Changes in autonomic function and EEG power during mental arithmetic task and their mutual relationship

Meditation is a specific consciousness state in which deep relaxation and increased internalized attention coexist. Autonomic nervous activity during meditation was reported to be characterized by decreased sympathetic activity and increased parasympathetic activity. And concerning EEG power, slow alpha power and fast theta power increased during meditation. On the other hand, mental arithmetic (MA) tasks have been reported to induce an increase in blood pressure and heart rate with enhanced sympathetic activity. However, changes in autonomic nervous activity and EEG power during MA tasks and their mutual relationship have not been adequately studied. In the present study, we quantitatively analyzed the changes in autonomic nervous activity using heart rate variability (HRV) and EEG power during MA task in 30 healthy volunteers. MA task induced significant increases in normalized LF, LF/HF ratio (as a sympathetic index), and a decrease in normalized HF (as a parasympathetic index). On the other hand, significant decrease in EEG power (slow theta: 4-6 Hz and fast alpha: 10-13 Hz in the posterior region and fast theta: 6-8 Hz and slow alpha: 8-10 Hz in all the regions) were induced by MA task. Further evaluation of these changes showed a negative correlation between the change rates (with the control resting condition as the baseline) in fast alpha power and that in LF/HF. These results suggest that specific correlated relationships exist between the change in autonomic nervous activity and EEG power depending on the difference in mental task (i.e., meditation or MA).     

Central and peripheral contributions to control of heart rate during heat acclimation

The contributions of the autonomic nervous system and the cardiac pacing cells in the development of heat-acclimation-induced bradycardia were analyzed, and the effect of heat acclimation on the chronotropic response of the heart to heat stress (40° C) was studied. Rats were acclimated at 34° C for 0, 5, 14, 30 and 60 days. Heart rate (HR) was measured in conscious animals, using chronic subcutaneous electrodes. Sympathetic and parasympathetic influences were studied by IP administration of 0.1 and 1 mg/100 g body weight atropine and propranolol respectively, while intrinsic HR (HR_i) was measured following administration of both drugs simultaneously. The effects of carbamylcholine and norepinephrine on the beating rate of isolated rat atria were investigated to study pacemaker responsiveness to neutrotransmitters. Up to day 14 of heat acclimation, bradycardia was attained by tonic parasympathetic acceleration (18%) and temporal sympathetic withdrawal (0.8% on day 14), to compensate for the gradually augmented HR_i (2.5% and 8% on days 5 and 14, respectively). Following long-term acclimation HR_i declined below pre-acclimation rate. This was associated with resumed sympathetic activity (16% and 10% on days 30 and 60 respectively) while parasympathetic activity continued to be high (18%). Tachycardia, known to occur with severe uncontrolled body hyperthermia, was attenuated following heat acclimation by 42%. It was concluded that during the initial phase of heat acclimation bradycardia is achieved primarily by changes in autonomic influences, while following long-term acclimation, changes in the intrinsic properties of the pacing cells (HR_i) and the autonomic system both play a role.     

Cardiovascular effects of morning nutrition in preadolescents

The cardiovascular response to eating has been extensively investigated in adults, but comparable data in children are lacking. In this investigation, heart-rate and heart-rate variability were evaluated in preadolescents during resting periods in the morning initially while participants maintained overnight fasting, and again after the participants either ate a standardized breakfast or continued fasting. Relative to the initial fasting period, heart rate (HR) increased slightly in fed participants and decreased significantly in those who continued to fast. These effects were associated with significant increases in low- (LF: 0.04-0.15 Hz; primarily sympathetic influences) and high-frequency (HF:0.15-0.5 Hz; parasympathetic influences) spectral components in fasting participants and with nonsignificant decreases in both components in fed participants. Although these HF changes are consistent with the observed heart-rate variations (i.e., increases and decreases in parasympathetic influence associated with decreased and increased HR, respectively), the LF increase with the slowing, and decrease with the acceleration of HR run counter to expected sympathetic effects on HR. The net effect of these modulations was unchanged sympathovagal balance (LF/HF) for fasting participants but a significant decrease for fed participants across recording periods. The results indicate that the continuation of overnight fasting is associated with a significant increase in parasympathetic activity that is attenuated by eating breakfast. Furthermore, the findings suggest that the parasympathetic contribution to the LF spectral component is significantly enhanced in preadolescents, and, consequently, the LF/HF ratio-generally considered to reflect sympathovagal balance-does not segregate sympathetic and parasympathetic influences in children.     

