Department of Neuroscience and Imaging, G. D'Annunzio University, Chieti, Italy; Institute for Advanced Biomedical Technologies, G. D'Annunzio Foundation, Chieti, Italy.
Eur J Neurosci. 2014 Apr;39(8):1370-83. doi: 10.1111/ejn.12511. Epub 2014 Mar 11.
During simple perceptual decisions, sensorimotor neurons in monkey fronto-parietal cortex represent a decision variable that guides the transformation of sensory evidence into a motor response, supporting the view that mechanisms for decision-making are closely embedded within sensorimotor structures. Within these structures, however, decision signals can be dissociated from motor signals, thus indicating that sensorimotor neurons can play multiple and independent roles in decision-making and action selection/planning. Here we used functional magnetic resonance imaging to examine whether response-selective human brain areas encode signals for decision-making or action planning during a task requiring an arbitrary association between face pictures (male vs. female) and specific actions (saccadic eye vs. hand pointing movements). The stimuli were gradually unmasked to stretch the time necessary for decision, thus maximising the temporal separation between decision and action planning. Decision-related signals were measured in parietal and motor/premotor regions showing a preference for the planning/execution of saccadic or pointing movements. In a parietal reach region, decision-related signals were specific for the stimulus category associated with its preferred pointing response. By contrast, a saccade-selective posterior intraparietal sulcus region carried decision-related signals even when the task required a pointing response. Consistent signals were observed in the motor/premotor cortex. Whole-brain analyses indicated that, in our task, the most reliable decision signals were found in the same neural regions involved in response selection. However, decision- and action-related signals within these regions can be dissociated. Differences between the parietal reach region and posterior intraparietal sulcus plausibly depend on their functional specificity rather than on the task structure.
在简单的感知决策中，猴子额顶叶皮层的感觉运动神经元代表了一个决策变量，该变量指导着将感觉证据转化为运动反应，支持了决策机制紧密嵌入感觉运动结构的观点。然而，在这些结构中，决策信号可以与运动信号分离，这表明感觉运动神经元可以在决策和动作选择/规划中发挥多种独立的作用。在这里，我们使用功能磁共振成像来研究在一项任务中，是否有与决策或动作计划相关的大脑区域编码信号，该任务要求在面孔图片（男性与女性）和特定动作（眼跳与手指出动作）之间建立任意关联。刺激逐渐呈现，以延长决策所需的时间，从而最大程度地延长决策与动作规划之间的时间间隔。在显示对眼跳或手指出动作的规划/执行有偏好的顶叶和运动/前运动区域中，测量了与决策相关的信号。在顶叶伸臂区域中，与首选的手指出反应相关联的刺激类别具有决策相关的信号特异性。相比之下，即使任务要求手指出反应，选择眼跳的后内顶叶沟区域也携带决策相关的信号。在运动/前运动皮层中观察到了一致的信号。全脑分析表明，在我们的任务中，最可靠的决策信号出现在涉及反应选择的相同神经区域中。然而，这些区域中的决策和动作相关信号可以分离。顶叶伸臂区域和后内顶叶沟区域之间的差异可能取决于它们的功能特异性，而不是任务结构。
