Left hemispheric \u03b1 band cerebral oscillatory changes correlate with verbal memory

Toshihiko Araki,Masayuki Hirata,Yoshiyuki Watanabe

doi:10.1038/s41598-020-72087-3

Toshihiko Araki, Masayuki Hirata + Show 1 more

Open Access

https://doi.org/10.1038/s41598-020-72087-3

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Abstract

Event-related synchronisation (ERS) and event-related desynchronisation (ERD) have been observed via magnetoencephalography (MEG) in the language-dominant hemisphere. However, the relationship between ERS/ERD and clinical language indices is unclear. Therefore, the present study evaluated brain activity utilising MEG during a verb generation task in 36 subjects and determined ERS/ERD power values in θ, α, β, low γ and high γ frequency bands. To measure clinical language indices, we adopted Wechsler Memory Scale-revised. We observed ERD in the α band from the bilateral occipital to the left central brain region, in the β band from the bilateral occipital to the left frontal region and in the low γ band a high-power signal in the left frontal region. We also observed ERS in the θ band in bilateral frontal region and in the high γ band in bilateral occipital region. Furthermore, we found a significant negative correlation between α-band ERD power at the left postcentral gyrus and medial superior frontal gyrus and verbal memory score (correlation coefficients = − 0.574 and − 0.597, respectively). These results suggest that individuals with lower linguistic memory have less desynchronised α-band ERD power and α-band ERD power in the left hemisphere may be a neurophysiological biomarker for verbal memory.

Highlights

It has been reported that the spatiotemporal distribution of ERS/ERD varies in each frequency band in healthy subjects during a silent reading task[15]
We obtained ERS/ERD power measurements that correlate to brain activity during language tasks in 160 cortical regions
During the verb generation task, differences in spatial distribution were revealed in five frequency bands—θ, α, β, low γ and high γ

Summary

Introduction

It has been reported that the spatiotemporal distribution of ERS/ERD varies in each frequency band in healthy subjects during a silent reading task[15]. It has been reported that lateralising variations in ERD in the β band or the low γ band can function as a non-invasive index for estimating the language-dominant hemisphere during language tasks in patients with epilepsy and brain tumour[18,19,20]. Based on the results of these studies, we hypothesised that there is some correlation between cerebral oscillatory changes that occur during language tasks and actual language ability and measured cerebral oscillatory changes using MEG, which directly reflects neural electrical activity. The present study aimed to investigate the relationship between a clinical verbal memory index and languagerelated brain activity as detected by MEG. We used MEG to measure ERS/ERD at θ (3–8 Hz), α (8–13 Hz), β (13–25 Hz), low γ (25–50 Hz) and high γ (50–100 Hz) frequency bands during a verb generation task. We examined the correlation between spatiotemporal power in the brain and verbal memory score in Wechsler Memory Scale-revised (WMS-R), a general memory test

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