Desmedt J E, Tomberg C
Brain Research Unit, University of Brussels Faculty of Medicine, Belgium.
Electroencephalogr Clin Neurophysiol. 1989 Sep-Oct;74(5):321-46. doi: 10.1016/0168-5597(89)90001-4.
Detailed procedures are described for the study of somatosensory event-related potentials (ERPs) to electric stimulation of fingers. Control responses to homogeneous (100%) series of identical stimuli (thus eliminating input mismatch) while the subject reads a novel (thus providing a distinct attention-capturing activity and maintaining vigilance level) are validated as reflecting the exogenous obligatory profiles required for assessing cognitive component in ERPs to target relevant stimuli. With these 'neutral' conditions, the control responses have a similar profile even at larger ISIs such as those separating the infrequent targets in Attention runs. Conversely, series of stimuli identical to those in control runs can elicit cognitive components in a 'Lie' experiment when the subject is induced to treat the stimuli like targets even though there is no discrimination involved. On this basis, the somatosensory P30, P40, P100 and N140 components appearing in the target profiles are considered genuine cognitive components. They have been analyzed with scatter displays, electronic subtraction, bit-mapped displays and with calculation of Z and dilation factors. The cognitive P30 and P40 reflect selective attention-related enhancements of the neural generators in receiving somatosensory cortex. The early parietal positivity P27 can thus be modulated separately from the frontal N30 component and is thought to be generated by a radial dipole in area 1. The later cognitive P100 and N140 reflect the invocation of distinct processors in conjunction with the behavioral use of the sensory input. The evolving topographical patterns of the P100 and N140 electrogeneses, revealed by bit-mapped data, suggest complex interactions between posterior parietal and prefrontal cortex whereby the sensory information is placed into spatial coordinate systems and matched with representations of relevant objects or relationships in space for target processing in the sequential tasks.
本文描述了用于研究手指电刺激体感事件相关电位（ERP）的详细程序。当受试者阅读一本小说时（从而提供一种独特的吸引注意力的活动并维持警觉水平），对相同刺激的同质（100%）系列的对照反应（从而消除输入不匹配）被验证为反映了评估目标相关刺激ERP中认知成分所需的外源性强制性特征。在这些“中性”条件下，即使在较大的刺激间隔（ISI）下，如在注意力测试中分隔罕见目标的ISI，对照反应也具有相似的特征。相反，与对照测试中相同的一系列刺激在“说谎”实验中可以引发认知成分，此时受试者被诱导将刺激视为目标，即使不涉及辨别。在此基础上，目标特征中出现的体感P30、P40、P100和N140成分被认为是真正的认知成分。它们已通过散点图显示、电子减法、位图显示以及Z和扩张因子的计算进行了分析。认知P30和P40反映了体感皮层中神经发生器与选择性注意相关的增强。因此，早期顶叶正波P27可以与额叶N30成分分开调节，并且被认为是由区域1中的径向偶极产生的。后期认知P100和N140反映了与感觉输入的行为使用相结合的不同处理器的调用。位图数据揭示的P100和N140电发生的不断演变的地形模式表明，后顶叶和前额叶皮层之间存在复杂的相互作用，由此感觉信息被放入空间坐标系中，并与空间中相关物体或关系的表征相匹配，以便在顺序任务中进行目标处理。