Respiratory variability in R-R interval during sinusoidal exercise

The R-R interval varies with the cycles of respiration. The response of the variability in the R-R interval with respiration was examined during sinusoidal cycle exercise in 12 healthy young male subjects. Work rate varied sinusoidally between 30 W and 60% maximal oxygen uptake for an 8-min period. The higher the heart rate (HR), the smaller was the magnitude of the variation in R-R interval with respiration (ΔRR). When HR increased with an increase in exercise intensity, however, ΔRR tended to decrease more markedly at lower HR. On the other hand, since ΔRR generally increased linearly during the decrease in HR with a reduction in exercise intensity, ΔRR was greater during decreases in HR than during increases in HR at a similar HR. These results suggest that the contribution of the withdrawal of cardiac parasympathetic activity to increases in HR with increases in exercise intensity during sinusoidal exercise were greater at lower HR, and that the cardiac parasympathetic system was more activated during HR decreases than during HR increases at the same HR. From our findings it would seem that such complex parasympathetic HR regulaltion during sinusoidal exercise, which depends on the level of HR and the direction of the change in HR, may be influenced by factors other than the parasympathetic system, such as the cardiac sympathetic system.     

Dynamics of swallowing-induced cardiac chronotropic responses in healthy subjects

Simultaneous recording of ECG and swallowing movements in healthy humans (n=23, age 20-57 years) showed that each swallow is accompanied by transient tachycardia with initial abrupt and pronounced heart rate increase. These rapid changes in heart rate (evaluation by maximum increment of heart rate over two successive heartbeats, HR_2bt) are typical of vagal chronotropic responses. The amplitude of tachycardia induced by a single swallow was significantly higher in the supine position (13.1±5.6 bpm) compared to the standing position (8.5±3.8 bpm; p<0.0001). Chronotropic responses to a series of three or more successive swallows consisted of two phases, the initial abrupt acceleration and subsequent slower growth of heart rate. In the standing position, the portion of the first rapid phase significantly decreased, while the portion of the slower phase increased compared to the supine position. The amplitude of tachycardia induced by a single swallow and parameter HR_2bt can serve as indices of the strength of parasympathetic modulation of the heart. By contrast, further slow increase in the heart rate determined by summation of responses to a series of successive swallows can result from not only inhibition of the parasympathetic influences, but also enhancement of sympathetic activity during swallowing.     

Heart rate variability as an index of autonomic imbalance in patients with recent myocardial infarction

Autonomic nervous activities are estimated in three groups of patients; Group A consists of patients who had experienced myocardial infarction (MI) within 2–6 weeks before the tests; Group B consists of patients who had MI more than one year previously; Group C consists of matched controls, free of cardiac disease. Autonomic activity is estimated using postural effects on heart rate variability (HRV): a sympathetic activity index is defined as HRV power within a low frequency band (0·04–0·12 Hz) in the tilt position and a parasympathetic activity index is defined as HRV power in a high frequency band (0·18–0·28 Hz) in the supine position. Results show that, relative to controls, Group A patients have reduced parasympathetic activity index (5+3 against 13+8, normalised units; p<0·05) and an increased ratio of sympathetic to parasympathetic activity (17+17 against 4+2; p<0·05). Group B is not significantly different from Group A or C. The period of 2–6 weeks post-MI thus appears to be characterised by depressed parasympathetic nervous activity which can be measured using HRV analysis.     

Coordination of the EEG and the heart rate of preterm neonates during quiet sleep

Aim of this study was to confirm that EEG bursts are associated with heart rate (HR) accelerations, and to investigate the synchronicity between quadratic phase couplings (QPC) courses of the EEG and HR before and during burst activity during quiet sleep in preterm newborns. The time-courses of QPC between frequency components of the EEG ([0.25–1.0 Hz] ↔ [4.0–6.0 Hz]) as well as between the Mayer–Traube–Hering (MTH) wave and the frequency component of the HR associated to the respiratory sinus arrhythmia (RSA) ([0.02–0.15 Hz] ↔ [0.4–1.5 Hz]) were investigated in five preterm neonates. During quiet sleep, the EEG alternates between burst and interburst activity. The burst onsets were used to trigger an averaging procedure for the EEG, HR, and QPC courses. It can be demonstrated that the envelopes of the EEG rise after the burst onset accompanied by an acceleration of HR before or at the burst maximum. The QPC courses show that the HR's QPC increases before or at the burst onset whereas the increase of the EEG's QPC is delayed. The synchronous changes of EEG and HR as well as of the corresponding QPC courses indicate a coupling between cortical, thalamocortical and neurovegetative brain structures. Such a coupling might be mediated by the MTH waves in the blood pressure.     

