Fig. 2.

Cellular properties of DACs. Resting spontaneous spike activities in 4 different cells provide examples of DACs that are nearly silent (A1), continuously active (B1), or exhibit steady discharge with intermixed bursts of spikes (C1) or periodic bursts (D). Resting membrane potentials (in mV) are indicated at left of each trace. The voltage responses evoked by constant current steps in the same cells are shown by traces in A2, B2, and C2, respectively. Negative current steps in A2 and B2 were 20, 30, and 40 pA. Periodic burst firing persists in the presence of a mixture of excitatory and inhibitory synaptic blockers: l-(+)-2-amino-4-phosphonobutyric acid (l-APB; 50 μM), AP5 (50 μM), CNQX (50 μM), picrotoxin (50 μM), and strychnine (1 μM). Labels at left of each recording identify the resting potential (in mV) relative to the voltage trace using the voltage scale provided.