Fig. 3: Recording of individual neuronal action potentials in the cortex and thalamus of freely moving rats.

a Rat brain coronal section at bregma −3.6 mm (reproduced with permission from Paxinos & Watson Rat Brain Atlas⁹¹) indicating target locations of primary somatosensory trunk cortical (S1Tr) and ventrobasal thalamic (VB) electrode arrays. b Example principal component values of waveforms from simultaneously recorded cortical neurons (left) and sample raw broadband (1.1 Hz–7.6 kHz) voltage traces from a 16 channel array (right) from which neuron action potentials were extracted. Recording shows data during a non-seizure baseline period. PC7 and PC10 represent the first principal components from two channels in this example that show clear separation between clusters. c Single channel signal from same session as b but at a different time, during a transition from baseline waking to seizure state (see also part d). High-pass filtering by subtraction of median values with a 10-sample window shows identifiable action potential spike waveforms (negative deflections oriented downwards). d Raw (unfiltered) single channel data temporally aligned with trace c enables visualization of baseline waking state and spike-wave seizure activity, including action potential waveforms (red traces on insets).