The relationships between autonomic function and heart rate in essential hypertension

The circadian variation of blood pressure (BP) may be mediated at least in part by circadian variation of autonomic nervous system activity. In the present study power spectral analysis of hourly R-R intervals for 24 hours was done to obtain the low frequency variability (LF: 0.04 to 0.15Hz) and high frequency variability(HF: 0.15 to 0.40Hz) in 93 patients with untreated essential hypertension. LF/HF ratio and HF were considered to be an index of sympathetic nervous activity and parasympathetic nervous activity, respectively. The relationship between heart rate (HR) and systolic blood pressure (SBP), diastolic blood pressure (DBP), HF, and LF/HF was examined. Both SBP and DBP were correlated positively with HR(r = 0.28, p < 0.05 and r = 0.27, p < 0.05, respectively) in the daytime. HF was correlated negatively and significantly with HR in both daytime and nighttime (r = -0.40, p < 0.05, and r = -0.38, p < 0.05 respectively). After averaging for SBP of 24 hours, HR in the patients whose SBP was 135mmHg or more was significantly higher than that in the patients whose SBP was less than 135mmHg. These results suggest that the decreased parasympathetic nervous activity seems to be responsible for the rise in BP.     

Gastric emptying,plasma ghrelin and autonomic nerve activity in diabetic rats

We have previously shown that the elevated plasma ghrelin accelerate emptying in the early stage of diabetes in rats. However, it remains unknown whether plasma ghrelin levels are still elevated in the late stage of diabetes. We studied whether solid gastric emptying and plasma ghrelin levels are altered 2–8 weeks after streptozotocin (STZ) injection. The development of autonomic neuropathy was evaluated by spectral analysis of heart rate variability (HRV). Gastric emptying was not different between control and diabetic rats at 4 weeks and 6 weeks, while it delayed at 8 weeks in STZ rats. The pre-prandial ghrelin levels were not significantly different between control and diabetic rats at 4–8 weeks. In control rats, the plasma ghrelin levels were significantly reduced 30 min after the feeding at 4–8 weeks. In contrast, there was no significant reduction of ghrelin levels observed in diabetic rats at 4–8 weeks. Plasma insulin levels were significantly increased 30 min after feeding in control rats, but not STZ rats, at 4–8 weeks. Both HF (parasympathetic activity) and LF (sympathetic activity) component were gradually reduced 6–8 weeks after STZ injection. It is suggested that hypoinsulinemia associated with diabetes increases plasma ghrelin levels. At the late stage of diabetes, gastric emptying is delayed despite increased plasma ghrelin levels. The delayed gastric emptying is mainly due to impaired activity of autonomic nerves at the late stage of diabetes.     

Parasympathetic nervous system control of heart rate responses to stress in offspring of hypertensives

The elevated heart rate response to stress in normotensive offspring of hypertensives (PH+) has been suggested to be a function of sympathetic nervous system activity. This study examined whether parasympathetic nervous system activity may also underlie familial differences in the heart rate response. Twenty-four subjects, half of whom were PH+, were exposed to four stressor tasks administered in counterbalanced order. Stressors were chosen based on previous research that suggested vagal contributions to the heart rate response. Stressors were a cold pack to the forehead, isometric hand grip, a noxious film, and a shock-avoidance video game task. Physiological measures included heart rate (HR), respiration rate (RR), and respiratory sinus arrhythmia (RSA). RSA values were corrected for corresponding RR by analysis of covariance. Familial differences in HR were observed in response to the hand grip and video game tasks. However, in both cases analyses suggest that familial differences in reactivity were a function of primarily sympathetic as opposed to parasympathetic influences. Familial differences in RSA were not observed for rest or tasks. This study found no evidence for parasympathetic mediation of familial differences in the heart rate response to the stressors employed.     

