Higher EEG Power Research Articles

Comparative utility of MRI and EEG for early detection of cortical dysmaturation after postnatal systemic inflammation in the neonatal rat

BackgroundExposure to postnatal systemic inflammation is associated with increased risk of brain injury in preterm infants, leading to impaired maturation of the cerebral cortex and adverse neurodevelopmental outcomes. However, the optimal method for identifying cortical dysmaturation is unclear. Herein, we compared the utility of electroencephalography (EEG), diffusion tensor imaging (DTI), and neurite orientation dispersion and density imaging (NODDI) at different recovery times after systemic inflammation in newborn rats. MethodsSprague Dawley rat pups of both sexes received single-daily lipopolysaccharide (LPS; 0.3 mg/kg i.p.; n = 51) or saline (n = 55) injections on postnatal days (P)1, 2, and 3. A subset of these animals were implanted with EEG electrodes. Cortical EEG was recorded for 30 min from unanesthetized, unrestrained pups at P7, P14, and P21, and in separate groups, brain tissues were collected at these ages for ex-vivo MRI analysis (9.4 T) and Golgi–Cox staining (to assess neuronal morphology) in the motor cortex. ResultsPostnatal inflammation was associated with reduced cortical pyramidal neuron arborization from P7, P14, and P21. These changes were associated with dysmature EEG features (e.g., persistence of delta waveforms, higher EEG amplitude, reduced spectral edge frequency) at P7 and P14, and higher EEG power in the theta and alpha ranges at P21. By contrast, there were no changes in cortical DTI or NODDI in LPS rats at P7 or P14, while there was an increase in cortical fractional anisotropy (FA) and decrease in orientation dispersion index (ODI) at P21. ConclusionsEEG may be useful for identifying the early evolution of impaired cortical development after early life postnatal systemic inflammation, while DTI and NODDI seem to be more suited to assessing established cortical changes.

399 Source Localization of Burst Suppression in Post-Cardiac Arrest Patients

OBJECTIVES/GOALS: Burst suppression is a neurophysiological marker associated with severe hypoxic-ischemic injury following cardiac arrest. The goal of this study is to identify the anatomical regions of the brain associated with burst suppression post-cardiac arrest. METHODS/STUDY POPULATION: 86 comatose patients post-cardiac arrest admitted to the neurological-ICU from Massachusetts General Hospital and Brigham and Women’s Hospital were included in this study. EEG data after return of spontaneous circulation were preprocessed and artifact was rejected. Burst segments were extracted for source localization analysis from epochs with burst suppression. Four bursts for each patients were manually selected. The source of the bursts were obtained using the Champagne algorithm and mapped on the Desikan-Killiany atlas. The source for each burst was defined as any region of interest (ROI) with power > = 75th percentile relative to all ROIs. The power of the bursts at each source was correlated with the burden of brain injury measured using apparent diffusion coefficient (ADC) per ROI. RESULTS/ANTICIPATED RESULTS: 48 (56%) patients had burst suppression. 5 (10.4%) of patients with burst suppression were independent at the time of hospital discharge. Preliminary analyses was performed on 6 patients (24 bursts in total). ROI’s determined to be sources in a majority of the burst (>=13) were bilateral superior frontal, rostral middle frontal, parstriangularis precentral, superior parietal, inferior parietal, right post central, superior temporal, lateral occipital, and left middle temporal ROI. A lower mean ADC intensity was associated with a higher EEG power in the bilateral superior frontal (r = -0.80, p < 0.0001; r = -0.677, p < 0.001, respectively), left superior parietal (r = -0.53, p = 0.009), left middle temporal (r = -0.43, p = 0.042) ROI. DISCUSSION/SIGNIFICANCE: The source of bursts in patients post-cardiac arrest experiencing burst suppression is not well defined. This study will improve our understanding of how burst suppression is a measure of cortical injury, how it may relate to the burden of injury found on ADC imaging, and patient outcomes.

