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Automated morphometric approaches are used to detect epileptogenic structural abnormalities in 3D MR images in adults, using the variance of a control population to obtain z-score maps in an individual patient. Due to the substantial changes the developing human brain undergoes, performing such analyses in children is challenging. This study investigated six features derived from high-resolution T1 datasets in four groups: normal children (1.5T or 3T data), normal clinical scans (3T data), and patients with structural brain lesions (3T data), with each n = 10. Normative control data were obtained from the NIH study on normal brain development ( n = 401). We show that control group size substantially influences the captured variance, directly impacting the patient's z-scores. Interestingly, matching on gender does not seem to be beneficial, which was unexpected. Using data obtained at higher field scanners produces slightly different base rates of suprathreshold voxels, as does using clinically derived normal studies, suggesting a subtle but systematic effect of both factors. Two approaches for controlling suprathreshold voxels in a multidimensional approach (combining features and requiring a minimum cluster size) were shown to be substantial and effective in reducing this number. Finally, specific strengths and limitations of such an approach could be demonstrated in individual cases. Hum Brain Mapp 35:3199-3215, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We compared the magnetic cerebral activity of 10 fetal subjects at two different gestational ages. Spontaneous cerebral activity was recorded with a large array magnetometer specially designed to conform to the maternal gravid abdomen during the third trimester of pregnancy. We recorded each fetal subject at least twice: first at less than 36 weeks and again after 36 weeks gestational age. Pervasive signal artifacts of maternal magnetocardiogram (MCG), respiration, uterine wall contractions, and fetal magnetocardiogram were removed with special filtering that preserved fetal cerebral signals. We used ultrasound to locate the fetal head immediately before and after the magnetic recordings. Auditory and visual evoked responses were also recorded for each fetal subject. The calculated origin for the spontaneous cerebral signals was verified to be at the ultrasound location for the fetal head and to be similar to the calculated locations for the cerebral evoked responses. The recordings for each fetal subject at less than and greater than 36 weeks gestational age were compared to the expected EEG findings for premature infants at comparable post conceptual ages. [Copyright &y& Elsevier]

Explores the issues related to political communication and debates in the United States. How the citizens patronized the televised debates between the 1976 presidential and vice-presidential candidates of the country; Summary of the learning by candidate and their favorability as viewed by the televiewer respondents; Information on the content of learning reflected by the candidates during debates.

Background: Magnetoencephalography (MEG) plays a preponderant role in the preoperative assessment of patients with drug‐resistant epilepsy (DRE). However, the magnetoencephalography of patients with drug‐resistant epilepsy can be difficult without sedation and/or general anesthesia. Our objective is to describe our experience with intravenous dexmedetomidine as sedation for magnetoencephalography and its effect, if any, on the ability to recognize epileptic spikes. Methods: In this retrospective study, we reviewed the records of 89 children who presented for Magnetoencephalography/electroencephalography (EEG) scans between August of 2008 and May of 2015. Data analyzed included demographics and the frequency of epileptic spikes. Sedated magnetoencephalography recordings were compared to nonsedated video‐electroencephalography (vEEG) recordings in the same patients to determine the impact of dexmedetomidine. Results: Spike frequency between magnetoencephalography with sedation and video‐electroencephalography without sedation was compared in 85 patients. Magnetoencephalography and video‐electroencephalography were considered clinically concordant in 80 patients (94.1%) and discordant in 5 patients (5.9%), all with less spikes during Magnetoencephalography. The median (range) bolus dose of dexmedetomidine was 2 (1‐2) mcg/kg. The median (range) infusion rate of dexmedetomidine was 2 (0.5‐4) mcg/kg/h. All patients experienced reductions in heart rate after administration of dexmedetomidine; these reductions were statistically, but not clinically, significant. Conclusions: Our results suggest that dexmedetomidine‐based protocol provides reliable sedation in children undergoing MEG scanning because of the high success rate, limited interictal artifacts, and minimal impacts on spike frequency. [ABSTRACT FROM AUTHOR]

