Figure 1
Repeated in vivo two-photon imaging revealed S1 activity changes of adult mice after tSCI. (A) The ___location of hindlimb S1 area (HL-S1, yellow regions) was identified by applying electrical stimulation (0.2 mA and 200 μs) to the hind paw and recording cortical sensory evoked potentials in vivo (n = 4 mice). Each dot on the right cortical surface corresponds to a recording trace on the right. The distances between neighboring traces were 1 mm. A rectangular HL-S1 area was found to span 1.5–2 mm laterally and 2.5–3 mm in an anterolateral and posteromedial direction, with the medial border being ~1 mm lateral to the midline and the longitudinal center being ~1 mm posterior to the bregma. The mouse brain image was created with Allen Mouse Brain Atlas using Brain Explorer® 2 (©2014 Allen Institute for Brain Science. Allen Mouse Brain Atlas: http://mouse.brain-map.org/). (B) Average projections of the same regions of cortical layer II/III GCaMP6-expressing neurons at different time points after sham (top) and tSCI (bottom) surgery. (C) ΔF/F traces of calcium transients of neurons of sham and tSCI groups that correspond to the color-circled neurons in (A). (D) Changes in mean integrated fluorescence of the tSCI and sham groups indicate a loss of neuronal activity at 6 hours post-tSCI followed by recovery, suggesting homeostatic regulation of activity after tSCI in vivo (n = 7 mice in each group). (E) There is a similar pattern of change when the ratios of active neurons are quantified and compared. However, the ratio of active neurons in tSCI group at 48 hours was significantly higher than that of the sham group and the baseline of the tSCI group. For graphs (D and E), repeated measure ANOVA was followed by Bonferroni test. *p < 0.05 and ***p < 0.001 when compared with the baseline of the tSCI group; #p < 0.05 and ###p < 0.001 when compared between sham and tSCI groups at corresponding time points.