Cardiac autonomic nerve abnormalities in chronic heart failure are associated with presynaptic vagal nerve degeneration

Background: Understanding of the functional and structural disturbances of cardiac autonomic nerves in ventricular hypertrophy and eventual chronic heart failure (CHF) remains unclear. Methods and results: ECG signals were obtained by a radio transmitter from male Wistar rats that received monocrotaline (MCT) via subcutaneous injection. Heart rate (HR) and HR variability (HRV) were analyzed. The RR interval, total power (TP), low frequency (LF) power, high frequency (HF) power, and LF/HF (L/H) power ratio were measured. Ultrastructural changes in cardiac autonomic nerves at the sinoatrial (SA) node region were studied using an electron microscope. TP and HF powers in MCT-induced right ventricular hypertrophy (RVH) and eventual CHF were significantly decreased, and HR was significantly increased at week 5 or later after the MCT injection. The electron microscopic findings indicated the depletion of neurotransmitter vesicles and degradation of parasympathetic but not sympathetic nerve endings in the SA node region of the heart. Conclusion: MCT-induced RVH and CHF rats showed presynaptic vagal nerve degradation prior to sympathetic nerve derangement in the heart.     

Histamine in the posterodorsal medial amygdala modulates cardiovascular reflex responses in awake rats

Centrally injected histamine (HA) affects heart rate (HR), arterial blood pressure (BP), and sympathetic activity in rats. The posterodorsal medial amygdala (MePD) has high levels of histidine decarboxylase, connections with brain areas involved with the modulation of cardiovascular responses, and is relevant for the pathogenesis of hypertension. However, there is no report demonstrating the role of the MePD histaminergic activity on the cardiovascular function in awake rats. The aims of the present work were: 1) to study the effects of two doses (10-100 nM) of HA microinjected in the MePD on basal cardiovascular recordings and on baroreflex- and chemoreflex-mediated responses; 2) to reveal whether cardiovascular reflex responses could be affected by MePD microinjections of (R)-alpha-methylhistamine (AH3), an agonist of the inhibitory autoreceptor H3; and, 3) to carry out a power spectral analysis to evaluate the contribution of the sympathetic and parasympathetic components in the variability of the HR and BP recordings. When compared with the control group (microinjected with saline, 0.3 microl), HA (10 nM) promoted an increase in the MAP50, i.e. the mean value of BP at half of the HR range evoked by the baroreflex response. Histamine (100 nM) did not affect the baroreflex activity, but significantly decreased the parasympathetic component of the HR variability, increased the sympathetic/parasympathetic balance at basal conditions (these two latter evaluated by the power spectral analysis), and promoted an impairment in the chemoreflex bradycardic response. Microinjection of AH3 (10 microM) led to mixed results, which resembled the effects of both doses of HA employed here. Present data suggest that cardiovascular changes induced by baroreceptors and chemoreceptors involve the histaminergic activity in the MePD. This neural regulation of reflex cardiovascular responses can have important implications for homeostatic and allostatic conditions and possibly for the behavioral displays modulated by the rat MePD.     

Effect of body position on bilateral EEG alterations and their relationship with autonomic nervous modulation in normal subjects

This study investigated the effect of body position on the electroencephalogram (EEG) and autonomic nervous modulation, and the relationship between them using spectral analysis of EEG and heart rate variability (HRV). All healthy volunteers recruited had their electrocardiogram and EEG recorded for power spectral analysis. We found that when changing position from supine to upright, the EEG spectral components below the α band, such as δ and θ bands, were significantly decreased while the EEG spectral components above the α band, such as β, γ and ω bands, were significantly increased in both scalps. Correlation analysis showed that the θ rhythm of both scalps might be associated with the control of HR, the α and β rhythms of right scalp might be associated with vagal modulation, and the γ rhythm of left scalp might be associated with sympathetic modulation of the subject. Thus, some EEG components might be associated with the autonomic nervous modulation of the subject during positional change. There might be a mechanism located in the brain-stem which jointly controls both autonomic influences on heart rate and EEG activation.     

