Bacon B A, Lepore F, Guillemot J P
Département de Psychologie, Université de Montréal, Canada.
Exp Brain Res. 2000 Oct;134(4):464-76. doi: 10.1007/s002210000482.
Single units in the posteromedial lateral suprasylvian area of the cat are known to be very sensitive to movement. A proportion of these cells can encode movement in depth, but it is unclear whether posteromedial lateral suprasylvian cells only rely upon motion cues to evaluate stimulus depth or whether they can also code for spatial cues. The present study aims at assessing the sensitivity to spatial disparity of binocular cells, in the postero-medial lateral suprasylvian area, in order to determine whether these units are tuned to positional depth cues. A total of 126 single cells located in the posteromedial lateral suprasylvian area of anesthetized, paralyzed cats were examined. As recordings were performed in the central visual field representation, receptive fields were small. A third of the receptive fields were surrounded by an inhibitory region and almost three-quarters of the cells were direction-selective. Most cells (110/114) were binocular, and a large proportion of single neurons responded to stimuli appearing on the fixation plane by increasing (tuned excitatory cells, 43%) or decreasing (tuned inhibitory cells, 14%) their response rate. A smaller proportion of cells increased their firing rate in response to crossed (near cells, 10%) or uncrossed (far cells, 6%) spatial disparities, hence demonstrating respective preference for stimuli presumably appearing in front of or behind the fixation plane. As compared to primary visual cortex, the proportion of disparity-sensitive cells in posteromedial lateral suprasylvian area is similar, but selectivity is significantly coarser. As the posteromedial lateral suprasylvian area can code for both spatial and temporal aspects of stimuli, this area might be involved in the spatiotemporal integration of depth cues, a process that may also participate in the control of accommodation and vergence.
已知猫的颞上沟后内侧区中的单个神经元对运动非常敏感。这些细胞中有一部分能够编码深度运动，但尚不清楚颞上沟后内侧区的细胞是仅依靠运动线索来评估刺激深度，还是也能够编码空间线索。本研究旨在评估颞上沟后内侧区双眼细胞对空间视差的敏感性，以确定这些神经元是否对位置深度线索进行了调谐。对126个位于麻醉、瘫痪猫的颞上沟后内侧区的单个细胞进行了检查。由于记录是在中央视野表征中进行的，因此感受野较小。三分之一的感受野被抑制区域包围，近四分之三的细胞具有方向选择性。大多数细胞（110/114）是双眼的，并且很大一部分单个神经元通过增加（调谐兴奋性细胞，43%）或降低（调谐抑制性细胞，14%）其反应率来对出现在固定平面上的刺激作出反应。较小比例的细胞在对交叉（近细胞，10%）或不交叉（远细胞，6%）空间视差作出反应时增加其放电率，因此分别表现出对可能出现在固定平面之前或之后的刺激的偏好。与初级视觉皮层相比，颞上沟后内侧区中视差敏感细胞的比例相似，但选择性明显更粗糙。由于颞上沟后内侧区能够对刺激的空间和时间方面进行编码，该区域可能参与深度线索的时空整合，这一过程也可能参与调节和集合的控制。