Electroencephalography Measures are Useful for Identifying Large Acute Ischemic Stroke in the Emergency Department

Background: Early diagnosis of stroke optimizes reperfusion therapies, but behavioral measures have incomplete accuracy. Electroencephalogram (EEG) has high sensitivity for immediately detecting brain ischemia. This pilot study aimed to evaluate feasibility and utility of EEG for identifying patients with a large acute ischemic stroke during Emergency Department (ED) evaluation, as these data might be useful in the prehospital setting. Methods: A 3-minute resting EEG was recorded using a dense-array (256-lead) system in patients with suspected acute stroke arriving at the ED of a US Comprehensive Stroke Center. Results: An EEG was recorded in 24 subjects, 14 with acute cerebral ischemia (including 5 with large acute ischemic stroke) and 10 without acute cerebral ischemia. Median time from stroke onset to EEG was 6.6 hours; and from ED arrival to EEG, 1.9 hours. Delta band power (P = .004) and the alpha/delta frequency band ratio (P = .0006) each significantly distinguished patients with large acute ischemic stroke (n = 5) from all other patients with suspected stroke (n = 19), with the best diagnostic utility coming from contralesional hemisphere signals. Larger infarct volume correlated with higher EEG power in the alpha/delta frequency band ratio within both the ipsilesional (r = −0.64, P = .013) and the contralesional (r = −0.78, P = .001) hemispheres. Conclusions: Within hours of stroke onset, EEG measures (1) identify patients with large acute ischemic stroke and (2) correlate with infarct volume. These results suggest that EEG measures of brain function may be useful to improve diagnosis of large acute ischemic stroke in the ED, findings that might be useful to pre-hospital applications.

Perinatal antibiotics alter preterm infant EEG and neurobehavior in the Family Nurture Intervention trial.

Early exposure to antibiotics has been shown to increase risk for poor neurobehavioral development, particularly with regard to attention deficit disorders. Clinically, electroencephalography (EEG) is increasingly used as a biomarker of these deficits. Less is known about the effects of antibiotics on neurobehavioral and neurophysiological outcomes in preterm infants, a population at particularly high risk for attention deficits and perinatal antibiotic exposure. This study examines the effects of perinatal antibiotic exposure on neonatal EEG and attention deficits as measured by the Child Behavior Checklist in 4- to 5-year-old children who were enrolled in an NICU-based randomized controlled trial comparing Family Nurture Intervention (FNI) to standard care. Antibiotic-exposed infants had increased attention problems and there was a main effect of antibiotic exposure such that exposed infants had higher EEG power. This effect was fourfold greater in infants who received standard NICU care compared to those who received the intervention, suggesting a buffering effect of the intervention. We hypothesize that the relationship between antibiotic exposure and altered neurodevelopment may be due to effects of antibiotics on the microbiome, and that FNI may buffer these adverse consequences.

Physical Activity, Nutrition, Cognition, Neurophysiology, and Short-Time Synaptic Plasticity in Healthy Older Adults: A Cross-Sectional Study.

The aging brain undergoes remodeling processes because of biological and environmental factors. To counteract brain aging, neuronal plasticity should be preserved. The aim of this study was to test if the capacity of generating short-time synaptic plasticity in older adults may be related to either physical activity, nutritional status, cognition, or neurophysiological activity. Thirty-six participants (mean age 73.3 ± 5.9 years) received transcranial magnetic stimulation in combination with peripheral nerve stimulation to experimentally induce short-time synaptic plasticity by paired associative stimulation (PAS). Adaptations in neuronal excitability were assessed by motor-evoked potential (MEP) in the right m. tibialis anterior before and after PAS. The Physical Activity Questionnaire 50+ and the StepWatchTM captured physical activity levels. Nutritional status was assessed by the Mini Nutritional Assessment. Cognition was assessed by reaction time for a divided attention test and with the Montreal Cognitive Assessment. Neurophysiological activity was assessed by electroencephalography during the divided attention test. MEPs of the highest stimulation intensity resulted significantly different comparing before, 5 min, or 30 min after PAS (p < 0.05). Data-driven automatic hierarchical classification of the individual recruitment curve slopes over the three-time points indicated four different response types, however, response groups did not significantly differ based on physical activity, nutritional status, cognition, or neurophysiological activity. In a second-level analysis, participants having an increased slope showed a significant higher energy expenditure (z = -2.165, p = 0.030, r = 0.36) and revealed a significant higher power activity in the alpha frequency band (z = -2.008, p = 0.046, r = 0.37) at the prefrontal-located EEG electrodes, compared to the participants having a decreased slope. This study hints toward older adults differing in their neuronal excitability which is strongly associated to their short-time synaptic plasticity levels. Furthermore, a physically active lifestyle and higher EEG power in the alpha frequency band seem to be connected to the capacity of generating long-term potentiation-like synaptic plasticity in older adults. Future studies should consider more sensitive assessments and bigger sample sizes to get a broad scope of the older adults’ population.