驾驶精神疲劳的心率变异性和血压变异性综合效应分析

驾驶精神疲劳是威胁人们健康与生命安全的严重问题.本研究的目的是基于心率变异性与血压变异性功率谱分析综合评估驾驶员精神疲劳.20个健康男性样本(28.8±4.3)岁参加90 min的模拟驾驶操作实验,实验后计算分析实验样本心率变异性和血压变异性的频域指标,如:低频成分(0.04～0.15 Hz,LF),高频成分(0.15～0.4Hz,HF),代频与高频比值(LF/HF);同时分析反映血流动力学指标的血压和心率.研究表明,样本在实验结束后交感神经兴奋性增强,迷走神经兴奋性减弱,交感迷走平衡性升高;同时,心率变异性与血压变异性的对应指标在实验过程中具有良好的相关性(P＜0.05).研究认为采用多变量综合效应分析方式评价自主神经系统功能是科学和客观的.     

Role of Sympathetic and Parasympathetic Nervous Systems in Heart Rate Regulation in Cats

The effects of atropine and β-adrenoceptor blockers on mean HR, wave structure of the cardiac rhythm, and chronotropic reaction to noise stress were examined in cats. Atropine (0.5 mg/kg) increased the mean HR and significantly decreased the spectrum power of HF, LF, and VLF oscillations. The decrease in HF power was most pronounced, which enhanced LF/HF ratio. Propranolol (0.5 mg/kg) decreased the mean HR and slightly increased the power of HF, LF, and VLF oscillations. Atenolol (2 mg/kg) exerted similar but more pronounced effects. β-Adrenoceptor blockers increased HF power to a greater extent than LF and VLF power, which led to a decrease in LF/HF ratio. Atropine markedly decreased the chronotropic reaction to stress. β-Adrenoceptor blockers produced no effect on the amplitude of this reaction, but accelerated restoration of initial HR. It is established that the changes in power spectrum of HR and the phase reflex reactions in cats are mediated by parasympathetic influences; the sympathetic system is involved only in the control of mean HR, probably in response to the level of animal activity. The changes in LF/HF ratio during blockade of sympathetic and parasympathetic systems are caused by opposite influences of these systems on HF oscillations, but not by hypothetic “sympathetic” and “parasympathetic” nature of LF and HF oscillations of the heart rhythm. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 140, No. 11, pp. 484–489, November, 2005     

Autonomic nervous control of heart rate during blood-flow restricted exercise in man

Summary Power spectra of instantaneous heart rate (f _c) allows the estimation of the contribution of sympathetic and parasympathetic control of f _c during steady-state conditions. The present study was designed to examine autonomic control of f _c as influenced by normal dynamic leg exercise and by ischemic leg exercise. Eight subjects performed supine cycle ergometry at 30% of their control peak work rate, with and without blood-flow restriction. Blood-flow restriction was induced by exposing the exercising legs to a supra-atmospheric pressure of 6.7 kPa (leg positive pressure; LPP). The exercise responses of arterial pressure and f _c increased (P<0.05) by LPP exposure. The exaggerated pressor response may be attributed to a chemoreflex drive originating in the ischemic muscles. Exposure to LPP during exercise also produced a significant decrease in parasympathetically mediated high frequency (HF; 0.15-1.00 Hz) fluctuation of f _c, as indicated by a decrease (P<0.05) in percent HF power compared to the control exercise level. During LPP exercise, the sympathetically mediated very low frequency (VLF; 0–0.05 Hz) fluctuation of f _c increased, as indicated by an increase (P<0.05) in percent VLF power above control exercise levels. Both LPP and control exercise conditions decreased (P<0.05) power in all frequency ranges of interest compared to their respective resting conditions. The results suggest that the increase in f _c associated with normal dynamic exercise was mediated predominantly by parasympathetic withdrawal, whereas the exaggerated f _c response during ischemic exercise resulted from a combination of cardiac sympathetic drive and parasympathetic withdrawal. The increase in sympathetic activity is attributable to a muscle chemoreflex drive, which also may have attenuated parasympathetic activity by reciprocal inhibition. Alternatively, augmented central command mediated parasympathetic withdrawal during ischemic exercise.     

The Association of Heart Rate Variability with Parkinsonian Motor Symptom Duration

Purpose

Impaired cardiovascular autonomic regulation is a non-motor symptom of Parkinson''s disease (PD) and may increase long-term morbidity. This study applied frequency-domain analysis of heart rate variability (HRV) to understand the progression of sympathetic and parasympathetic cardiac regulation in patients with PD.

