Foster K H, Gaska J P, Nagler M, Pollen D A
J Physiol. 1985 Aug;365:331-63. doi: 10.1113/jphysiol.1985.sp015776.
The spatial and temporal frequency selectivity of 148 neurones in the striate cortex, V1, and of 122 neurones in the second visual cortical area, V2, of the macaque monkey were studied using sine-wave gratings of suprathreshold contrast drifting over the receptive field at the preferred orientation and direction. Neurones in V1 and V2 were selective for different but partially overlapping ranges of the spatial frequency spectrum. At retinal eccentricities of 2-5 deg from the fovea, the spatial frequency preferences for neurones ranged from 0.5 to 8.0 cycles/deg in V1 and from 0.2 to 2.1 cycles/deg in V2 and were on average almost 2 octaves lower in V2 than in V1. Spatial frequency full band widths in the two cortical areas were in the range 0.8-3.0 octaves, with a mean value of 1.8 octaves, in the parafoveal representation of both V1 and V2, and 1.4 and 1.6 octaves respectively in the foveal representation of V1 and V2. Most neurones in V1 and some in V2 responded well at temporal frequencies up to 5.6-8.0 Hz before their responses dropped off at still higher frequencies. In V1, 68% of the neurones exhibited low-pass temporal tuning characteristics and 32% were very broadly tuned, with a mean temporal frequency full band width of 2.9 octaves. However, in V2 only 30% of the neurones showed low-pass temporal selectivity and 70% of the cells had bandpass temporal characteristics, with a mean full band width of 2.1 octaves. In V2 the minimal overlap of bandpass tuning curves across the temporal frequency spectrum suggests that there are at least two distinct bandpass temporal frequency mechanisms as well as neurones with low-pass temporal frequency tuning at each spatial frequency. A matrix of spatial and temporal frequency combinations was employed as stimuli for neurones with bandpass temporal frequency selectivity in both V1 and V2. The resultant spatio-temporal surfaces provided evidence that a neurone's preference for spatial frequency is essentially independent of the test temporal frequency; however, in V2 there was some tendency for temporal frequency peaks to shift slightly towards lower frequencies when non-optimum values of spatial frequency either above or below the preferred value were tested. Neurones with pronounced directional selectivity were encountered over a wide range of spatial frequencies, although in both cortical areas there was a tendency for an increased incidence of directional selectivity among neurones which were selective for lower spatial frequencies and higher temporal frequencies.
利用阈上对比度的正弦波光栅，以最佳方位和方向在猕猴初级视皮层（V1）的148个神经元以及第二视皮层区域（V2）的122个神经元的感受野上漂移，研究了它们的空间和时间频率选择性。V1和V2中的神经元对空间频谱的不同但部分重叠的范围具有选择性。在距中央凹2 - 5度的视网膜偏心率处，V1中神经元的空间频率偏好范围为0.5至8.0周/度，V2中为0.2至2.1周/度，V2中的平均空间频率偏好比V1中低近2个八度。在V1和V2的旁中央凹表征中，两个皮层区域的空间频率全带宽范围为0.8 - 3.0八度，平均值为1.8八度，在V1和V2的中央凹表征中分别为1.4和1.6八度。V1中的大多数神经元以及V2中的一些神经元在高达5.6 - 8.0 Hz的时间频率下反应良好，然后在更高频率时反应下降。在V1中，68%的神经元表现出低通时间调谐特性，32%的神经元调谐非常宽泛，平均时间频率全带宽为2.9八度。然而，在V2中只有30%的神经元表现出低通时间选择性，70%的细胞具有带通时间特性，平均全带宽为2.1八度。在V2中，带通调谐曲线在时间频谱上的最小重叠表明，在每个空间频率上至少存在两种不同的带通时间频率机制以及具有低通时间频率调谐的神经元。在V1和V2中，使用空间和时间频率组合矩阵作为具有带通时间频率选择性的神经元的刺激。所得的时空表面提供了证据，表明神经元对空间频率的偏好基本上与测试时间频率无关；然而，在V2中，当测试高于或低于偏好值的非最佳空间频率值时，时间频率峰值有略微向较低频率移动的趋势。在很宽的空间频率范围内都遇到了具有明显方向选择性的神经元，尽管在两个皮层区域中，在对较低空间频率和较高时间频率具有选择性的神经元中，方向选择性的发生率都有增加的趋势。