T123. Amplitudes of motor evoked potentials are modulated by preceding a band oscillations: A closed-loop EEG-TMS study

Introduction The amplitudes of MEPs in the resting state are considerably variable in each TMS. This variability of MEP amplitudes may reflect the fluctuation of the excitability of the primary motor cortex (M1). The neural substrates of determining MEP amplitudes for each TMS are still under the debate. There have been a few reports that deals with the relationship between MEP amplitudes and EEG oscillations in the offline analysis (e.g. Maki and Ilmoniemi, 2010). However, an attempt to explore the link between M1 and neural oscillations by a closed-loop EEG-MEP system is scarce. We have developed the closed-loop system and examined the relationship between EEG oscillations and MEP amplitudes. Methods Eighteen healthy adults (21–47 y.o, M:F = 15:3) participated in this study. EEGs were recorded at C3 with four surrounding electrodes, referred to the linked earlobe. Then, EEG signals at the C3 electrode were remontaged by source derivation and Fourier analyzed in the online to obtain EEG power of α or β band. The individual peak frequency of each band was determined in each subject before the MEP sessions using EEGs for about one minute in the resting state. When the online EEG power during MEP sessions reached the predefined threshold of high or low EEG power, a TMS pulse was delivered to record MEPs. About 50 MEPs were obtained for each of high/low power conditions. After recording MEPs, the MEP amplitudes of the high EEG power were compared with those of low power. The analyses were conducted for each of α and β band, respectively. Results MEPs were successfully recorded by the closed-loop system using EEG at C3. MEP amplitudes of the high EEG power condition were significantly higher than those of the low power condition in the α band. On the contrary, MEP amplitudes of the closed-loop by the β band were not significantly different between the conditions of high EEG power and that of low power. Conclusion We demonstrated that the high EEG power in α band resulted in higher MEP amplitudes compared with those of the low power by the customized closed-loop EEG-TMS system. Thus, the higher α power at C3 can be indicative of the higher M1 excitability. Event-related desynchronization is often reported that α or β power decreases before the hand movement (Stancak and Pfurtscheller, 1995). However, this experiment was conducted under the resting state. Therefore, the mechanism that modulates M1 excitability may be different from that of the premovement period. The α power around the central region is reported to originate from the primary sensory cortex (S1) while β power from M1 (Salmelin et al., 1995). It is also well known that M1 and S1 are tightly linked and modulate excitability between each other. Therefore, S1 oscillations may play a more important role to determine M1 excitability through M1-S1 connectivity.

Affective Modulation of Brain and Autonomic Responses in Patients With Fibromyalgia.

Emotional dysregulation and abnormal processing of affective information are thought to play a significant role for the maintenance of pain in fibromyalgia. The motivational priming hypothesis states that negative emotions could increase pain via activation of the aversive system, thus leading to an affective modulation of defensive reflexes. Nevertheless, little is known about peripheral and central correlates of affective reflex modulation in fibromyalgia. Thirty patients with fibromyalgia and 30 healthy individuals were asked to view three video clips from a self-perspective to induce specific mood states. Video clips consisted of the same virtual walk through different locations of a park under three affective environments (unpleasant, pleasant, and neutral). Startle eyeblink reflex and heart rate response elicited by abrupt startle noises, as well as heart rate variability and electroencephalography (EEG) oscillations were recorded when participants were passively viewing the virtual environments. Patients with fibromyalgia rated all environments as more negative and arousing than did healthy controls (p values < .05). Nevertheless, startle eyeblink reflex and heart rate response were lower in patients with fibromyalgia than in healthy controls when viewing all three environments (p values < .05). Patients with fibromyalgia also displayed lower heart rate variability, as well as higher EEG power (2-22 Hz) during all environments than did healthy controls (p values < .05). Patients with fibromyalgia were characterized by relevant deficits in affective modulation of startle and cardiac responses, heart rate variability, and EEG power spectra in response to sustained induction of affective states. These findings suggest an alteration of emotional and attentional aspects of information processing at subjective, autonomic, and central nervous system levels.

Task complexity modulates pilot electroencephalographic activity during real flights

Most research connecting task performance and neural activity to date has been conducted in laboratory conditions. Thus, field studies remain scarce, especially in extreme conditions such as during real flights. Here, we investigated the effects of flight procedures of varied complexity on the in-flight EEG activity of military helicopter pilots. Flight procedural complexity modulated the EEG power spectrum: highly demanding procedures (i.e., takeoff and landing) were associated with higher EEG power in the higher frequency bands, whereas less demanding procedures (i.e., flight exercises) were associated with lower EEG power over the same frequency bands. These results suggest that EEG recordings may help to evaluate an operator's cognitive performance in challenging real-life scenarios, and thus could aid in the prevention of catastrophic events.

