Coincidence of binocular synaptic inputs quantified by subthreshold STRFs. A, Top left, Contralateral (blue) and ipsilateral (red) spatial RFs (outlined by dashed lines) of a binocular cell recorded in the pre-CP. Top right, Cumulative distribution of the onset latencies of contralateral or ipsilateral PSPs evoked by single pixel stimuli within RFs, with open circles indicating the averages. Bottom left, Nine consecutive time frames of contralateral or ipsilateral tRFs in 10 ms intervals; membrane potentials at 64 pixel positions are coded by gray intensities. The onset times of contralateral and ipsilateral tRFs are indicated by thick blue and red boxes, respectively. Bottom right, Change in the variance of membrane potentials at 64 positions (binned at 1 ms) over the time. Vertical blue and red lines, Onset times of contralateral and ipsilateral RFs, respectively. B, C, Same as A except binocular cells were examined in CP (B) and adult (C) mice. D, Summary of the mean onset latency measured from pixel-evoked PSPs (top) or tRFs (bottom). Filled circles with error bars: mean ± SD. E, Correlation plot of the ipsi–contra latency difference measured from pixel-PSPs and tRFs. Dashed line, Linear regression fit.