Platt M L, Glimcher P W
Center for Neural Science, New York University, NY 10003, USA.
Exp Brain Res. 1998 Jul;121(1):65-75. doi: 10.1007/s002210050438.
The activity of each of 99 intraparietal neurons was studied in three awake-behaving rhesus monkeys (Macaca mulatta) while subjects performed 100-900 delayed saccade trials. On each trial, a saccadic target was presented at one location selected randomly from a grid of 441 locations spanning 40 degrees of horizontal and vertical visual space. Individual neurons in our population were sensitive to both the direction and amplitude of saccades. Response fields, which plotted firing rate as a function of the horizontal and vertical amplitude of movements for each neuron, were characterized by a Cartesian two-dimensional gaussian model. The goodness-of-fit of these gaussian models was tested by: (1) comparing observed responses with predicted responses for each movement; and (2) by computing the percentage of variance explained by each model. Cartesian Gaussian models provided a good fit to the response fields of most neurons. Across our population, the Gaussian fit to the response field of each neuron accounted for more of the variance in neuronal activity when the data were plotted with regard to the horizontal and vertical amplitude of the saccade than when the same data were plotted with regard to the position of the saccadic target. The Gaussian functions were used to estimate the eccentricity and spatial tuning breadth of each neuronal response field. Modal response field radius was less than 5 degrees, whereas mean response field radius was about 10 degrees. Linear regression analysis demonstrated that response field eccentricity accounted for less than 30% of the variance in response field radius. Analysis of the horizontal distribution of response field centers showed an approximately normal distribution around central fixation. Most histologically recovered neurons were located on the lateral bank of the intraparietal sulcus, although a small number of saccade-related neurons were recorded from Brodmann's area 5 on the medial bank of the intraparietal sulcus.
在三只清醒行为的恒河猴（猕猴）执行100 - 900次延迟扫视试验时，研究了99个顶内神经元中每个神经元的活动。在每次试验中，从跨越40度水平和垂直视觉空间的441个位置的网格中随机选择一个位置呈现扫视目标。我们研究群体中的单个神经元对扫视的方向和幅度均敏感。响应域将每个神经元的放电率绘制为运动的水平和垂直幅度的函数，其特征由笛卡尔二维高斯模型描述。通过以下方式测试这些高斯模型的拟合优度：（1）比较每个运动的观察响应与预测响应；（2）计算每个模型解释的方差百分比。笛卡尔高斯模型对大多数神经元的响应域拟合良好。在我们的研究群体中，当根据扫视的水平和垂直幅度绘制数据时，每个神经元响应域的高斯拟合比根据扫视目标的位置绘制相同数据时能解释更多神经元活动的方差。高斯函数用于估计每个神经元响应域的偏心率和空间调谐宽度。模态响应域半径小于5度，而平均响应域半径约为10度。线性回归分析表明，响应域偏心率占响应域半径方差的比例不到30%。响应域中心的水平分布分析显示，围绕中央注视点呈近似正态分布。大多数组织学恢复的神经元位于顶内沟的外侧壁，尽管在内侧壁的布罗德曼5区记录到少量与扫视相关的神经元。
