Mountcastle V B, Motter B C, Steinmetz M A, Sestokas A K
J Neurosci. 1987 Jul;7(7):2239-55. doi: 10.1523/JNEUROSCI.07-07-02239.1987.
The excitability of cortical neurons of prestriate area V4 and area PG of the inferior parietal lobule were examined using the method of single-neuron analysis in awake macaque monkeys. Levels of excitability were measured as the intensity of response to optimal visual stimuli placed in the most responsive region of the cell's receptive field. Physically and retinotopically identical stimuli were delivered during eye movement pauses under 3 conditions: during a no-task state in which the animal was awake and alert, but not receiving or expecting rewards or working in any task; between trials of the task state, the intertrial interval, while the animal awaited the appearance of a fixation target; and during the foreperiod of the task state, as the animal attentively fixated a small target light, waiting to detect its dimming in order to receive liquid reward. Experiments were carried out in 6 hemispheres of 4 monkeys; both V4 and PG were examined through the same chamber placements in 2 hemispheres. A total of 478 neurons in V4 and PG were identified as visual; quantitative studies were done on 146 in V4 and 54 in PG. We found in these experiments a common effect, a 3-4-fold facilitation of the responses of both V4 and PG visual neurons during the task state as compared to in the no-task state, and a differential effect, in that V4 neurons showed a similar 3-4-fold facilitation of responses to stimuli presented during the intertrial interval, whereas PG neuronal responses during this interval were similar to those evoked in the no-task state. We describe the functional properties of V4 neurons studied in the waking state. The findings are discussed in relation to the positions of these 2 areas in the occipitoparietal and occipitotemporal transcortical visual systems and to their respective roles in visuospatial perception and pattern recognition. They are also discussed with regard to the candidate neural mechanisms through which the changes in cortical neuronal excitability might be mediated.
采用单神经元分析方法，在清醒的猕猴身上检测了纹前区V4和顶下小叶PG区皮质神经元的兴奋性。兴奋性水平通过对置于细胞感受野最敏感区域的最佳视觉刺激的反应强度来衡量。在3种情况下，即在眼球运动暂停期间，给予物理和视网膜拓扑结构相同的刺激：在无任务状态下，动物清醒且警觉，但未接受或期待奖励，也未执行任何任务；在任务状态的试验间隔期间，即动物等待注视目标出现时；以及在任务状态的前周期，即动物专注地注视一个小目标光，等待检测其变暗以获得液体奖励时。实验在4只猴子的6个半球上进行；在2个半球中，通过相同的脑腔放置方式对V4和PG区进行了检测。在V4和PG区共识别出478个视觉神经元；对V4区的146个神经元和PG区的54个神经元进行了定量研究。我们在这些实验中发现了一个共同效应，即与无任务状态相比，任务状态下V4和PG区视觉神经元的反应增强了3 - 4倍；还发现了一个差异效应，即V4神经元对试验间隔期间呈现的刺激的反应也有类似的3 - 4倍增强，而在此间隔期间PG神经元的反应与无任务状态下诱发的反应相似。我们描述了在清醒状态下研究的V4神经元的功能特性。结合这两个区域在枕顶和枕颞跨皮质视觉系统中的位置，以及它们在视觉空间感知和模式识别中的各自作用，对这些发现进行了讨论。还讨论了可能介导皮质神经元兴奋性变化的候选神经机制。