Highlights • Resection of HGM language sites is associated with worse neuropsychological outcomes. • Working memory was significantly worse in patients with resection of HGM naming sites. • Neuropsychological evaluation of children with epilepsy should include multiple cognitive and language domains. Abstract Background Language mapping with high-gamma modulation (HGM) has compared well with electrical cortical stimulation mapping (ESM). However, there is limited prospective data about its functional validity. We compared changes in neuropsychological evaluation (NPE) performed before and 1-year after epilepsy surgery, between patients with/without resection of cortical sites showing HGM during a visual naming task. Methods Pediatric drug-resistant epilepsy (DRE) patients underwent pre-surgical language localization with ESM and HGM using a visual naming task. Surgical decisions were based solely on ESM results. NPE difference scores were compared between patients with/without resection of HGM naming sites using principal component (PC) analysis. Follow-up NPE scores were modeled with resection group as main effect and respective pre-surgical score as a covariate, using analysis of covariance. Results Seventeen native English speakers (12 females), aged 6.5–20.2 years, were included. One year after epilepsy surgery, first PC score increased by (mean ± standard deviation) 14.4 ± 16.5 points in patients without resection, whereas it decreased by 7.6 ± 24.6 points in those with resection of HGM naming sites (p = 0.040). This PC score represented verbal comprehension, working memory, perceptual reasoning (Wechsler subscales); Woodcock-Johnson Tests of Achievement; and Peabody Picture Vocabulary Test. Subsequent analysis showed significant difference in working memory score between patients with/without resection of HGM naming sites (−15.2 points, 95% confidence limits −29.7 to −0.7, p = 0.041). Conclusion We highlight the functional consequences of resecting HGM language sites, and suggest that NPE of DRE patients should include comprehensive assessment of multiple linguistic and cognitive domains besides naming ability. [ABSTRACT FROM AUTHOR]

Summary: Objective: We studied age‐related dynamics of information sharing among cortical language regions with electrocorticographic high‐gamma modulation during picture‐naming and story‐listening tasks. Methods: Seventeen epilepsy patients aged 4‐19 years, undergoing extraoperative monitoring with left‐hemispheric subdural electrodes, were included. Mutual information (MI), a nondirectional measure of shared information, between 16 pairs of cortical regions of interest, was computed from trial‐averaged 70–150 Hz power modulations during language tasks. Impact of age on pairwise MI between language regions and their determinants were ascertained with regression analysis. Results: During picture naming, significant increase in MI with age was seen between pairwise combinations of Broca's area, inferior precentral gyrus (iPreC), and frontal association cortex (FAC); Wernicke's area and posterior association cortex (PAC); and Broca's and Wernicke's areas. During story listening, significant age‐related increase in MI was seen between Wernicke's area and either Broca's area, FAC, or PAC; and between Broca's area and FAC. Significant impact of baseline intelligence quotient was seen on the relationship between age and MI for all pairs, except between Broca's area and iPreC. The mean MI was higher during naming compared to listening for pairs including iPreC with Broca's area, FAC, or PAC and was lower for pairs of Wernicke's area or PAC with anterior language regions. Significance: Information sharing matures with age "within" frontal and temporoparietal language cortices, and "between" Broca's and Wernicke's areas. This study provides evidence for distinct patterns of developmental plasticity within perisylvian language cortex and has implications for planning epilepsy surgery. [ABSTRACT FROM AUTHOR]

Summary: Objective: This prospective study compared the topography of high‐gamma modulation (HGM) during a story‐listening task requiring negligible patient cooperation, with the conventional electrical stimulation mapping (ESM) using a picture‐naming task, for presurgical language localization in pediatric drug‐resistant epilepsy. Methods: Patients undergoing extraoperative monitoring with subdural electrodes were included. Electrocorticographic signals were recorded during quiet baseline and a story‐listening task. The likelihood of 70‐ to 150‐Hz power modulation during the listening task relative to the baseline was estimated for each electrode and plotted on a cortical surface model. Sensitivity, specificity, accuracy, and diagnostic odds ratio (DOR) were estimated compared to ESM, using a meta‐analytic framework. Results: Nineteen patients (10 with left hemisphere electrodes) aged 4‐19 years were analyzed. HGM during story listening was observed in bilateral posterior superior temporal, angular, supramarginal, and inferior frontal gyri, along with anatomically defined language association areas. Compared to either cognitive or both cognitive and orofacial sensorimotor interference with naming during ESM, left hemisphere HGM showed high specificity (0.82‐0.84), good accuracy (0.66‐0.70), and DOR of 2.23 and 3.24, respectively. HGM was a better classifier of ESM language sites in the left temporoparietal cortex compared to the frontal lobe. Incorporating visual naming with the story‐listening task substantially improved the accuracy (0.80) and DOR (13.61) of HGM mapping, while the high specificity (0.85) was retained. In the right hemisphere, no ESM sites for aphasia were seen, and the results of HGM and ESM comparisons were not significant. Significance: HGM associated with story listening is a specific determinant of left hemisphere ESM language sites. It can be used for presurgical language mapping in children who cannot cooperate with conventional language tasks requiring active engagement. Incorporation of additional language tasks, if feasible, can further improve the diagnostic accuracy of language localization with HGM. [ABSTRACT FROM AUTHOR]

