Lesser Ronald P, Lee Hyang Woon, Webber W R S, Prince Barry, Crone Nathan E, Miglioretti Diana L
Department of Neurology, Johns Hopkins Uiversity, Baltimore, MD 21287-7247, USA.
Brain. 2008 Jun;131(Pt 6):1528-39. doi: 10.1093/brain/awn044. Epub 2008 Mar 12.
Patterns of responses in the cerebral cortex can vary, and are influenced by pre-existing cortical function, but it is not known how rapidly these variations can occur in humans. We investigated how rapidly response patterns to electrical stimulation can vary in intact human brain. We also investigated whether the type of functional change occurring at a given location with stimulation would help predict the distribution of responses elsewhere over the cortex to stimulation at that given location. We did this by studying cortical afterdischarges following electrical stimulation of the cortex in awake humans undergoing evaluations for brain surgery. Response occurrence and location could change within seconds, both nearby to and distant from stimulation sites. Responses might occur at a given location during one trial but not the next. They could occur at electrodes adjacent or not adjacent to those directly stimulated or to other electrodes showing afterdischarges. The likelihood of an afterdischarge at an individual site after stimulation was predicted by spontaneous electroencephalographic activity at that specific site just prior to stimulation, but not by overall cortical activity. When stimulation at a site interrupted motor, sensory or language function, afterdischarges were more likely to occur at other sites where stimulation interrupted similar functions. These results show that widespread dynamic changes in cortical responses can occur in intact cortex within short periods of time, and that the distribution of these responses depends on local brain states and functional brain architecture at the time of stimulation. Similar rapid variations may occur during normal intracortical communication and may underlie changes in the cortical organization of function. Possibly these variations, and the occurrence and distribution of responses to cortical stimulation, could be predicted. If so, interventions such as stimulation might be used to alter spread of epileptogenic activity, accelerate learning or enhance cortical reorganization after brain injury.
大脑皮层的反应模式可能会有所不同，并受先前存在的皮层功能影响，但目前尚不清楚这些变化在人类中能多快发生。我们研究了在完整的人脑中，对电刺激的反应模式能多快发生变化。我们还研究了在给定位置进行刺激时发生的功能变化类型是否有助于预测皮层其他位置对该给定位置刺激的反应分布。我们通过研究在接受脑部手术评估的清醒人类中，皮层电刺激后的皮层放电后效应来进行此项研究。反应的发生和位置可能在几秒钟内发生变化，无论是在刺激部位附近还是远处。在一次试验中，反应可能在给定位置出现，但在下一次试验中则不会。它们可能在与直接受刺激电极相邻或不相邻的电极处，或者在显示放电后效应的其他电极处发生。刺激后单个部位出现放电后效应的可能性可由刺激前该特定部位的自发脑电图活动预测，但不能由整体皮层活动预测。当在某一部位的刺激中断运动、感觉或语言功能时，放电后效应更有可能在其他刺激中断类似功能的部位出现。这些结果表明，完整皮层内的皮层反应可在短时间内发生广泛的动态变化，并且这些反应的分布取决于刺激时的局部脑状态和功能性脑结构。类似的快速变化可能在正常的皮层内通信过程中发生，并可能是功能皮层组织变化的基础。这些变化以及对皮层刺激的反应的发生和分布可能是可以预测的。如果是这样，诸如刺激等干预措施可能会被用于改变致痫活动的传播、加速学习或增强脑损伤后的皮层重组。
