Research paper
EEG slow waves in traumatic brain injury: Convergent findings in mouse and man

https://doi.org/10.1016/j.nbscr.2016.06.001Get rights and content
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Highlights

  • Mild traumatic brain injury (mTBI) in mice is associated with more EEG slow waves during wakefulness.

  • Chronic mTBI in humans is associated with more EEG slow waves during wakefulness.

  • A novel metric of global coherence across multiple channels was calculated for EEG slow waves.

  • Global coherence of EEG slow waves was significantly correlated with severity of post-concussive symptoms.

  • Sleep EEG slow wave quantity and coherence may represent a sensitive marker of mTBI and post-concussive symptoms.

Abstract

Objective

Evidence from previous studies suggests that greater sleep pressure, in the form of EEG-based slow waves, accumulates in specific brain regions that are more active during prior waking experience. We sought to quantify the number and coherence of EEG slow waves in subjects with mild traumatic brain injury (mTBI).

Methods

We developed a method to automatically detect individual slow waves in each EEG channel, and validated this method using simulated EEG data. We then used this method to quantify EEG-based slow waves during sleep and wake states in both mouse and human subjects with mTBI. A modified coherence index that accounts for information from multiple channels was calculated as a measure of slow wave synchrony.

Results

Brain-injured mice showed significantly higher theta:alpha amplitude ratios and significantly more slow waves during spontaneous wakefulness and during prolonged sleep deprivation, compared to sham-injured control mice. Human subjects with mTBI showed significantly higher theta:beta amplitude ratios and significantly more EEG slow waves while awake compared to age-matched control subjects. We then quantified the global coherence index of slow waves across several EEG channels in human subjects. Individuals with mTBI showed significantly less EEG global coherence compared to control subjects while awake, but not during sleep. EEG global coherence was significantly correlated with severity of post-concussive symptoms (as assessed by the Neurobehavioral Symptom Inventory scale).

Conclusion and implications

Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms.

Keywords

Traumatic brain injury
Sleep
EEG
Slow waves
Coherence
Translational

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