Figure 1.

Simultaneous recording of MFs and CA3 GABAergic cells. A, Schematic of MF terminal–GABAergic cell pair recording, with a camera lucida drawing of a granule cell (black) back-filled through the recorded single bouton with biocytin; the dendrites of a GABAergic cell (gray) simultaneously recorded with the MF is also illustrated (traces: examples of MF and GABAergic cell discharges; scale bars, 100 μm; calibration: 20 mV, 200 ms). B, Photomicrographs of a single recorded MF from two different focal planes with a giant MF terminal (black arrowhead), filopodial extensions (black arrows), and small en passant boutons (white arrowheads). Scale bar, 5 μm. C, Differential interference contrast image of a giant MF terminal on the apical dendrite of a CA3 pyramidal cell (asterisk) before (left) and after (right) patching on the terminal. D, Onset delays (from the peak of presynaptic spike to the EPSC onset) for individual monosynaptic (dark bars) and polysynaptic (gray) pairs. E, Example traces from a monosynaptically coupled MF (presynaptic action potentials; top, black) to GABAergic cell pair (MF–EPSCs and failures; bottom, gray).