Ho Tiffany C, Brown Scott, Serences John T
Perception and Cognition Laboratory, Department of Psychology, University of California, San Diego, La Jolla, California 92093, USA.
J Neurosci. 2009 Jul 8;29(27):8675-87. doi: 10.1523/JNEUROSCI.5984-08.2009.
To successfully interact with objects in the environment, sensory evidence must be continuously acquired, interpreted, and used to guide appropriate motor responses. For example, when driving, a red light should motivate a motor command to depress the brake pedal. Single-unit recording studies have established that simple sensorimotor transformations are mediated by the same neurons that ultimately guide the behavioral response. However, it is also possible that these sensorimotor regions are the recipients of a modality-independent decision signal that is computed elsewhere. Here, we used functional magnetic resonance imaging and human observers to show that the time course of activation in a subregion of the right insula is consistent with a role in accumulating sensory evidence independently from the required motor response modality (saccade vs manual). Furthermore, a combination of computational modeling and simulations of the blood oxygenation level-dependent response suggests that this region is not simply recruited by general arousal or by the tonic maintenance of attention during the decision process. Our data thus raise the possibility that a modality-independent representation of sensory evidence may guide activity in effector-specific cortical areas before the initiation of a behavioral response.
为了成功地与环境中的物体进行交互，必须持续获取、解读感觉证据，并将其用于指导适当的运动反应。例如，驾驶时，红灯应促使发出踩下刹车踏板的运动指令。单细胞记录研究表明，简单的感觉运动转换是由最终指导行为反应的相同神经元介导的。然而，这些感觉运动区域也有可能是在其他地方计算出的与感觉模态无关的决策信号的接收者。在这里，我们使用功能磁共振成像和人类观察者来表明，右侧脑岛一个子区域的激活时间进程与独立于所需运动反应模态（扫视与手动）积累感觉证据的作用一致。此外，结合计算建模和对血氧水平依赖反应的模拟表明，该区域并非简单地由一般唤醒或决策过程中注意力的持续性维持所招募。因此，我们的数据提出了一种可能性，即在行为反应开始之前，与感觉模态无关的感觉证据表征可能会指导效应器特异性皮层区域的活动。
