Figure 2.

UP and DOWN states in mitral cells require glutamatergic transmission. A, B, Absence of correlation between the mean membrane potential of individual MCs and UP state features (frequency and amplitude). Measurements were performed in MC recordings without current injection. C, Example of an MC recording in the voltage-clamp configuration at the reversal potential for chloride. Note the slow (inward) excitatory currents, likely corresponding to barrages of EPSCs, the frequency of which is similar to that of UP states (0.15 ± 0.06 Hz, n = 5). D, Treatment with kynurenic acid (2 mm), a blocker of ionotropic glutamate receptors, reversibly abolishes UP states generation. Periods indicated by red bars in the top trace are enlarged below. Note that action potentials have been truncated for clarity.