Objective This prospective study compared presurgical language localization with visual naming-associated high-γ modulation ( HGM) and conventional electrical cortical stimulation ( ECS) in children with intracranial electrodes. Methods Patients with drug-resistant epilepsy who were undergoing intracranial monitoring were included if able to name pictures. Electrocorticography ( ECoG) signals were recorded during picture naming (overt and covert) and quiet baseline. For each electrode the likelihood of high-γ (70-116 Hz) power modulation during naming task relative to the baseline was estimated. Electrodes with significant HGM were plotted on a three-dimensional (3D) cortical surface model. Sensitivity, specificity, and accuracy were calculated compared to clinical ECS. Results Seventeen patients with mean age of 11.3 years (range 4-19) were included. In patients with left hemisphere electrodes (n = 10), HGM during overt naming showed high specificity (0.81, 95% confidence interval [ CI] 0.78-0.85), and accuracy (0.71, 95% CI 0.66-0.75, p < 0.001), but modest sensitivity (0.47) when ECS interference with naming (aphasia or paraphasic errors) and/or oral motor function was regarded as the gold standard. Similar results were reproduced by comparing covert naming-associated HGM with ECS naming sites. With right hemisphere electrodes (n = 7), no ECS-naming deficits were seen without interference with oral-motor function. HGM mapping showed a high specificity (0.81, 95% CI 0.78-0.84), and accuracy (0.76, 95% CI 0.71-0.81, p = 0.006), but modest sensitivity (0.44) compared to ECS interference with oral-motor function. Naming-associated ECoG HGM was consistently observed over Broca's area (left posterior inferior-frontal gyrus), bilateral oral/facial motor cortex, and sometimes over the temporal pole. Significance This study supports the use of ECoG HGM mapping in children in whom adverse events preclude ECS, or as a screening method to prioritize electrodes for ECS testing. [ABSTRACT FROM AUTHOR]

Resective epilepsy surgery can improve seizures when the epileptogenic zone (EZ) is limited to a well-defined region. High frequency oscillations (HFO) have been recognized as having a high association with the seizure onset zone. Therefore, we retrospectively identified ictal HFOs and determined their relationship to specific intracranial features of cortical tubers in children with TSC who underwent resective surgery. We identified 14 patients with drug resistant epilepsy secondary to TSC who underwent subdural grid and strip implantation for presurgical evaluation and subsequent resection with adequate post-surgical follow-up. We aimed to determine the relationship between ictal HFOs, post-resection outcome and neuroimaging features in this population. The largest tuber was identified in all 14 patients (100%). Four patients (29%) had unusual tubers. HFOs were observed at ictal onset in all 14 patients. Seven of 10 patients with complete resection of HFOs were seizure free. The better seizure outcome (ILAE = 1–3) was achieved with complete HFO resection regardless of the unique TSC structural features (p = 0.0140). Our study demonstrates the presence of ripple and fast ripple range HFOs at ictal onset in children with TSC. Our study showed that complete HFO resection led to the better surgical outcome, independent of MR imaging findings. [ABSTRACT FROM AUTHOR]

