Figure 1.

Theta-rhythmical (5 Hz) EC/DG-input highly effectively generates neuronal activity flow through the hippocampus. (A–C) Experimental arrangement and protocol used for the investigations shown in (D–K). The experiments with 1 Hz EC/DG-input (N = 9 slices/6 mice) and 20 Hz EC/DG-input (N = 11 slices/6 mice) shown in (J and K) were performed in separate sets of slices. (B,D,F,I) Illustration and outcome of a representative experiment. Open triangles in (D) symbolize an interruption of VSDI for 4.34 s. (E) Quantification of neuronal activities in hippocampal subregions (N = 9 slices/5 mice). (G,I) Characteristics of the 5 Hz neuronal activities depicted and quantified in (D–F). (H) Bath application of the AMPA/kainate receptor blocker NBQX (5 μM) and the NMDA receptor antagonist APV (50 μM) to slices fully inhibited neuronal activity in the hippocampus. (J,K) Quantification of CA1 and DG neuronal activities resulting from 0.2, 1, 5, and 20 Hz EC/DG-input. (D,I) Stimulus artifacts in FPR traces were truncated for clarity. Abbreviations: ΔF/F, fractional change in fluorescence; F, imaging frame (number and time specification relative to stimulation pulse); FP(R), field potential (recording); HTC, hippocampal trisynaptic circuit; MF, mossy fiber; PS, population spike; ROI, region of interest; SC, Schaffer collateral; SL, stratum lucidum; SR, stratum radiatum; Stim, extracellular electrical stimulation; TA, temporoammonic pathway.