Materials and Methods

In this cross-sectional study, 21 male and 11 female Taiwanese patients with advanced PD and 32 healthy gender- and age-matched subjects were enrolled. To minimize artifacts due to subject motion, daytime electrocardiograms for 5 minutes were recorded in awake patients during levodopa-on periods and controls. Using fast Fourier transformation, heart rate variables were quantified into a high-frequency power component [0.15-0.45 Hz, considered to reflect vagal (parasympathetic) regulation], low-frequency power component (0.04-0.15 Hz, reflecting mixed sympathetic and parasympathetic regulation), and low-frequency power in normalized units (reflecting sympathetic regulation). The significance of between-group differences was analyzed using the paired t-test. Pearson correlation analysis and stepwise regression analysis were applied to assess the correlation of patient age, PD duration, and disease severity (represented by the Unified Parkinson''s Disease Rating Scale) with each heart rate variables.

Results

Impaired HRV is significantly correlated with the duration of PD, but not with disease severity and patient age. Meanwhile, parasympathetic heart rate variable is more likely than sympathetic heart rate variable to be affected by PD.

Conclusion

PD is more likely to affect cardiac parasympathetic regulation than sympathetic regulation by time and the heart rate variables have the association with Parkinsonian motor symptom duration.     

The covariation of cortical electrical activity and cardiovascular responding.

Integrating findings from research concerning the cerebral and cardiovascular effects of increasing emotional intensity suggests that changes in functional cerebral system activation and changes in heart rate and blood pressure are related. Research has indicated that the left and right cerebral hemispheres are specialized for parasympathetic and sympathetic control of cardiovascular functioning. The present investigation sought to determine whether significant correlations existed between changes in the magnitude (microV) of alpha (8-13 Hz), low beta (13-21 Hz), and high beta (21-32 Hz) EEG activity at the frontal and temporal lobes and changes in heart rate as well as systolic and diastolic blood pressure. The results indicated that changes in the magnitude of each bandwidth analyzed were significantly correlated with changes in all three cardiovascular measures at several sites across the cerebral hemispheres, including the frontal and temporal lobes. The findings are discussed in terms of explaining the cardiovascular effects of increasing emotional intensity. Clinical implications of the findings are also discussed and suggestions for future research are provided.     

Investigating the relationship between fetus EEG,respiratory, and blood pressure signals during maturation using wavelet transform

In this study, we introduce the fast wavelet transform as a method for characterizing maturational changes in electrocortical activity, respiratory activity, and blood pressure in fetal lambs in early (110–122 days), mid (123–135 days), and late (136–144 days) third trimester (term 145 days). Each recording was 2 hr in duration. Wavelet decomposition was performed for six sets of parametersD _2j where 1≤j≤6. The six series wavelet transforms represent the following signal frequency bands: 1. 16–32 Hz; 2. 8–16 Hz; 3. 4–8 Hz; 4. 2–4 Hz; 5. 1–2 Hz; 6. 0.5–1 Hz. In the early group, power in the electrocephalogram (EEG) was highest in the fourth wavelet band, with relatively low power in the other bands. Increase in gestational age was characterized by increased power in all four wavelet bands. Power in the first wavelet band was significantly increased during low-voltage fast activity (LVFA) in the late group. The respiratory and blood pressure signals showed common frequency components with respect to time and were coincident with the LVFA EEG signal. Respiratory activity was only observed during some of the LVFA periods and was completely absent during high-voltage slow activity (HVSA) EEG. The respiratory signal showed dominant power in the fourth wavelet band, and less power in the third and fifth band. The blood pressure signal was also characterized by dominant power in the fourth wavelet band. This power was significantly increased during periods of respiratory activity. These results suggest a strong relationship between fetal EEG, blood pressure, and breathing movements.     

Reduced alpha and exaggerated theta power during the resting-state EEG in fragile X syndrome

This study characterizes the resting-state EEG in males with fragile X syndrome to reveal abnormalities in oscillatory brain dynamics. Analyses of the eyes-closed EEG epochs showed that the resting-state EEG in FXS can be characterized by elevated relative theta power (4–8 Hz) and reduced relative upper-alpha power (10–12 Hz). Although preliminary, these findings suggest that the well-documented imbalance in excitatory/inhibitory cortical circuit activity in FXS can be revealed the level of oscillatory behavior at the scalp. A next step for future studies is linking the EEG resting-state indices to cognitive and behavioral measures.