Fig. 1: Hemispheric differences in the maturation of thalamocortical input to the ACx.

a Connected bilateral TC slice preparation developed to study the maturation of the Left and Right ACx in the same animal. b Experimental set-up for VSD imaging. c Picture of a connected TC slice stimulated in the MGBv with ACx labeled where voltage changes were measured. d Movie frames (4 ms rate) for Left and Right ACx TC responses; first frame: first movie frame determined to show a significant TC response (see “Methods” section). e Cumulative binned depths of responsive locations for pixels in the upper quartile (>75th percentile) of signal magnitude for the first frame. Left ACx: blue, Right ACx: red; mean: solid lines, 95% confidence intervals: dotted lines. Circles indicate 25th, 50th (median), and 75th percentiles of the population average and S.E.M. There was no significant difference in the youngest group <P14 (Left panel, unpaired Welch’s t-test, Holm–Šídák method of correction for multiple comparisons; n = 9 and 7 slices for Left and Right ACx, respectively). A significant difference between the Left and Right ACx was observed at P14-16 (middle panel: 25th percentile p = 0.00107, 50th percentile p = 0.000939, 75th percentile p = 0.0041; n = 7 and 6, unpaired Welch’s t-test, Holm–Šídák correction). There was no significant difference in the oldest group (>P16, right panel, n = 9 and 5; unpaired Welch’s t-test, Holm–Šídák correction). Within a hemisphere, filled circles indicate a statistically significant change from the youngest age group (empty circles). See Supplementary Table 1 for within-hemisphere statistical test results. f Centroid of response calculated for the first frame across age and hemisphere groups. The centroid was not significantly different for ages <P14 nor >P16 (unpaired Welch’s t-test, Holm–Šídák correction; for <P14 n = 9 and 7; for >P16 n = 9 and 5). The only significant difference in centroid response between the Left and Right ACx occurred at ages P14–16 (p = 0.000747, n = 7 and 6; unpaired Welch’s t-test, Holm–Šídák correction; See Supplementary Table 1 for between-hemisphere statistical tests for these data). Filled circles and empty circles as in e. g population-averaged contour plots reporting the spatial distribution of thalamic input response latency. Data are presented as mean values ± SEM. All statistical tests performed were two-sided.