The Effect of Foster Care on Social Skills

Almas AN, Degnan KA, Radulescu A, et al. Effects of early intervention and the moderating effect of brain activity on institutionalized children’s social skills at age 8. PNAS. 2012; 10(Suppl 2): 17228-17231; doi: 10.1073/pnas.1121256109Investigators from multiple institutions sought to understand the effect of early foster care placement on the social skills of previously institutionalized children when they reached middle childhood. This study was part of the Bucharest Early Intervention Project (BEIP) that began in 2001. BEIP is a randomized controlled trial of foster care as an intervention for children abandoned at birth and placed in 1 of 6 institutions for young children in Bucharest, Romania. At the outset of the BEIP, 136 institutionalized children were randomized to either foster care or usual care in the institution in which they currently resided. Children who were randomized to foster care were initially placed at ages 7 to 35 months. A control group of non-institutionalized children from the Bucharest community were also enrolled and were matched on age and gender to children in the intervention groups.For the current study, children had their attachment security to a primary caregiver (foster mother or favorite caregiver in the institution) assessed by the preschool version of the Strange Situation Procedure when they were 42 months old. When participants were 8 years old, brain electrical activity (EEG) was obtained; EEG power in the alpha band (7-12 Hz) was computed, since alpha activity is associated with attention and processing of sensory information and high alpha power reflects cortical maturity.1 The primary outcome was social skills which were measured by administering the Social Skills Rating System (SSRS) to their teachers when the children were 8 years old. Social skills of children in each of the 3 groups were compared, and the effects of age at foster care placement, EEG alpha power, and attachment security on this outcome were assessed.In the present study, there were 44 children in the usual care group, 52 in the foster care group, and 97 in the control group. Only 12 children in the usual care group were still living in an institution at age 8 years. Overall, children in the control group were rated significantly higher on social skills than children in the foster care and usual care groups. However, children placed in foster care before 20 months of age were rated no differently on social skills than control children and were rated significantly higher than usual care children. High EEG power in the alpha band among usual care and foster care children was significantly associated with better attachment security and social skills. There was no significant relationship between attachment security and social skills in usual care and foster care children who had low EEG power in the alpha band.The authors conclude that forming secure foster care relationships positively influences social skills of children who have experienced severe social deprivation from early institutionalization, and that alpha electrical activity appears important in the relationship between attachment and social skills.Middle childhood is a period of increasing interest to both foster and adoptive parents because poor social skills at this critical time in a child’s life can lead to rejection and exclusion by their peers during the transition to adolescence.2 Wiik et al recently reported that postinstitutionalized children have a greater risk of attention-deficit hyperactivity disorder symptoms and emotional or internalizing behavioral disorders than children in foster care/minimal institutionalization and control children (see AAP Grand Rounds, June 2011;25[6]:623). Erol et al found that institutionalized adolescents with few friends and poor relationships have more internalizing and externalizing problem behaviors, which can persist into and complicate their adulthood.4In the current study the BEIP provided researchers a unique opportunity to evaluate how variations in attachment relationships can influence the negative impact of early institutionalization. The investigators have proffered evidence that foster care has the expected positive influence on the social development of children who have experienced deprivation, as long as the intervention occurs early enough in life. However, the results also demonstrate that future research must consider other factors, such as brain development, which can dramatically affect the attachment-social skills relationship.Life is full of limited time offers. For institutionalized children, this study now helps pinpoint the deadline (ie, 20 months of age) after which a critical intervention may no longer change the future bleak outcome and direction of a child’s life. And, like the hidden catches in many of these limited time offers, there is no guarantee that a good intervention will result in the desired outcome.

Study on EEG power and coherence in patients with mild cognitive impairment during working memory task

To investigate the features of electroencephalography (EEG) power and coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Thirty-five patients (17 males, 18 females; 52-71 years old) and 34 sex- and age-matched controls (17 males, 17 females; 51-63 years old) were recruited in the present study. Mini-Mental State Examination (MMSE) of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls (P>0.05). Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels: right and left frontal (F3, F4), central (C3, C4), parietal (P3, P4), temporal (T5, T6) and occipital (O1, O2); inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta (1.0-3.5 Hz), theta (4.0-7.5 Hz), alpha-1 (8.0-10.0 Hz), alpha-2 (10.5 -13.0 Hz), beta-1 (13.5-18.0 Hz) and beta-2 (18.5-30.0 Hz) frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high (P<0.05) in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P<0.05). However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at rest and during working memory tasks. Moreover, failure of normal cortical connections may be exist in MCI patients.