Alpha desynchronization/synchronization during working memory testing is compromised in acute mild traumatic brain injury (mTBI)

Abstract

Diagnosing and monitoring recovery of patients with mild traumatic brain injury (mTBI) is challenging because of the lack of objective, quantitative measures. Diagnosis is based on description of injuries often not witnessed, subtle neurocognitive symptoms, and neuropsychological testing. Since working memory (WM) is at the center of cognitive functions impaired in mTBI, this study was designed to define objective quantitative electroencephalographic (qEEG) measures of WM processing that may correlate with cognitive changes associated with acute mTBI. First-time mTBI patients and mild peripheral (limb) trauma controls without head injury were recruited from the emergency department. WM was assessed by a continuous performance task (N-back). EEG recordings were obtained during N-back testing on three occasions: within five days, two weeks, and one month after injury. Compared with controls, mTBI patients showed abnormal induced and evoked alpha activity including event-related desynchronization (ERD) and synchronization (ERS). For induced alpha power, TBI patients had excessive frontal ERD on their first and third visit. For evoked alpha, mTBI patients had lower parietal ERD/ERS at the second and third visits. These exploratory qEEG findings offer new and non-invasive candidate measures to characterize the evolution of injury over the first month, with potential to provide much-needed objective measures of brain dysfunction to diagnose and monitor the consequences of mTBI.

Compromised Behavior and Gamma Power During Working Memory in Cognitively Healthy Individuals With Abnormal CSF Amyloid/Tau

“…The brain cognitive challenge, or N-back WM test (N = 0, 2 that reflect the load conditions of the task), was administered using E-prime software (Psychology Software Tools, Inc., Sharpsburg PA) on a Dell Precision T5610 with a 20" screen. Procedures were described previously (Arakaki et al, 2018(Arakaki et al, , 2019. Participants were comfortably seated before a computer screen and were instructed, practiced for 2-3 min, and were then tested for 0-back, then for 2-back.…”

“…We performed group comparisons on participant baseline characteristics using two-sided t-tests or Fisher's exact test. For each participant, we averaged the total gamma power from all sensors and the gamma power from each sensor for each of the following 6 regions (Lianyang et al, 2016;Arakaki et al, 2018): frontal or F (Fz, F3, F4), central or C (Cz, C3, C4), parietal or P (Pz, P3, P4), left temporal or LT (F7, T3, T5), right temporal or RT (F8, T4, T6), and occipital or O (O1, O2) (demonstrated in the results section). We compared gamma power between two groups (PAT, NAT).…”

“…Online EEG data were collected during resting or the WM challenge as previously described (Arakaki et al, 2018). We placed a 21-sensor, dry electrode system (Quasar Wearable Sensing, DSI-24, San Diego, CA) approximately at locations at the international 10-20 system (Fp1, Fp2, F7, F3, Fz, F4, F8, T3, C3, Cz, C4, T4, T5, P3, Pz, P4, T6, O1, O2, M1, and M2).…”

“…Preprocessing steps included epoching, filtering, re-referencing, large artifact removal, and time-frequency analysis. Preprocessing and time-frequency (TF) analyses were as previously described (Arakaki et al, 2018). Briefly, epochs were filtered between 30 and 80 Hz.…”

Microstates-based resting frontal alpha asymmetry approach for understanding affect and approach/withdrawal behavior

“…This enables us in concluding that the positive correlation of affect and approach/ withdrawal measures with frontal asymmetry score α α − lpha lpha (ln( ) ln( )) Right L eft is the resultant of left hemispherical neuronal activity and vice versa. However, recently, many neuro-vascular studies [48][49][50][51] have observed alpha-BOLD synchronization wherein the alpha power correlates positively with neural activation during task engagement. Hence, there is a need to fully understand the neurovascular coupling and neural underpinning associated with frontal EEG asymmetry 5 and how alpha-BOLD synchronization or desynchronization during resting-state associates with affect and approach/withdrawal behavior.…”