Spatio-temporal interaction in the parallel pathways of visual system

在初级视觉皮质(V1)，对经典感受野(CRF)中的刺激的反应受到CRF周围区(SRF)中的刺激的抑制调制。我们用持续时间为500ms的圆形正弦栅片和50ms的环形环作为CRF和SRF刺激的静态闪光，从空间频率(SF)调谐的角度研究了CATV1神经元对CRF刺激的反应和环绕抑制的时间动力学。在实验1(N=39)中，我们用最佳取向的栅片和不同的SFs来刺激CRF。随着反应时间的推移，首选SF由低到高变化。在实验2(N=48)中，CRF用最优取向的光栅加SF刺激，SRF用最优取向的光栅加不同SF的刺激开始-异步化(SOA)刺激。环绕抑制的SF调谐随反应时间而变化，有效的环绕抑制SF从低于CRF刺激的SF(CRF-SF)向接近CRF-SF的SF移动。通过改变SOA，我们考察了环境抑制对CRF反应的不同时相的影响。只有低SF(0.2c/deg)的SRF刺激可抑制CRF反应的初始时相。这些结果表明，环绕抑制涉及多种具有不同SF特征和时间特征的机制。

In the primary visual cortex (V1), a response to a stimulus in the classical receptive field (CRF) is suppressively modulated by a stimulus presented in the CRF surround (SRF). We examined the temporal dynamics of the response to CRF stimulation and the surround suppression in terms of spatial-frequency (SF) tuning of cat V1 neurons using stationary flashes of a circular sinusoidal grating patch (duration, 500ms) and an annulus (50ms) as CRF and SRF stimuli. In Experiment 1 (N=39), we stimulated CRF with grating patch of optimal orientation and varying SFs. The preferred SF shifted from low to high along time course of response. In Experiment 2 (N=48), CRF was stimulated with grating of optimal orientation and SF, while SRF was stimulated with grating of optimal orientation and varying SF sandstimulus-onset-asynchrony (SOA). SF tuning of surround suppression changed along time course of response, and effective SF of surround suppression shifted from the SF lower than that of CRF stimulus (CRF-SF) to that near CRF-SF. By changing SOA, we examined surround suppression on different temporal phases of CRF response. SRF stimulus only with low SF (<0.2c/deg) suppressed the initial phase of CRF response. These results suggest that multiple mechanisms with different SF- and temporal characteristics are involved in the surround suppression.