Figure 9.

SPW‐Rs are terminated by hyperpolarization. (A) Top: cartoon of a microdrive and scheme of the electrode arrangement in the dorsal CA1 pyramidal layer for intracellular recording in freely moving mice. Bottom: intracellular filled and labeled pyramidal cell. (B) LFP trace (blue) showing two SPW‐R events (asterisks) and simultaneously recorded membrane potential (V _m, red). (C) Correlation between V _m ripple power (100–200 Hz) and postripple V _m as a function of time; red is mean; light red lines are SEM. (D) LFP ripple‐triggered average of post‐ripple V _m. Ripples with spikes: mean (red) and SEM (light red); ripples with no spikes: mean (dark green) and SEM (green); (E) LFP ripple‐triggered average of LFP and V _m at rest (−64 mV) and during two levels of negative current injection (resulting in −79 mV, −117 mV). (F) SPW‐R peak‐triggered average LFP, using three different thresholds (<3 SD, 3–5 SD and >5 SD of background power in the 100–200 Hz band). (G) Multiple unit firing during the corresponding three averages. Note ramp‐like elevation of multiple unit discharge preceding the SPW‐R and the decreased (below baseline) activity after the SPW‐R. For these analyses only isolated SPW‐Rs were selected. (H) Correlation between ripple current power (CSD) and the magnitude of post‐ripple negativity (“AHP”) in the CA1 pyramidal layer. Note that larger amplitude ripples are followed by larger post‐ripple negativity (as in F). A–E are reproduced from English et al. (2014). F–H are unpublished findings by Sullivan and Buzsáki.