Purpose There is wide variation in clinical practice regarding the role of electrocorticography immediately after resection (post-resection ECoG) for pediatric epilepsy surgery. Results can guide further resection of potentially epileptogenic tissue. We hypothesized that post-resection ECoG spiking represents a biomarker of the epileptogenic zone and predicts seizure outcome in children undergoing epilepsy surgery. Methods We retrospectively identified 124 children with post-resection ECoG performed on the margins of resection. ECoG records were scored in a blinded fashion based on presence of frequent spiking. For patients identified as having additional resection based on clinical post-resection ECoG interpretation, these “second-look” ECoG results were re-reviewed for ongoing discharges or completeness of resection. Frequent spike populations were grouped using a standard scoring system into three ranges: 0.1–0.5 Hz, 0.5–1 Hz, >1 Hz. Seizure outcomes were determined at minimum 12-month followup. Results Of 124 patients who met inclusion criteria, 60 (48%) had an identified spike population on post-resection ECoG. Thirty (50%) of these had further resection based on clinical interpretation. Overall, good outcome (ILAE 1) was seen in 56/124 (45%). Completeness of resection of spiking (absence of spiking on initial post-resection ECoG or resolution of spiking after further resection) showed a trend toward good outcome (OR 2.03, p = 0.099). Patients with completeness of resection had good outcome in 41/80 (51%) of cases; patients with continued spikes had good outcome in 15/44 (35%) of cases. Conclusions Post-resection ECoG identifies residual epileptogenic tissue in a significant number of children. Lower frequency or absence of discharges on initial recording showed a trend toward good outcome. Completeness of resection demonstrated on final ECoG recording did not show a significant difference in outcome. This suggests that post-resection discharges represent a prognostic marker rather than a remediable biomarker of the epileptogenic zone in all patients. Resecting residual spike-generating cortex may be beneficial in selected patients, including children with tumors. [ABSTRACT FROM AUTHOR]

Background: Reports have suggested that abnormal cortical excitability may be associated with acute migraines. The present study quantitatively assesses the degree of cortical excitability in chronic migraine as compared to acute migraine and healthy controls within the pediatric population. Methods: We investigated 27 children suffering from chronic migraine, 27 children suffering from acute migraine, and 27 healthy controls using a magnetoencephalography (MEG) system, recording at a sampling rate of 6000 Hz. All groups were age-matched and gender-matched. Neuromagnetic brain activation was elicited by a finger-tapping motor task. The spatiotemporal and spectral signatures of MEG data within a 5-2884 Hz range were analyzed using Morlet wavelet transform and beamformer analyses. Results: Compared with controls, the chronic migraine group showed (1) significantly prolonged latencies of movement-elicited magnetic fields (MEFs) between 5 and 100 Hz; (2) increased spectral power between 100 and 200 Hz, and between 2200 and 2800 Hz; and (3) a higher likelihood of neuromagnetic activation in the ipsilateral sensorimotor cortices, supplementary motor area, and occipital regions. Compared with acute migraine group, chronic migraine patients showed (1) significantly higher odds of having strong MEFs after 150 ms; and (2) significantly higher odds of having neuromagnetic activation from the deep brain areas. Conclusions: Results demonstrated that chronic migraine subjects were not only different from the healthy controls, but also different from acute migraine subjects. The chronification of migraines may be associated with elevated cortical excitability, delayed and spread neural response, as well as aberrant activation from deep brain areas. [ABSTRACT FROM AUTHOR]

Objective The predictive value of intraoperative electrocorticography ( ECoG) in pediatric epilepsy surgery is unknown. In a population of children undergoing ECoG followed typically by invasive extraoperative monitoring ( IEM) and resection, we aimed to determine the relationship between frequent ECoG abnormalities and the seizure onset zone and outcome after resection. Methods We retrospectively identified 103 children with preresection ECoG of sufficient technical quality. ECoG records were scored based on electrode location and frequency, blinded to the seizure-onset zone and outcome. Electrographic seizure and spike locations were identified. Locations of seizures and spike populations were then compared to the location of seizure-onset zone defined by IEM using subdural electrodes and resection margin. Results Electrographic seizures were identified in 11 (11%) of 103 patients. A spike population of one or more was noted in 79 (77%) of 103 patients. In 50 (63%) of 79 patients, spike populations correlated with seizure-onset zone location. The overall surgical outcome was good ( ILAE 1 to 3) in 53 (52%) of 101 patients. Outcome was good in seven (78%) of nine patients when electrographic seizure location was resected. The best outcomes were obtained with resection of both the seizure-onset zone and ECoG abnormalities to include seizures and spike locations (22/33 good outcome, 67%, p = 0.008). There was a significantly better outcome in children with complete resection of ECoG-identified spike populations (14/26, 62% good outcome) compared to when none were resected (4/14, 29%, p = 0.043). Significance Electrographic seizures and frequent spikes are frequently seen on pre-resection ECoG in children. The brain locations corresponding to these discharges are highly concordant with the seizure-onset zone; resection of these regions is correlated with good seizure outcome. Further research is needed to design interventions that increase the reliability of ECoG prediction of the epileptogenic zone and obviate the need for IEM. [ABSTRACT FROM AUTHOR]

