Schroeder C E, Tenke C E, Givre S J, Arezzo J C, Vaughan H G
Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461.
Vision Res. 1991;31(7-8):1143-57. doi: 10.1016/0042-6989(91)90040-c.
The striate cortical contribution to the surface pattern-reversal visual evoked potential (VEP) was investigated in awake monkeys during performance of a visual fixation task, by examining laminar profiles of VEP, current source density (CSD) and concomitant multiunit activity (MUA) in Area 17, recorded simultaneously at incremental depths using multicontact electrodes. Stimuli were black/white bar gratings centered on the fixation point. The typical surface pattern-reversal VEP over striate cortex consists of a prominent positivity peaking at 50-70 msec (P60), followed by a large negativity peaking at approx. 80 msec (N80), and then by a late broad positivity, peaking between 120 and 150 msec (P125). P60 is often preceded by a small negativity peaking at 45-55 msec (N50), and on rare occasions a small positivity (P40) is also observed. N50 is generated primarily by current sinks in Lamina 4C. P60 arises from large current sources in the supragranular laminae. N80 and P125 appear to be composite waveforms reflecting complex contributions from local activity and from activity occurring outside of the foveal/immediate parafoveal representation in Area 17. The basic physiologic sequence elicited by patterned stimulation is similar to that elicited by diffuse luminance or by electrical stimulation, but is characterized by more prominent supra- and infragranular activation. It is consistent with the cellular and synaptic anatomy of Area 17: initial activation of the thalamorecipient subdivisions of Lamina 4C, followed by activation of mid/upper Lamina 4 and of supra- and infragranular laminae. Our results suggest the possibility of differentiating synaptic stages and cellular processes reflected in the human VEP, based on homologies with simian VEP components.
在清醒的猴子执行视觉注视任务期间，通过检查17区中视觉诱发电位（VEP）、电流源密度（CSD）和伴随的多单位活动（MUA）的层状分布情况，利用多触点电极在递增深度同时记录，研究了纹状皮质对表面模式反转视觉诱发电位的贡献。刺激物是位于注视点中心的黑白条形光栅。纹状皮质上典型的表面模式反转VEP由一个在50 - 70毫秒达到峰值的明显正波（P60）组成，随后是一个在约80毫秒达到峰值的大负波（N80），接着是一个在120至150毫秒之间达到峰值的晚期宽正波（P125）。P60之前通常有一个在45 - 55毫秒达到峰值的小负波（N50），并且在极少数情况下还会观察到一个小正波（P40）。N50主要由4C层中的电流汇产生。P60来自颗粒上层中的大电流源。N80和P125似乎是复合波形，反映了局部活动以及17区中央凹/紧邻中央凹旁区域表征之外发生的活动的复杂贡献。模式刺激引发的基本生理序列与由漫射亮度或电刺激引发的序列相似，但特征是颗粒上和颗粒下的激活更为明显。这与17区的细胞和突触解剖结构一致：4C层的丘脑接受亚区首先被激活，随后是4层中/上部以及颗粒上和颗粒下层被激活。我们的结果表明，基于与猿猴VEP成分的同源性，有可能区分人类VEP中反映的突触阶段和细胞过程。
