Figure 1

Expression of 4R0N-tau augments the afterhyperpolarization in hippocampal CA1 pyramidal neurons. (Ai) Membrane current evoked by a step depolarization to + 10 mV (100 ms duration) and measured at the holding potential of − 50 mV. Current represents that underlying the medium and slow AHPs, with the current underlying the medium AHP shown at higher resolution in (Aii). Expression of 4R0N-tau produced a larger amplitude of current underlying both components of AHP (gray trace), when compared with current evoked in cells expressing only EGFP (black trace). (Aiii) Bar chart showing augmentation of the current underlying the medium AHP by expression of 4R0N-tau (mean ± s.e.m) (p < 0.0001). (Aiv) Expression of 4R0N-tau significantly augmented the amplitude of the current underlying the slow AHP (p = 0.00097) (EGFP n = 53, 4R0N-tau n = 33). (Bi,Ci) Membrane voltage traces showing AHP amplitude increases with action potential (AP) number (5–25 action potentials) in both EGFP-expressing (Bi) and 4R0N-tau-expressing (Ci) CA1 pyramidal neurons. (Bii,Cii) Voltage traces from (Bi,Ci) plotted on a log₁₀ time scale for greater clarity of the medium AHP and slow AHP profiles for a cell expressing EGFP alone (Bii) and for a cell expressing 4R0N-tau (Cii). The medium AHP is measured 100 ms after the last action potential, while the slow AHP was measured 1 s after the last AP. The increase in the medium (D) and slow (E) AHP components with increasing AP number is augmented in cells expressing 4R0N-tau, when compared with cells expressing EGFP alone. Two-way RM ANOVA with post-hoc LSD t-test. EGFP n = 58; 4R0N-tau n = 36; *p ≤ 0.05, **p ≤ 0.01.