Strong resemblance in the amplitude of oscillatory brain activity in monozygotic twins is not caused by “trivial” similarities in the composition of the skull

Abstract

Previous twin studies have shown strong heritability of electroencephalogram amplitude characteristics, such as power spectra. However, it has been suggested that these high heritabilities may reflect ''trivial'' twin resemblance in intervening tissues such as the skull. Here we demonstrate strong monozygotic twin correlation (0.79 < r < 0.88) of eyes-closed resting-state magnetoencephalogram power, which is insensitive to intervening tissues. These results confirm that brain activity itself is highly heritable.

Genetic influence demonstrated for MEG-recorded somatosensory evoked responses

“…Although we tested a large number of individuals for a MEG study ( N =68 in total), the sample size is still relatively limited for a MZ versus DZ twin‐pairs comparison of resemblance. Nevertheless, the present finding of a genetic influence on amplitudes of evoked brain activity measured with MEG is in agreement with our recent findings for power of ongoing brain activity during rest (van 't Ent et al, 2009) and with previous EEG studies on larger twin samples (van Beijsterveldt & Van Baal, 2002). The present results therefore substantiate that our previous conclusion that higher MZ resemblance for amplitudes of ongoing brain activity in EEG traces is not just reflecting greater MZ concordance in intervening biological tissues (van 't Ent et al, 2009) can also be extended to amplitudes of evoked brain responses.…”

“…Here we demonstrate significantly smaller amplitude differences within MZ compared to DZ twin pairs for the complete SEF time series (across left and right hand SEFs: 0.37 vs. 0.60 pT 2 and 0.28 vs. 0.39 pT 2 for primary [SI] and secondary [SII] sensory cortex activation) and higher MZ than DZ wave shape correlations (.71 vs. .44 and .52 vs. .35 for SI and SII activation). Our findings indicate a genetic influence on MEG‐recorded evoked brain activity and also confirm our recent conclusion (van 't Ent, van Soelen, Stam, De Geus, & Boomsma, 2009) that higher MZ resemblance for EEG amplitudes is not trivially reflecting greater MZ concordance in intervening biological tissues.…”

“…Further, for heritabilities of EEG amplitudes, it has been suggested that MZ twin resemblance may be strongly inflated because of greater MZ similarity of biological tissues between the brain and EEG electrodes, primarily the skull, which are also under genetic control (Kohn, 1991). In a recent study (van 't Ent, van Soelen, Stam, De Geus, & Boomsma, 2009), we disproved this hypothesis for ongoing resting state brain activity by showing that large MZ twin correlations for power in the classic frequency bands remain if brain activity is recorded with MEG, which is virtually undisturbed by intervening tissues (Okada, Lahteenmaki, & Xu, 1999;Wolters et al, 2006). The use of MEG, rather than EEG, in the present study also allowed us to investigate if this finding applies equally to evoked brain response amplitudes.…”

Why some people discount more than others: baseline activation in the dorsal PFC mediates the link between COMT genotype and impatient choice

“…In fact, resting EEG measures are among the most heritable traits in humans (De Geus, 2010), with heritability estimates of 70–96% (Smit et al, 2005; Zietsch et al, 2007; van ‘t Ent et al, 2009). Various studies have investigated the intraindividual stability of resting EEG, revealing test–retest reliabilities of up to 0.8 over a period of up to 5 years (Dunki et al, 2000; Smit et al, 2005; Napflin et al, 2007).…”

Resting-State Oscillatory Activity in Children Born Small for Gestational Age: An MEG Study

“…This frequency band was not examined in the neonates investigated by Ozdemir et al Furthermore, distinguishing true brain gamma band oscillations from gamma band activity caused by muscle artifacts using EEG is difficult as recently has been shown (Whitham et al, 2007). Unlike EEG, MEG has the advantage of being insensitive to skull-thickness and skin-conductance (Ent et al, 2009), and no reference electrode is required. Possible differences in skull-thickness between AGA and SGA born children, could therefore not have affected our estimated MEG power spectra.…”