(

*A*) Noise covariance after spatial whitening. Subpanels: spacetime covariance

between the central channel and its neighbors as a function of

, for various fixed

(colored curves). Central panel (dotted line): the function

. (The various

lines and the dotted line are too similar to discriminate visually.) Horizontal axes:

in

; Vertical axes:

in

. (

*B*)

*Blue curve*, Semilog plot of the one point marginal probability density function of decorrelated noise samples.

*Red curve*, same quantity, evaluated on residuals after spikes have been removed from spike events.

*Dotted curve*, The Gaussian chosen to represent this distribution. (

*C*)

*Green*, detail of the same template waveform shown in .

*Red*, pointwise mean of the residuals after the fit spike is subtracted from 4,906 one-spike events of this type is nearly flat. This validates our assumption that spikes vary only in overall amplitude, and that noise is independent of spiking.

*Blue*, pointwise standard deviation of the residuals, again evidence that only noise remains after fitting and subtracting spikes. (

*D*,

*top*) Histogram of fit values of the scale factor

for a template with peak amplitude

(well above noise) obtained without a prior on

, superposed with a Gaussian of the same mean and variance. (

*D*,

*bottom*) Similar histogram for a low amplitude template. A secondary bump appears, due to noise-fits, but is well separated from the main peak; a cutoff is shown as a dashed green line. The superposed Gaussian has mean and variance computed from the part of the empirical distribution lying above the cutoff.

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