The name is absent

20

^σ2W = λΓ-Γ∑⅛W^^rW>²              <²'³>

^{γv - 1} x=l

with y_x(t), the difference between two successive traces, defined by:

Ух ~^ Ух+1

2

and the mean of differences calculated by:

^κ<¹> = ⅛ⁱ>

Traces that had spurious transient noise, caused by either temporary membrane break-
down, external electrical interference, or other causes needed to be removed from the en-
semble in order to generate a reliable estimate of the variance. If a minority of traces needed
to be removed, and the effect of rundown was small over the ensemble, then the variance
estimate according to equation 2.3 was reliable. Typically, traces which had 0.1% of their
points 3 or more standard deviations from the mean were removed. All results in this paper
are reported as mean ± SEM unless otherwise indicated.

After acquisition at IOkHz and filtering with a Iowpass Bessel filter at 4kHz, data were im-
ported into Igor Pro for processing, and digitally filtered to 400 Hz with a Gaussian weighted
FIR filter. This additional filtering step allowed us to increase the signal to noise ratio of our
recordings by reducing broad spectrum background noise fluctuations. Theoretical consid-
erations dictate that the filter time constant should be no greater than 10 times the activation
time constant of the recorded channels [4]. HCN channels were seen to transition with a

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