Spatiotemporal frequency and direction sensitivities of human visual areas measured using fMRI
Spatiotemporal frequency and direction sensitivities of human visual areas measured using fMRI
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DOI：
10.1006/nimg.2000.0642
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发表时间：
2000-11-01
期刊：
影响因子：
5.7
通讯作者：
Greenlee, MW
中科院分区：
文献类型：
--
作者：
Singh, KD;Smith, AT;Greenlee, MW
我们利用功能磁共振成像(FMRI)研究了各视觉区域(V1-V5)的反应幅度随空间频率(SF)、时间频率(Tf)和单向运动与反相位闪烁的变化。使用视网膜定位图、功能磁共振成像和皮质平坦化技术相结合的方法在每个受试者中识别每个视觉区域。我们使用漂移(或反相位)正弦光栅作为刺激，参数变化SF在0.4到7周/度之间，Tf在0到18赫兹之间。对于每个实验，我们构建了每个视觉区域跨受试者平均的fMRI幅度调谐曲线。得到的调谐曲线与已知的猕猴视觉区域细胞的生理特性、先前的功能成像研究以及在V1的情况下，心理生理决定的空间和时间频率的对比敏感度函数是一致的。在V3A的情况下，获得的SF调谐函数更类似于在猕猴V3而不是猕猴V3A的单细胞研究中发现的。所有区域都显示出至少适度的定向运动相对于反相运动的偏好，其中V5表现出最大的偏好。视觉区域V1、V2、V3和V3A在一定的空间频率下表现出更高的方向敏感度，而Vp、V4和V5区域在较高的空间频率下具有最高的漂移与反相比率。(C)2000年学术出版社。
Using functional magnetic resonance imaging (fMRI) we have studied the variation in response magnitude, in each visual area (V1-V5), as a function of spatial frequency (SF), temporal frequency (TF) and unidirectional motion versus counterphase flicker. Each visual area was identified in each subject using a combination of retinotopic mapping fMRI and cortical flattening techniques. A drifting (or counterphasing) sinusoidal grating was used as the stimulus in a study in which we parametrically varied SF between 0.4 and 7 cycles/degree and TF between 0 and 18 Hz. For each experiment we constructed fMRI amplitude tuning curves, averaged across subjects, for each visual area. The tuning curves that resulted are consistent with the known physiological properties of cells in the corresponding macaque visual areas, previous functional imaging studies, and in the case of V1, the psychophysically determined contrast sensitivity functions for spatial and temporal frequency. In the case of V3A, the SF tuning functions obtained were more similar to those found in single cell studies of macaque V3 rather than macaque V3A All areas showed at least a moderate preference for directed versus counterphasing motion with V5 showing the largest preference. Visual areas V1, V2, V3, and V3A showed more direction sensitivity at law spatial frequencies, while VP, V4, and V5 had the highest drifting versus counterphasing ratios for higher spatial frequencies. (C) 2000 Academic Press.