Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143, USA.
J Cogn Neurosci. 2011 Jun;23(6):1437-46. doi: 10.1162/jocn.2010.21466. Epub 2010 May 13.
Selective processing of task-relevant stimuli is critical for goal-directed behavior. We used electrocorticography to assess the spatio-temporal dynamics of cortical activation during a simple phonological target detection task, in which subjects press a button when a prespecified target syllable sound is heard. Simultaneous surface potential recordings during this task revealed a highly ordered temporal progression of high gamma (HG, 70-200 Hz) activity across the lateral hemisphere in less than 1 sec. The sequence demonstrated concurrent regional sensory processing of speech syllables in the posterior superior temporal gyrus (STG) and speech motor cortex, and then transitioned to sequential task-dependent processing from prefrontal cortex (PFC), to the final motor response in the hand sensorimotor cortex. STG activation was modestly enhanced for target over nontarget sounds, supporting a selective gain mechanism in early sensory processing, whereas PFC was entirely selective to targets, supporting its role in guiding response behavior. These results reveal that target detection is not a single cognitive event, but rather a process of progressive target selectivity that involves large-scale rapid parallel and serial processing in sensory, cognitive, and motor structures to support goal-directed human behavior.
选择性处理与任务相关的刺激对于目标导向行为至关重要。我们使用脑电描记术来评估在一个简单的语音目标检测任务中皮质激活的时空动力学，在此任务中，当听到预定的目标音节声音时，受试者按下按钮。在这个任务中同时进行的表面电位记录显示，在不到 1 秒的时间内，高伽马（HG，70-200 Hz）活动在外侧半球以高度有序的时间顺序进行。该序列展示了在后上颞叶（STG）和言语运动皮层中对语音音节的同时区域感觉处理，然后从前额叶皮层（PFC）过渡到手部感觉运动皮层中的最终运动反应，这是一个序列相关的处理过程。对于目标声音而非非目标声音，STG 的激活略有增强，支持了早期感觉处理中的选择性增益机制，而 PFC 则完全针对目标，支持了它在指导反应行为中的作用。这些结果表明，目标检测不是一个单一的认知事件，而是一个渐进的目标选择性过程，涉及到感觉、认知和运动结构中的大规模快速并行和串行处理，以支持目标导向的人类行为。
