Starr A, Sandroni P, Michalewski H J
Department of Neurology, University of California, Irvine 92717.
Electroencephalogr Clin Neurophysiol. 1995 Jan;96(1):76-92. doi: 10.1016/0013-4694(94)00162-e.
Brain potentials were recorded from 12 normal subjects engaged in an auditory target detection task (target stimulus probability of 0.2, stimulus rate of 1 every 2 sec) when instructions were (1) to press a response button with the thumb of the dominant hand to each target or (2) to keep a mental count of each target. A pre-stimulus slow negative potential was identified before every stimulus except non-targets immediately after targets. The amplitude of the pre-stimulus negativity was significantly affected by task instructions and was up to 4 times larger during the button press than the mental count condition. In contrast, the amplitudes and latencies of the event-related components (N100, P200, N200 and P300), when slow potentials were removed by filtering, were not different as a function of press or count instructions. The immediately preceding stimulus sequence affected both the amplitude and onset latency of the pre-stimulus negativity; both measures increased as the number of preceding non-targets increased. The amplitude of the pre-stimulus negative shift to targets also increased significantly as RT speed decreased. The major portion of the pre-stimulus negative potential is considered a readiness potential (RP) reflecting preparations to make a motor response. The amplitude of the RP during the target detection task did not significantly lateralize in contrast to the RP accompanying self-paced movements.
从12名参与听觉目标检测任务的正常受试者身上记录脑电信号（目标刺激概率为0.2，刺激频率为每2秒1次），任务指令为：(1) 用优势手的拇指按下响应按钮对每个目标做出反应；(2) 对每个目标进行心算。在每个刺激（除了紧跟目标之后的非目标刺激）之前都识别出一个刺激前慢负电位。刺激前负电位的幅度受任务指令的显著影响，在按键反应时比心算条件下大4倍。相比之下，当通过滤波去除慢电位后，事件相关成分（N100、P200、N200和P300）的幅度和潜伏期，在按键或心算指令条件下并无差异。紧接在前的刺激序列影响刺激前负电位的幅度和起始潜伏期；随着前序非目标刺激数量的增加，这两个指标均升高。对目标的刺激前负向偏移幅度也随着反应时速度的降低而显著增加。刺激前负电位的主要部分被认为是反映做出运动反应准备状态的准备电位（RP）。与伴随自主节奏运动的准备电位相比，目标检测任务期间准备电位的幅度没有明显的偏侧化。
