The figure shows simultaneous multi-unit activity (MUA; 300 Hz–3 kHz, 500th order FIR bandpass filter, black traces) and ‘micro’ EEG (uEEG; <50 Hz low-pass filter, grey trace). The activity in the bottom channel joins the seizure several seconds after the top channel, and shows MUA during the penumbral, tonic and clonic phases of the seizure. Note that the two MUA recordings are highly synchronized during the clonic phase, but at no other time. The penumbral phase clearly demonstrates dissociation between MUA and EEG (Schevon CA, McKhann G, Goodman RR, Yuste R, Emerson RG, Trevelyan AJ unpublished results; for details see ).