Davidson M C, Horvitz J C, Tottenham N, Fossella J A, Watts R, Uluğ A M, Casey B J
Sackler Institute for Devevelopmental Psychobiology, Weill Medical College of Cornell University, 1300 York Avenue, Box 140, New York, NY 10021, USA.
Neuroimage. 2004 Nov;23(3):1039-45. doi: 10.1016/j.neuroimage.2004.07.049.
This study examined the effects of varying the predictability of nonrewarding events on behavior and neural activation using a rapid mixed-trial functional magnetic resonance imagery (fMRI) design. Twelve adult subjects were scanned with echo planar imaging during performance of a visual detection task where the probability of events (target and nontarget) varied. This task included expected and unexpected nonrewarding events (expected target, unexpected nontarget, and omission of target) in a design that closely parallels studies of dopamine function and reward processing in the alert monkey. We predicted that activation in dopamine-rich areas of the forebrain would behave like the animal literature shows that dopamine neurons in the midbrain behave. Specifically, we predicted increased activity in these regions when an unexpected event occurred and decreased activity when an expected event was omitted. Two main regions, the anterior cingulate and dorsal striatum, showed this pattern. The response in these regions was distinguished by enhanced anterior cingulate activity following the occurrence of an unexpected event and greater suppression of caudate activity following the omission of an expected event. These results suggest that neural activity within specific dopamine-rich brain regions can be modulated by violations in the expectation of nonrewarding events and that the direction of the modulation depends on the nature of the violations.
本研究采用快速混合试验功能磁共振成像（fMRI）设计，考察了改变无奖励事件的可预测性对行为和神经激活的影响。在12名成年受试者执行视觉检测任务期间，采用回波平面成像进行扫描，其中事件（目标和非目标）的概率有所变化。该任务在设计上包含预期和意外的无奖励事件（预期目标、意外非目标和目标遗漏），这与警觉猴子的多巴胺功能和奖励处理研究非常相似。我们预测，前脑富含多巴胺区域的激活情况将与动物研究文献中显示的中脑多巴胺神经元的表现相似。具体而言，我们预测当意外事件发生时，这些区域的活动会增加，而当预期事件被遗漏时，活动会减少。两个主要区域，即前扣带回和背侧纹状体，呈现出这种模式。这些区域的反应特点是，意外事件发生后前扣带回活动增强，预期事件遗漏后尾状核活动受到更大抑制。这些结果表明，特定富含多巴胺的脑区内的神经活动可因无奖励事件预期的违背而受到调节，且调节方向取决于违背的性质。
