Premereur Elsie, Vanduffel Wim, Janssen Peter
KU Leuven.
J Cogn Neurosci. 2014 Aug;26(8):1672-84. doi: 10.1162/jocn_a_00591. Epub 2014 Feb 24.
The macaque FEFs and the lateral intraparietal area (LIP) are high-level cortical areas involved in both spatial attention and oculomotor behavior. Stimulating FEF at a level below the threshold for evoking saccades increases fMRI activity and gamma power in area LIP, but the precise effect exerted by the FEF on LIP neurons is unknown. In our study, we recorded LIP single-unit activity during a visually guided saccade task with a peripherally presented go signal during microstimulation of FEF. We found that FEF microstimulation increased the LIP spike rate immediately after the highly salient go signal inside the LIP receptive field when both target and go signal were presented inside the receptive field, and no other possible go cues were present on the screen. The effect of FEF microstimulation on the LIP response was positive until at least 800 msec after microstimulation had ceased, but reversed for longer trial durations. Therefore, FEF microstimulation can modulate the LIP spike rate only when attention is selectively directed toward the stimulated location. These results provide the first direct evidence for LIP spike rate modulations caused by FEF microstimulation, thus showing that FEF activity can be the source of top-down control of area LIP.
猕猴的额眼区（FEF）和顶内沟外侧区（LIP）是参与空间注意力和眼球运动行为的高级皮质区域。在低于诱发扫视阈值的水平刺激FEF会增加LIP区域的功能磁共振成像（fMRI）活动和伽马功率，但FEF对LIP神经元的确切作用尚不清楚。在我们的研究中，我们在对FEF进行微刺激期间，于视觉引导的扫视任务中记录LIP的单神经元活动，该任务中有一个外周呈现的启动信号。我们发现，当目标和启动信号都出现在LIP感受野内且屏幕上没有其他可能的启动线索时，在LIP感受野内出现高度显著的启动信号后，FEF微刺激会立即提高LIP的放电率。FEF微刺激对LIP反应的影响在微刺激停止后至少800毫秒内是正向的，但在更长的试验持续时间内则会逆转。因此，只有当注意力选择性地指向受刺激位置时，FEF微刺激才能调节LIP的放电率。这些结果为FEF微刺激引起的LIP放电率调制提供了首个直接证据，从而表明FEF活动可能是LIP区域自上而下控制的来源。
