DETECTION OF POST-TRAUMATIC ABNORMALITIES OFSLEEP SPINDLES USING A NOVEL METHOD: LINKING BLAST-INDUCED TBI TO SLEEP DISORDERS AND SEIZURE SUSCEPTIBILITY IN A MOUSE MODEL

Blast-induced traumatic brain injury (bTBI) accounts for one-third of traumatic brain injuries (TBI) in soldiers, with chronic effects largely unknown. Electroencephalogram (EEG) signal changes may help predict outcomes like sleep disorders and post-traumatic epilepsy (PTE), which have been reported in rodent bTBI models. Modification of sleep spindles (SSPs), crucial thalamus-cortical signal for sleep transitions, have been linked to PTE and sleep disorders in non-blast TBI, but variability in detection methods affects findings. This study uses an improved SSPs detection algorithm to aim a more rigorous analysis of SSPs characteristics, necessary to understand the sleep disorders and seizure risk 1-month post-bTBI in mice. Following either bTBI or sham (non-blast) treatment, mice underwent a 1-week video-EEG recording, with pentylenetetrazol (PTZ) administered at the end to assess seizure susceptibility. Increased NREM sleep during dark period (hypersomnia) was observed on the first day of recording and a slight reduction in REM sleep was present over the week in both groups, anticipated in bTBI compared to sham. Seizure susceptibility showed no group difference. SSPs density did not differ, but bTBI showed a reduction of SSPs in higher amplitude and frequency range compared to sham. A specific SSP profile correlated with increased seizure susceptibility, though not with REM reduction nor bTBI itself, was identified. In conclusion, video-EEG recording may induce stress, shown by REM reduction in both groups. bTBI appears to increase fragility to stress, likely due to SSPs alterations, both under acute (e.g., first day in new housing) and chronic stress, manifesting as hypersomnia and earlier REM reduction respectively. EEG electrode implantation surgery might also contribute to increased seizure susceptibility. Although the SSP profile is more associated with seizure susceptibility than with bTBI itself, SSP distribution remains altered in bTBI compared to sham reflecting a possible modification of thalamo-cortical connectivity. Further research is needed to confirm SSPs alterations' origins in bTBI.