Separation effect of early visual cortex V1 under different crowding conditions: a transcranial magnetic stimulation...

The visual crowding makes it difficult to identify the patterns in peripheral vision, but the neural mechanism for this phenomenon is still unclear because of different opinions. To study the separation effect of early visual cortex V1 under different crowding conditions, single-pulse transcranial magnetic stimulation (TMS) is applied within the right V1. The experimental design includes two factors: TMS intensity (10%, 65%, and 90% of the phosphene threshold) and crowding conditions (high and low). The accuracy results show that there is a strong interaction between crowding and TMS conditions. When the TMS intensity is 65% or 90% of the phosphene threshold, more crowding will be perceived under the high crowding condition, and less crowding under the low crowding condition. We concluded that the high and the low crowding conditions can be separated by TMS. These results support the assumption that the crowding is related to V1 and occurs in the visual coding phase.