Objective The abnormality of intrinsic brain activity in autism spectrum disorders (ASDs) is still inconclusive. Contradictory results have been found pointing towards hyper-activity or hypo-activity in various brain regions. The present research aims to investigate the spatial and spectral signatures of aberrant brain activity in an unprecedented frequency range of 1–2884 Hz at source levels in ASD using newly developed methods. Materials and methods Seven ASD subjects and age- and gender-matched controls were studied using a high-sampling rate magnetoencephalography (MEG) system. Brain activity in delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (12–30 Hz), low gamma (30–55 Hz), high gamma (65–90 Hz), ripples (90–200 Hz), high-frequency oscillations (HFOs, 200–1000 Hz), and very high-frequency oscillations (VHFOs, 1000–2884 Hz) was volumetrically localized and measured using wavelet and beamforming. Results In comparison to controls, ASD subjects had significantly higher odds of alpha activity (8–12 Hz) in the sensorimotor cortex (mu rhythm), and generally high-frequency activity (90–2884 Hz) in the frontal cortex. The source power of HFOs (200–1000 Hz) in the frontal cortex in ASD was significantly elevated as compared with controls. Conclusion The results suggest that ASD has significantly altered intrinsic brain activity in both low- and high-frequency ranges. Increased intrinsic high-frequency activity in the frontal cortex may play a key role in ASD. [ABSTRACT FROM AUTHOR]

Objective evaluation of language function is critical for children with intractable epilepsy under consideration for epilepsy surgery. The purpose of this preliminary study was to evaluate word recognition in children with intractable epilepsy by using magnetoencephalography (MEG). Ten children with intractable epilepsy (M/F 6/4, mean ± SD 13.4 ± 2.2 years) were matched on age and sex to healthy controls. Common nouns were presented simultaneously from visual and auditory sensory inputs in “match” and “mismatch” conditions. Neuromagnetic responses M1, M2, M3, M4, and M5 with latencies of ~100 ms, ~150 ms, ~250 ms, ~350 ms, and ~450 ms, respectively, elicited during the “match” condition were identified. Compared to healthy children, epilepsy patients had both significantly delayed latency of the M1 and reduced amplitudes of M3 and M5 responses. These results provide neurophysiologic evidence of altered word recognition in children with intractable epilepsy. [ABSTRACT FROM AUTHOR]

Summary Introduction This study describes development of a novel language mapping approach using high-γ modulation in electrocorticograph (ECoG) during spontaneous conversation, and its comparison with electrical cortical stimulation (ECS) in childhood-onset drug-resistant epilepsy. Methods Patients undergoing invasive pre-surgical monitoring and able to converse with the investigator were eligible. ECoG signals and synchronized audio were acquired during quiet baseline and during natural conversation between investigator and the patient. Using Signal Modeling for Real-time Identification and Event Detection (SIGFRIED) procedure, a statistical model for baseline high-γ (70–116 Hz) power, and a single score for each channel representing the probability that the power features in the experimental signal window belonged to the baseline model, were calculated. Electrodes with significant high-γ responses (HGS) were plotted on the 3D cortical model. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), and classification accuracy were calculated compared to ECS. Results Seven patients were included (4 males, mean age 10.28 ± 4.07 years). Significant high-γ responses were observed in classic language areas in the left hemisphere plus in some homologous right hemispheric areas. Compared with clinical standard ECS mapping, the sensitivity and specificity of HGS mapping was 88.89% and 63.64%, respectively, and PPV and NPV were 35.29% and 96.25%, with an overall accuracy of 68.24%. HGS mapping was able to correctly determine all ECS+ sites in 6 of 7 patients and all false—sites (ECS+, HGS− for visual naming, n = 3) were attributable to only 1 patient. Conclusions This study supports the feasibility of language mapping with ECoG HGS during spontaneous conversation, and its accuracy compared to traditional ECS. Given long-standing concerns about ecological validity of ECS mapping of cued language tasks, and difficulties encountered with its use in children, ECoG mapping of spontaneous language may provide a valid alternative for clinical use. [ABSTRACT FROM AUTHOR]

