Fig 2.

Generalised slowing of EEG and disrupted functional connectivity after lipopolysaccharide injection. (a) Representative time-domain EEG signals during the pre-injection baseline hour (left) and 2 h post-injection (right) are shown for animals that received either a saline ‘vehicle’ (top) or 25 μg kg⁻¹ ‘low’ LPS injection (bottom). Traces were selected based on having mean SWA values approximately equal to the mean SWA over the entire hour. (b) The time series of SWA (2–4 Hz) normalised to mean spectral power (2–80 Hz) are shown for the different LPS doses. Symbols represent the mean percent change in SWA from baseline across all animals at each LPS dose at each recording hour. Error bars represent plus or minus standard error of the mean. (c) Time series of alpha band (13–20 Hz) anterior-posterior wPLI, a measure of functional connectivity. (d) The time series of movement for each LPS dose is shown. Symbols represent the mean percent change in movement from baseline across all animals at each dose of LPS at each recording hour. Error bars represent plus or minus standard error of the mean. (e) Example EEG power spectra separated according to movement magnitude. Power spectra were calculated in overlapping 4-s windows and aligned with movement epochs, then data were binned into quiescence (i.e. zero movement, left), lower quartile movement (middle), or upper quartile movement (right), and averaged. Pre-injection spectra (‘Baseline’) and average spectra of 1–3 h post-injection (‘Peak’), averaged across four EEG channels, are shown from animals that received either vehicle (top) or a 25 μg kg⁻¹ ‘low’ dose of LPS (bottom). LPS, lipopolysaccharide; movt, movement; SWA, slow wave activity; VEH, vehicle; wPLI, weighted phase lag index.