival behavior. Dopamine signals are widely observed in response to aversive stimuli, indicating they could play a role in learning about how to avoid these stimuli.1,2,3,4,5 However, it is unclear what computations dopamine signals perform to support avoidance learning. Furthermore, substantial heterogeneity in dopamine responses to aversive stimuli has been observed across nucleus accumbens (NAc) subregions.3,6,7,8 To understand how heterogeneous dopamine responses to aversive stimuli contribute to avoidance learning, we recorded NAc core (Core) and NAc ventromedial shell (vmShell) dopamine during a task in which mice could avoid a footshock punishment by moving to the opposite side of a 2-chamber apparatus during a 5-s warning cue. Both signals evolved substantially—but differently—with learning. We found that Core and vmShell dopamine signals responded oppositely to shocks at the beginning of training and oppositely to warning cues as cue-shock associations developed in mid-training. Core dopamine responses strengthen with learning and are especially evident during expert performance. vmShell dopamine responses to cues and shocks were present during early learning but were not sustained during expert performance. Our data support a model in which Core dopamine encodes prediction errors that guide the consolidation of avoidance learning, while vmShell dopamine guides initial cue-shock associations by signaling aversive salience.

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