Kondo Hirohito M, Oba Takeyuki, Ezaki Takahiro, Kochiyama Takanori, Shimada Yasuhiro, Ohira Hideki
School of Psychology, Chukyo University, Nagoya, Aichi, Japan.
Graduate School of Informatics, Nagoya University, Nagoya, Aichi, Japan.
Front Neurosci. 2024 Jul 31;18:1439656. doi: 10.3389/fnins.2024.1439656. eCollection 2024.
Decision-making under risk is a common challenge. It is known that risk-taking behavior varies between contexts of reward and punishment, yet the mechanisms underlying this asymmetry in risk sensitivity remain unclear.
This study used a monetary task to investigate neurochemical mechanisms and brain dynamics underpinning risk sensitivity. Twenty-eight participants engaged in a task requiring selection of visual stimuli to maximize monetary gains and minimize monetary losses. We modeled participant trial-and-error processes using reinforcement learning.
Participants with higher subjective utility parameters showed risk preference in the gain domain ( = -0.59) and risk avoidance in the loss domain ( = -0.77). Magnetic resonance spectroscopy (MRS) revealed that risk avoidance in the loss domain was associated with γ-aminobutyric acid (GABA) levels in the ventral striatum ( = -0.42), but not in the insula ( = -0.15). Using functional magnetic resonance imaging (fMRI), we tested whether risk-sensitive brain dynamics contribute to participant risky choices. Energy landscape analyses demonstrated that higher switching rates between brain states, including the striatum and insula, were correlated with risk avoidance in the loss domain ( = -0.59), a relationship not observed in the gain domain ( = -0.02).
These findings from MRS and fMRI suggest that distinct mechanisms are involved in gain/loss decision making, mediated by subcortical neurometabolite levels and brain dynamic transitions.
风险下的决策是一项常见挑战。已知冒险行为在奖励和惩罚情境中有所不同，然而这种风险敏感性不对称背后的机制仍不清楚。
本研究使用一项金钱任务来探究支持风险敏感性的神经化学机制和脑动力学。28名参与者参与了一项任务，该任务要求选择视觉刺激以最大化金钱收益并最小化金钱损失。我们使用强化学习对参与者的试错过程进行建模。
主观效用参数较高的参与者在收益领域表现出风险偏好（= -0.59），在损失领域表现出风险规避（= -0.77）。磁共振波谱（MRS）显示，损失领域的风险规避与腹侧纹状体中的γ-氨基丁酸（GABA）水平相关（= -0.42），但与脑岛中的GABA水平无关（= -0.15）。使用功能磁共振成像（fMRI），我们测试了风险敏感的脑动力学是否有助于参与者的风险选择。能量景观分析表明，包括纹状体和脑岛在内的脑状态之间较高的转换率与损失领域的风险规避相关（= -0.59），而在收益领域未观察到这种关系（= -0.02）。
这些来自MRS和fMRI的发现表明，不同的机制参与了收益/损失决策，由皮质下神经代谢物水平和脑动态转换介导。
