Figure 2.

ET cells burst rhythmically, whereas PG cells exhibit burst of EPSPs. A, The left panel shows recordings from the same ET cell in cell-attached mode (bottom trace; spikes truncated because of membrane filtering during gigaohm seal recording) and whole-cell configuration (top trace; 1 min after rupturing the membrane). The frequency (∼3 Hz) and pattern of bursting were comparable in cell-attached and whole-cell modes. The right panel shows the morphology of the same ET cell. Note the highly branched dendritic tuft that ramifies throughout a single glomerulus. Scale bar, 100 μm. ONL, Olfactory nerve layer. B, Top traces, Current-clamp recordings show effects of steady hyperpolarizing or depolarizing current injection in a typical PG cell. At rest (0 pA), the cell receives spontaneous bursts of EPSCs and generates spikes infrequently, notably during bursts of EPSPs. The cell did not generate spike bursts after depolarizing or hyperpolarizing current injection. Reconstruction of the recorded cell at the left shows typical morphology of PG cell, including relatively small soma and one to three relatively thick primary dendritic shafts, which give rise to thinner branches ramifying within a subregion of a single glomerulus. Scale bar, 100 μm. Bottom traces, Voltage-clamp recording (holding potential, –60 mV) shows bursts of spontaneous EPSCs in the same PG cell; region enclosed in the box is shown at faster time scale at right.