The relationship between GABA levels and spectral oscillatory dynamics in the neonatal brain.
Poster No:
1313
Submission Type:
Abstract Submission
Authors:
alice thomson1, Juliette Champaud2, Jucha Willers Moore1, Ines Tomazinho1, Beya Bonse1, Kathleen Colford1, Parvaneh Adibpour1, Lorenzo Fabrizi2, Nicolaas Puts1, Tomoki Arichi1
Institutions:
1King's College London, London, UK, 2University College London, London, UK
First Author:
Co-Author(s):
Introduction:
In the adult brain, GABA levels positively correlate with the power of beta and gamma band oscillations in multiple brain regions including the visual cortex [1-4]. This is driven by GABAergic interneuron activity within cortical circuits which in turn shapes neural synchrony [1-4]. During early brain development this relationship may differ because of changes in GABA function [5]. Here, we probe the relationship between magnetic resonance spectroscopy (MRS) measures of brain GABA levels and resting state electroencephalography (EEG) power spectral densities in the occipital lobe of healthy term neonates. We hypothesise that the relationship between GABA levels and neuronal oscillations is not present in the developing brain.
Methods:
Data were acquired from 8 term neonates. Three datasets were excluded following post-acquisition data quality checks. Data is thus reported from 5 neonates with a median age of 39.7 (range: 37.28 - 43.29) weeks postmenstrual age and 3 (range: 1-27) post-natal days at scan, 2 females. All infants were healthy at the time of scanning and had normal brain appearances. Both and EEG and MRS recordings were performed during natural sleep. Studies were performed with NHS ethics committee approval and written parental consent.
A Philips Achieva 3T at St. Thomas' Hospital London (32-channel neonatal head coil [6) was used to acquire MRS data from a 27ml voxel placed over the occipital lobe (OCC), centered on the midline (Figure 1). MRS was performed using GABA editing MEGA-PRESS [7]; 320 transients, 2048 data points, TE/TR:68/2000ms, VAPOR water suppression. MRS data were processed in Osprey. T2-weighted anatomical images were segmented using the developing Human Connectome Project pipeline [8] for alpha tissue correction of GABA concentrations [9]. Concentrations are reported in institutional units (i.u) and reported as GABA+ (GABA plus macromolecule contribution).
Resting-state EEG data were acquired same day prior to the MRI for 10-15 mins using a 32- or 25-channel cap (EasyCap GMbH) and a BrainProducts EEG system. Pre-processing steps were performed in MATLAB (2021a) and EEGLAB [10]. Raw data were filtered with a notch (48-52 Hz) and second-order bidirectional Butterworth bandpass (0.1 and 70Hz). Data were then epoched into 60-150s sections and denoised using ICA (0-5 components rejected; Figure 1C). Power spectral densities estimated with the Welch's method for each channel/subject and averaged across O1, O2, Oz, POz channels spanning the occipital area (Figure 1D).
Spearman's rho correlation coefficients were first calculated between GABA+ and frequency power in 1Hz-intervals from 0-70Hz before averaging across frequency bands (1-4Hz for delta, 4 –8Hz for theta, 8-12Hz for alpha, 13-30Hz for beta and 30-40Hz for gamma).
A Philips Achieva 3T at St. Thomas' Hospital London (32-channel neonatal head coil [6) was used to acquire MRS data from a 27ml voxel placed over the occipital lobe (OCC), centered on the midline (Figure 1). MRS was performed using GABA editing MEGA-PRESS [7]; 320 transients, 2048 data points, TE/TR:68/2000ms, VAPOR water suppression. MRS data were processed in Osprey. T2-weighted anatomical images were segmented using the developing Human Connectome Project pipeline [8] for alpha tissue correction of GABA concentrations [9]. Concentrations are reported in institutional units (i.u) and reported as GABA+ (GABA plus macromolecule contribution).
Resting-state EEG data were acquired same day prior to the MRI for 10-15 mins using a 32- or 25-channel cap (EasyCap GMbH) and a BrainProducts EEG system. Pre-processing steps were performed in MATLAB (2021a) and EEGLAB [10]. Raw data were filtered with a notch (48-52 Hz) and second-order bidirectional Butterworth bandpass (0.1 and 70Hz). Data were then epoched into 60-150s sections and denoised using ICA (0-5 components rejected; Figure 1C). Power spectral densities estimated with the Welch's method for each channel/subject and averaged across O1, O2, Oz, POz channels spanning the occipital area (Figure 1D).
Spearman's rho correlation coefficients were first calculated between GABA+ and frequency power in 1Hz-intervals from 0-70Hz before averaging across frequency bands (1-4Hz for delta, 4 –8Hz for theta, 8-12Hz for alpha, 13-30Hz for beta and 30-40Hz for gamma).
Results:
Occipital GABA+ levels was positively correlated with beta (rho = 0.90, p < 0.05) and gamma power (rho = 0.90, p < 0.05; Figure 2). There was no significant relationship between GABA+ levels and other frequency bands; delta (1-4Hz): rho = 0.10, p = 0.87, theta (4-8Hz): rho = 0.60, p = 0.28, alpha (8 – 12Hz): rho = 0.6, p = 0.228.
Conclusions:
Our findings show a positive correlation between GABA+ levels and EEG beta and gamma frequency powers in the neonatal brain. This suggests that GABAergic activity may have a similar role in influencing neuronal oscillations in the early post-natal period, as has been observed in the adult brain [1-4]. This can provide new insight into the development of the relationship between neurochemistry and synchronous neuronal activity in the human brain, which can be further complemented by exploring relationships with emerging patterns of functional connectivity.
Lifespan Development:
Early life, Adolescence, Aging
Normal Brain Development: Fetus to Adolescence 1
Novel Imaging Acquisition Methods:
EEG
MR Spectroscopy 2
Physiology, Metabolism and Neurotransmission :
Pharmacology and Neurotransmission
Keywords:
Development
Electroencephaolography (EEG)
GABA
Magnetic Resonance Spectroscopy (MRS)
NORMAL HUMAN
PEDIATRIC
Other - Neurodevelopment; Oscillatory; Neonatal
1|2Indicates the priority used for review
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