Engelmann Jan B, Tamir Diana
Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 101 Woodruff Circle, Atlanta, GA 30329, USA.
Brain Res. 2009 Sep 22;1290:28-51. doi: 10.1016/j.brainres.2009.06.078. Epub 2009 Jul 2.
We investigated the neural correlates of subjective valuations during a task involving risky choices about lotteries. Because expected value was held constant across all lotteries, decisions were influenced by subjective preferences, which manifest behaviorally as risk-seeking or risk-averse attitudes. To isolate structures encoding risk preference during choice, we probed for areas showing increased activation as a function of selected risk-level. Such response patterns were obtained in anterior (ACC) and posterior cingulate cortex (PCC), superior frontal gyrus, caudate nucleus, and substantia nigra. Behavioral results revealed the presence of risk-averse and risk-neutral individuals. In parallel, brain signals revealed modulation of activity by risk attitude during choice. Correlations between risk-seeking attitudes and neural activity during risky choice were obtained in superior and inferior frontal gyri, medial and lateral orbitofrontal cortex, and parahippocampal gyrus, while correlations with risk-averse attitudes were found in the caudate. The dynamics of neural responses relevant to each stage of the task (decision, anticipation, outcome) were investigated via timeseries and conjunction analyses. Though the networks engaged in each of the task stages were mostly distinct, regions within ACC, PCC and caudate were consistently activated during each decision-making phase. These results demonstrate (1) that subjective assessments of risk, as well as individual attitudes toward risk, play a significant role in modulating activity within brain regions recruited during decision-making, and (2) that ACC, PCC and caudate are relevant during each phase of a decision-making task requiring subjective valuations, strengthening the role of these regions in self-referential subjective valuations during choice.
我们在一项涉及彩票风险选择的任务中研究了主观估值的神经关联。由于所有彩票的期望值保持不变,决策受主观偏好影响,主观偏好表现为行为上的风险寻求或风险规避态度。为了分离出在选择过程中编码风险偏好的结构,我们探究了随着所选风险水平增加而激活增强的区域。在前扣带回皮质(ACC)、后扣带回皮质(PCC)、额上回、尾状核和黑质中获得了这样的反应模式。行为结果显示存在风险规避和风险中性个体。同时,大脑信号显示在选择过程中活动受风险态度调节。在额上回和额下回、眶额内侧皮质和外侧皮质以及海马旁回中获得了风险寻求态度与风险选择过程中神经活动的相关性,而在尾状核中发现了与风险规避态度的相关性。通过时间序列和联合分析研究了与任务各阶段(决策、预期、结果)相关的神经反应动态。尽管参与每个任务阶段的网络大多不同,但在每个决策阶段,ACC、PCC和尾状核内的区域持续被激活。这些结果表明:(1)风险的主观评估以及个体对风险的态度在调节决策过程中所涉及脑区的活动方面发挥着重要作用;(2)在需要主观估值的决策任务的每个阶段,ACC、PCC和尾状核都发挥作用,强化了这些区域在选择过程中自我参照主观估值中的作用。