Sample traces. A, Ten-second current traces are shown at three holding potentials. Current noise increased with depolarization. B, Ten-second voltage traces are shown for the same cell at the same potentials (controlled by adjusting the current). Voltage noise also increased with depolarization. The voltage traces are clearly low-pass filtered by the membrane. C, Occasional nonstationary events, such as those ∼14 and 20 sec, were removed from the traces. These likely corresponded to unblocked synaptic activity and often lasted for several seconds, although their appearance and behavior varied from cell to cell. D, For a typical PSD, power line interference (at 60 Hz and multiples) and an injected 0.5 pA, 250 Hz component (indicated by an arrow) are evident.