Beckman Vision Center, University of California, San Francisco, San Francisco, California, USA.
Nat Neurosci. 2011 Nov 6;14(12):1574-80. doi: 10.1038/nn.2958.
The abundant concentration of cytochrome oxidase in patches or blobs of primate striate cortex has never been explained. Patches are thought to contain unoriented, color-opponent neurons. Lacking orientation selectivity, these cells might endow patches with high metabolic activity because they respond to all contours in visual scenes. To test this idea, we measured orientation tuning in layer 2/3 of macaque cortical area V1 using acutely implanted 100-electrode arrays. Each electrode recording site was identified and assigned to the patch or interpatch compartment. The mean orientation bandwidth of cells was 28.4° in patches and 25.8° in interpatches. Neurons in patches were indeed less orientation selective, but the difference was subtle, indicating that the processing of form and color is not strictly segregated in V1. The most conspicuous finding was that patch cells had a 49% greater overall firing rate. This global difference in neuronal responsiveness, rather than an absence of orientation tuning, may account for the rich mitochondrial enzyme activity that defines patches.
纹状皮层的斑块或小球中细胞色素氧化酶的丰富浓度从未得到解释。这些斑块被认为包含无定向、颜色对立的神经元。由于这些细胞对视觉场景中的所有轮廓都有反应，因此缺乏方向选择性，它们可能会使斑块具有高代谢活性。为了验证这一观点，我们使用急性植入的 100 电极阵列测量了猕猴大脑 V1 皮层区域 2/3 层的方位调谐。每个电极记录点都被识别并分配到斑块或斑块间隔区。斑块中细胞的平均方位带宽为 28.4°，而斑块间隔区为 25.8°。斑块中的神经元确实选择性较低，但差异很小，表明 V1 中颜色和形状的处理并未严格分离。最显著的发现是，斑块细胞的整体放电率增加了 49%。这种神经元反应的整体差异，而不是方位调谐的缺失，可能解释了定义斑块的丰富线粒体酶活性。
