Additional file 8: Figure S8. of Somato-dendritic decoupling as a novel mechanism for protracted cortical maturation

Optical changes driven by the imposed pipette tonicity. A–B: A schematic illustration of the experiments to confirm a whole-cell configuration based on the characteristic feature that, under whole-cell conditions, the properties of the pipette solution are imposed to the cytosol through dialysis. Here a hypotonic pipette solution was used to provide a driving force for the movement of ions from the cell interior to the pipette during dialysis (red arrow; panel A). Following dialysis (e.g. >3 min) the interior of the cell becomes like the pipette solution (i.e. hypotonic), thus leading to a crenation-like effect in cell shape as water moves out of the cell (panel A). Conversely, using a hypertonic pipette solution will result in the opposite effect; ions move into the cell and ultimately lead to cell swelling membrane dimpling (panel B). C: Representative examples of these types of responses, which were quite robust occurring in 100 % of cells tested. Under these conditions cells still failed to demonstrate action potential and rectifying currents. D: This response can be partially quantified using an ImageJ profile analysis where the grey value represents regions of high contrast (e.g. edges) from the DIC image region of interest (orange line; the coloured arrows correspond to the same spatial locations as in panel C). It should be mentioned that unlike the XY planes of the cell which are associated with the coverslip, changes could also be observed in the Z plane but were difficult to quantify. The colors correspond to the initial condition (green) and the dialyzed condition (orange) for both panels C and D. E: The summarized data represent the proportional change in cross-sectional distance of dormant cells for both the hypertonic (light grey; n = 6; t (5) = 4.28, one-sampled t test p = 0.0079) and hypotonic (dark grey; n = 5; t (4) = 10.51, one-sampled t test p = 0.0005) conditions. Note that volume increases non-linearly with distance. * denotes p < 0.05. Scale bar = 5 μm. (PDF 148 kb