Figure 4.

Dendritically localized sEPSPs are strongly attenuated during propagation to the soma but maintain a uniform shape. A, Schematic diagram showing the experimental layout. B, Average traces for the 15% most attenuated sEPSPs from three different cells. Traces normalized to the amplitude of the dendritic sEPSP (black) illustrating large attenuation of the somatic potential (gray) with increasing distance from the soma. C, The ratio of somatic to dendritic average amplitudes for the 15% most attenuated sEPSPs as a function of distance from the soma to the dendritic recording pipette. Black symbols represent recordings from lateral dendrites. Gray symbols represent recordings from medial dendrites. Dashed line indicates one phase exponential decay; λ = 68.0, CI 39.5–163.8 μm, plateau = −0.12, CI 39.53–163.80, R² = 0.77, n = 26, constrained to 0, 1. D, Representative average traces for the three cells shown in B with amplitudes normalized to 1 to illustrate shape differences. E, Difference in the time at midpoint of the sEPSP rise (at half-amplitude) between the dendritic and somatic recording sites for events shown in C. Dashed line indicates linear fit; slope = 0.00124 mV/μm, R² = −0.48, n = 24, constrained to 0, 0, velocity = 0.8, CI 0.7–1.0 m/s. F, Half-width ratio for sEPSPs shown in C. Dashed line indicates exponential growth; λ = 5907, CI 591–∞ μm, R² = −0.01, n = 23, constrained to 0, 1.