Katholieke Universiteit Leuven, O&N 2, Laboratorium voor Neuro- en Psychofysiologie, Herestraat 49, Bus 1021, 3000 Leuven, Belgium.
J Neurophysiol. 2012 Sep;108(5):1392-402. doi: 10.1152/jn.00323.2012. Epub 2012 Jun 6.
Macaque frontal eye fields (FEF) and the lateral intraparietal area (LIP) are high-level oculomotor control centers that have been implicated in the allocation of spatial attention. Electrical microstimulation of macaque FEF elicits functional magnetic resonance imaging (fMRI) activations in area LIP, but no study has yet investigated the effect of FEF microstimulation on LIP at the single-cell or local field potential (LFP) level. We recorded spiking and LFP activity in area LIP during weak, subthreshold microstimulation of the FEF in a delayed-saccade task. FEF microstimulation caused a highly time- and frequency-specific, task-dependent increase in gamma power in retinotopically corresponding sites in LIP: FEF microstimulation produced a significant increase in LIP gamma power when a saccade target appeared and remained present in the LIP receptive field (RF), whereas less specific increases in alpha power were evoked by FEF microstimulation for saccades directed away from the RF. Stimulating FEF with weak currents had no effect on LIP spike rates or on the gamma power during memory saccades or passive fixation. These results provide the first evidence for task-dependent modulations of LFPs in LIP caused by top-down stimulation of FEF. Since the allocation and disengagement of spatial attention in visual cortex have been associated with increases in gamma and alpha power, respectively, the effects of FEF microstimulation on LIP are consistent with the known effects of spatial attention.
猕猴额眼区（FEF）和外侧顶内区（LIP）是高级眼球运动控制中枢，与空间注意力的分配有关。猕猴 FEF 的电微刺激会在 LIP 区引发功能磁共振成像（fMRI）激活，但尚无研究调查 FEF 微刺激对 LIP 的单细胞或局部场电位（LFP）水平的影响。我们在延迟眼跳任务中记录了 LIP 区的放电和 LFP 活动，同时对 FEF 进行了弱阈下微刺激。FEF 微刺激导致 LIP 中与视场对应部位的时间和频率特异性、任务依赖性的伽马功率增加：当眼跳目标出现在 LIP 感受野（RF）中并保持存在时，FEF 微刺激会显著增加 LIP 伽马功率，而对于远离 RF 的眼跳，FEF 微刺激会引起较小的 alpha 功率特异性增加。用弱电流刺激 FEF 对 LIP 尖峰率或记忆眼跳或被动注视期间的伽马功率没有影响。这些结果首次提供了证据，证明 FEF 的自上而下刺激会导致 LIP 中的 LFPs 产生任务依赖性调制。由于视觉皮层中空间注意力的分配和脱离分别与伽马和阿尔法功率的增加有关，因此 FEF 微刺激对 LIP 的影响与已知的空间注意力效应一致。
