Figure 4. Examples of associations between a respiration-synchronized discharge pattern and different types of membrane potential slow oscillations.

A) Examples of intracellular recordings with a respiration-synchronized discharge pattern that is associated (1) or not associated (2) with a membrane potential slow oscillation (MPSO). Top: intracellular recording with truncated action potentials; bottom: respiration signal with expiration (Expi) and inspiration (Inspi) separated by a dotted line. The gray circles indicate the signal transitions between inspiration and expiration. Insets: left inset: respiration-triggered histogram of action potentials; right insets: Fourier power spectrum plot of membrane potential (top) and respiration-triggered membrane potential average (bottom). The vertical dotted line indicates the inspiration/expiration transition. The up-point proportion is indicated in the right corner. B) Example of the emergence of MPSO with an intracellular excitability change. 1) At the resting membrane potential (RMP; no stabilizing injected current), NoMPSO was observed in association with an Sc pattern. 2) When hyperpolarized (in the H3 state, injected current: −0.2 nA), a positive intracellular oscillation (MPSO+) emerged in association with a null pattern. Top: intracellular recording with truncated action potentials; bottom: respiration signal with expiration (Expi) and inspiration (Inspi) separated by a dotted line. The gray circles indicate the signal transitions between inspiration and expiration. Insets: left inset: respiration-triggered histogram of action potentials; right insets: Fourier power spectrum plot of membrane potential (top) and respiration-triggered membrane potential average (bottom). The vertical dotted line indicates the inspiration/expiration transition. The up-point proportion is indicated in the right corner.