Fig. 6: Contralesional neurons display dynamic alterations of spontaneous activity levels following traumatic brain injury.

a Scheme of functional in vivo imaging experiments investigating contralesional neurons using AAV-GCaMP6m. b Average projection of a representative field of view (FOV) showing neurons transduced with AAV-GCaMP6m in the contralesional hemisphere (green) and retrogradely transduced with retroAAV-CAG-tdtomato (red) at different time points following traumatic brain injury (B – baseline). Bottom: Calcium traces of example neurons marked within the FOV images. Scale bar equals 50 μm. c Fraction of active cells at baseline and two different time points following traumatic brain injury for callosal and non-callosal cells. n = 13 independent fields of views (663 non callosal and 139 callosal neurons) from six mice. Baseline (B) vs 10d: callosal neurons p = 0.029; non-callosal neurons p = 0.015, two-tailed t-test. 10d vs 42d: callosal neurons p = 0.027, non-callosal p = 0.047, two-tailed t-test. d Cumulative distributions of calcium transient frequencies at the indicated time points following traumatic brain injury. Note a shift in the distribution toward lower frequencies at 10d following lesion and a slight recovery at 42d. Baseline vs 10d: callosal neurons p = 0.013, non-callosal neurons p < 10–10, KS test). 10d vs 42d: callosal neurons p = 0.23, non-callosal neurons p = 0.012, KS test. Baseline vs 42d non-callosal p < 10-4, KS test. e Activity change between baseline and 42d in initially active non-callosal and callosal neurons. f Fraction of active cells at 42d dependent on the initial activity levels at baseline in non-callosal and callosal neurons (≥1 transient/min: ‘high’, <1 transient/min: ‘low’). Note that the initial activity levels determines the likelihood of remaining active at 42 days after the injury. Data analyzed with non-parametric bootstrapping of 10,000 iterations. Error bars represent the 95% confidence interval (CI). g Fate of non-callosal and callosal neurons active at baseline. h Activity history of non-callosal and callosal neurons active at 42d., *p < 0.05, **p < 0.01, ***p < 0.001. Source data are provided as a Source Data file.