Morrone M C, Di Stefano M, Burr D C
J Neurophysiol. 1986 Oct;56(4):969-86. doi: 10.1152/jn.1986.56.4.969.
Neurons in the posteromedial lateral suprasylvian cortex (PMLS) of cats were recorded extracellularly to investigate their response to stimulation by bars and by sinusoidal gratings. Two general types of cells were identified: those that modulated in synchrony with the passage of drifting bars and gratings and those that responded with an unmodulated increase in discharge. Both types responded to contrast reversed gratings with a modulation of activity: the cells that modulated to drifting gratings modulated to the first harmonic of contrast reversed gratings (at appropriate spatial phase and frequency), whereas those that did not modulate to drifting gratings always modulated to the second harmonic of contrast reversed gratings. No cell had a clear null point. Nearly all cells were selective for spatial frequency. The preferred frequency ranged from 0.1 to 1 cycles per degree (cpd), and selectivity bandwidths (full width at half height) were around two octaves. Preferred spatial frequency was not correlated with receptive field size, but bandwidth and receptive field size were positively correlated. Preferred spatial frequency decreased with eccentricity, at about 0.05 octaves/deg. The response of all cells increased as a function of grating contrast up to a saturation level. The contrast threshold for response to a grating of optimal parameters was approximately 1% for most cells and the saturation contrast approximately 10%. The contrast gain was approximately 25 spikes/s per log unit of contrast. All cells were tuned for temporal frequency, preferring frequencies from approximately 3 to 10 Hz, with a selectivity bandwidth approximately 2 octaves. For some cells, the spatial selectivity did not depend on the temporal frequency and vice versa. Others were spatiotemporally coupled, with the preferred temporal frequency being lower at high than at low spatial frequencies, and the preferred spatial frequency lower at high than at low temporal frequencies. Previous results showing broad velocity tuning to a bar were replicated and found to be predictable from the combined spatial and temporal tuning of PMLS cells and the Fourier spectrum of a bar. Preferred temporal frequency steadily decreased with eccentricity, at 0.025 octaves/deg. The results for PMLS cells are compared with those of other visual areas. Acuity and spatial preference and selectivity bandwidth is comparable to all areas except area 17, where they are a factor of about two higher. Temporal selectivity in PMLS is as fine as observed in other areas. The possibility that PMLS cells may be involved with motion detection and detection of motion in depth is discussed.
对猫的后内侧外侧上薛氏回皮质（PMLS）中的神经元进行细胞外记录，以研究它们对条形和正弦光栅刺激的反应。识别出两种一般类型的细胞：一类与漂移的条形和光栅的通过同步调制，另一类以放电的非调制增加做出反应。这两种类型的细胞对对比度反转的光栅都有活动调制反应：对漂移光栅进行调制的细胞对对比度反转光栅的基波进行调制（在适当的空间相位和频率下），而对漂移光栅不进行调制的细胞总是对对比度反转光栅的二次谐波进行调制。没有细胞有明显的零点。几乎所有细胞对空间频率都有选择性。偏好频率范围为每度0.1至1周（cpd），选择性带宽（半高全宽）约为两个八度。偏好空间频率与感受野大小无关，但带宽与感受野大小呈正相关。偏好空间频率随离心率降低，约为0.05八度/度。所有细胞的反应随光栅对比度增加，直至达到饱和水平。对于大多数细胞，对最佳参数光栅反应的对比度阈值约为1%，饱和对比度约为10%。对比度增益约为每对数单位对比度25个脉冲/秒。所有细胞都对时间频率进行调谐，偏好频率约为3至10赫兹，选择性带宽约为2个八度。对于一些细胞，空间选择性不依赖于时间频率，反之亦然。其他细胞是时空耦合的，在高空间频率下偏好时间频率低于低空间频率，在高时间频率下偏好空间频率低于低时间频率。先前显示对条形有广泛速度调谐的结果得到重复，并发现可根据PMLS细胞的组合空间和时间调谐以及条形的傅里叶频谱进行预测。偏好时间频率随离心率稳定降低，为0.025八度/度。将PMLS细胞的结果与其他视觉区域的结果进行比较。敏锐度、空间偏好和选择性带宽与除17区以外的所有区域相当，在17区它们大约高两倍。PMLS中的时间选择性与其他区域观察到的一样精细。讨论了PMLS细胞可能参与运动检测和深度运动检测的可能性。
