Hosking Jay G, Floresco Stan B, Winstanley Catharine A
Department of Psychology, University of British Columbia, Vancouver, BC, Canada.
Neuropsychopharmacology. 2015 Mar;40(4):1005-15. doi: 10.1038/npp.2014.285. Epub 2014 Oct 20.
Successful decision making often requires weighing a given option's costs against its associated benefits, an ability that appears perturbed in virtually every severe mental illness. Animal models of such cost/benefit decision making overwhelmingly implicate mesolimbic dopamine in our willingness to exert effort for a larger reward. Until recently, however, animal models have invariably manipulated the degree of physical effort, whereas human studies of effort have primarily relied on cognitive costs. Dopamine's relationship to cognitive effort has not been directly examined, nor has the relationship between individuals' willingness to expend mental versus physical effort. It is therefore unclear whether willingness to work hard in one domain corresponds to willingness in the other. Here we utilize a rat cognitive effort task (rCET), wherein animals can choose to allocate greater visuospatial attention for a greater reward, and a previously established physical effort-discounting task (EDT) to examine dopaminergic and noradrenergic contributions to effort. The dopamine antagonists eticlopride and SCH23390 each decreased willingness to exert physical effort on the EDT; these drugs had no effect on willingness to exert mental effort for the rCET. Preference for the high effort option correlated across the two tasks, although this effect was transient. These results suggest that dopamine is only minimally involved in cost/benefit decision making with cognitive effort costs. The constructs of mental and physical effort may therefore comprise overlapping, but distinct, circuitry, and therapeutic interventions that prove efficacious in one effort domain may not be beneficial in another.
成功的决策往往需要权衡给定选项的成本与其相关收益,而这种能力在几乎每一种严重精神疾病中似乎都受到了干扰。在这种成本/收益决策的动物模型中,中脑边缘多巴胺在很大程度上影响着我们为获得更大奖励而付出努力的意愿。然而,直到最近,动物模型一直都是在操纵体力付出的程度,而关于努力的人体研究主要依赖于认知成本。多巴胺与认知努力之间的关系尚未得到直接研究,个体在付出脑力与体力努力方面的意愿之间的关系也未得到研究。因此,尚不清楚在一个领域努力工作的意愿是否与另一个领域的意愿相对应。在这里,我们利用大鼠认知努力任务(rCET),即动物可以选择为了更大的奖励而分配更多的视觉空间注意力,以及一个先前建立的体力努力折扣任务(EDT),来研究多巴胺能和去甲肾上腺素能对努力的贡献。多巴胺拮抗剂依托必利和SCH23390均降低了在EDT上付出体力努力的意愿;这些药物对在rCET上付出脑力努力的意愿没有影响。在这两个任务中,对高努力选项的偏好存在相关性,尽管这种影响是短暂的。这些结果表明,多巴胺在涉及认知努力成本的成本/收益决策中只起到了最小的作用。因此,脑力和体力努力的结构可能包含重叠但不同的神经回路,在一个努力领域被证明有效的治疗干预措施在另一个领域可能并无益处。