Analysis of infant cortical synchrony is constrained by the number of recording electrodes and the recording montage

Abstract

Dense array EEG Connectivity Brain development h i g h l i g h t sAnalysis of brain connectivity from the neonatal EEG is strongly enhanced by adding the number of electrodes. Sensitivity and specificity of cortical synchrony estimates depend on the analysis montage; average and Laplacian montage have the best performance. The number of electrodes defines the optimal montage and it also sets the limits for the level of analytic details. a b s t r a c tObjective: To assess how the recording montage in the neonatal EEG influences the detection of cortical source signals and their phase interactions. Methods: Scalp EEG was simulated by forward modeling 20-200 simultaneously active sources covering the cortical surface of a realistic neonatal head model. We assessed systematically how the number of scalp electrodes (11-85), analysis montage, or the size of cortical sources affect the detection of cortical phase synchrony. Statistical metrics were developed for quantifying the resolution and reliability of the montages. Results: The findings converge to show that an increase in the number of recording electrodes leads to a systematic improvement in the detection of true cortical phase synchrony. While there is always a ceiling effect with respect to discernible cortical details, we show that the average and Laplacian montages exhibit superior specificity and sensitivity as compared to other conventional montages. Conclusions: Reliability in assessing true neonatal cortical synchrony is directly related to the choice of EEG recording and analysis configurations. Because of the high conductivity of the neonatal skull, the conventional neonatal EEG recordings are spatially far too sparse for pertinent studies, and this loss of information cannot be recovered by re-montaging during analysis. Significance: Future neonatal EEG studies will need prospective planning of recording configuration to allow analysis of spatial details required by each study question. Our findings also advice about the level of details in brain synchrony that can be studied with existing datasets or by using conventional EEG recordings.

Theta and Alpha Oscillations during the Retention Period of Working Memory by rTMS Stimulating the Parietal Lobe

“…EEG phase differences are often used to investigate “inter-sites phase synchronization”, which is an estimation of the connectivity between two EEG electrode sites (van Mierlo et al, 2014 ; Kang et al, 2015 ; Tokariev et al, 2016 ). Phase locking value (PLV; Lachaux et al, 1999 ) is a possible means to represent the synchronization phenomena in EEG signals (Lachaux et al, 1999 ).…”

Cortical route for facelike pattern processing in human newborns

“…This property is generally attributed to the significantly thinner skull bones of the newborn. These studies suggest that by using a high spatial sampling of the scalp EEG and a realistic newborn head model and conductivity values (more than 1 order of magnitude higher than the adult ones) (31, 32), we could compute a reliable source reconstruction of the newborn's EEG (33,34). With these indications, taking advantage of high-density EEG recordings, we estimated the cortical generators of the scalplevel effects with a source localization model based on newborn's realistic anatomical structure and electrical properties (34).…”

Cortical responses to tactile stimuli in preterm infants

“…In addition to the contralateral SER to hand stimulation, we also detected a systematic albeit smaller ipsilateral response (iSER), confirming the prior work of Hrbek et al (). Our extensive theoretical and empiric studies on newborn EEG signals (Gargiulo, Belfiore, Friethgeirsson, Vanhatalo, & Ramon, ; Odabaee, Freeman, Colditz, Ramon, & Vanhatalo, ; Odabaee et al, ; Tokariev, Vanhatalo, & Palva, ), including works on conventional evoked potentials (Nevalainen et al, ) in term infants, have shown that newborn scalp EEG signal is spatially very specific. Hence, the present results cannot be explained by spatial smearing of cortical signals akin to what is commonly seen in the adult scalp EEG studies.…”