Fig. 2. Effects of isoflurane on intracranial local field potentials (LFPs) recorded simultaneously in the primary somatosensory cortex (SI, black trace ) and in the ventroposterolateral thalamic nuclei (VPL, blue trace ). (A ) Raw LFP recordings representing a sample of 10 s of ongoing LFP activity recorded during the last 5 min before anesthesia induction (unaesthetized period) and during the last 5 min of each isoflurane concentration (0.8, 1.1, 1.4, and 1.7%). Visual inspection of the LFP traces revealed similar patterns of signal amplitude oscillations developed by the two recorded areas across the anesthesia stages. (B ) Correspondent power spectrogram of each SI trace from A . Spectrograms showed the different patterns of signal power across the frequency range analyzed, with the appearance of alternating periods of quiescence and high-frequency activity, at higher anesthetic depths. This is compatible with the burst suppression pattern observed on the LFP correspondent traces (A ).