Figure 2.

Electrical conduction determining length constant. (A) Representative dual simultaneous intracellular recording illustrating V_m traces at Site 1 (V_m1) and Site 2 (V_m2) separated by 500 µm. Current pulses (±0.1–3 nA, 2 s each) were injected at Site 1 while V_m was recorded at Sites 1 and 2. (B) Plot of summary data (means ± SE) for current injected into Site 1 versus ΔV_m at Site 2. Black line: recordings at 500 µm separation (n= 15); slope by linear regression (R²= 1) represents conduction amplitude = 7.0 ± 0.7 mV·nA⁻¹ (n= 15). For single-point reference, conduction amplitude calculated for −1 nA current = 7.2 ± 0.6 mV·nA⁻¹. Grey line: recordings at 1500 µm separation (n= 8). (C) Conduction amplitude (ΔV_m2 in response to −1 nA current injection at Site 1) with increasing separation distance between Sites 1 and 2 (50 µm: 11.4 ± 0.4; 500 µm: 7.6 ± 0.6; 1000 µm: 5.7 ± 0.4; 1500 µm: 3.8 ± 0.4; 2000 µm: 3.2 ± 0.4 mV·nA⁻¹). Length constant (λ) = 1360 ± 100 µm calculated from monoexponential fit (R²= 0.99) to summary data (n= 8 for 50–1500 µm; n= 4 at 2000 µm).