Abstract
Neuronal responses of the primary visual cortex (V1) exhibit stimulus-size tuning property, and they are suppressed by stimulation with grating patches larger than their classical receptive field (CRF). Recently, it has been revealed that size-tuning property of V1 neurons is dependent on stimulus parameters, such as luminance contrast and spatial frequency. In this study, we examined the effect of temporal frequency (TF) of sinusoidal grating stimulus on size-tuning curves of cat V1 neurons. Our results showed that when the TF was higher than optimal, the strength of surround suppression became weak and CRF-size became larger, suggesting that V1 neurons summate visual information from wider region under high TF condition. We also tested the effect of changing stimulus-size on TF tuning curve. Corresponding to above results, large grating made peak and high cut-off of TF-tuning curve higher than those for small grating. Then we examined neuronal responses of the lateral geniculate nucleus (LGN), and obtained basically similar results to those of V1 neurons. These results suggest that neurons in early visual pathway change their spatial integration property according to TF of stimulus, in such a way that neurons integrate wide visual field for fast moving stimulus, whereas localized field for slow stimulus. [J Physiol Sci. 2006;56 Suppl:S176]