Objectives Magnetoencephalography ( MEG) is used to guide intracranial electroencephalography ( ICEEG) monitoring and determine areas for resection. The purpose of this retrospective cross-sectional study was to report our experience using dipole modeling/dipole scanning, current density reconstructions, and beam-forming methods in a large cohort of pediatric patients with intractable epilepsy. Methods Source localization results for each algorithm and seizure-onset zone, defined by ICEEG, were described by three blinded reviewers according to five location criteria. The accuracy of each algorithm was then compared to ICEEG. The relationships between the accuracy of these algorithms (discordant, lobar concordant, sublobar concordant) and long-term seizure outcome was calculated using positive and negative predictive values. Results Thirty-two patients (mean age ± SD, 10.8 ± 5 years) were included in this retrospective review. No algorithms had sublobar concordance with ICEEG in all patients, including when algorithms were grouped by type (dipole modeling/dipole scanning, current density reconstruction, beam forming). Synthetic aperture magnetometry ( SAM) with excess kurtosis tended to be the most accurate, but there were no significant differences between algorithms. When comparing the source modeling with ICEEG findings, significantly more patients with a seizure-free outcome were found to have lobar or sublobar concordance of multiple signal classification ( MUSIC) (61.1%) and standardized low resolution brain electromagnetic tomography (s LORETA) (52.9%). Positive predictive values were highest for MUSIC (61.9%) and equivalent current dipole ( ECD) (57.1%). Negative predictive values were highest for SAM( g2)- VS (83%), minimum norm estimate ( MNE) (75%), MUSIC (73.7%), and ECD (73.5%). Significance This study describes the use of multiple MEG source estimation techniques and demonstrates that all algorithms have similar rates of concordance with ICEEG. Also, the concordance or discordance of MUSIC with ICEEG was the best predictor of long-term seizure outcome. [ABSTRACT FROM AUTHOR]

Objective The aim of this study was to determine the frequency-dependent, spatiotemporal involvement of corticothalamic networks to the generation of absence seizures. Methods Magnetoencephalography recordings were obtained in 12 subjects (44 seizures) with untreated childhood absence seizures. Time-frequency analysis of each seizure was performed to determine bandwidths with significant power at ictal onset. Source localization was then completed to determine brain regions contributing to generalized spike and wave discharges seen on electroencephalogram. Results Significant power in the time-frequency analysis was seen within 1 to 20Hz, 20 to 70Hz, and 70 to 150Hz bandwidths. Source localization revealed that sources localized to the frontal cortex similarly for the low- and gamma-frequency bandwidths, whereas at the low-frequency bandwidth (3-20Hz) significantly more sources localized to the parietal cortex (odds ratio [OR] = 16.7). Cortical sources within the high-frequency oscillation (HFO) bandwidth (70-150Hz) localized primarily to the frontal region compared to the parietal (OR = 7.32) or temporal (OR = 2.78) areas. Interpretation Neuromagnetic activity within frontal and parietal cortical regions provides further confirmation of hemodynamic changes reported using functional magnetic resonance imaging that have been associated with absence seizures. The frequency-dependent nature of these networks has not previously been reported, and the presence of HFOs during absence seizures is a novel finding. Co-occurring frontal and parietal corticothalamic networks may interact to produce a pathological state that contributes to the generation of spike and wave discharges. The clinical and pathophysiological implications of HFOs within the frontal cortical region are unclear and should be further investigated. Ann Neurol 2014;76:558-567 [ABSTRACT FROM AUTHOR]

Highlights: [•] Timing of brain activity during absence seizures is unclear. [•] MEG was used to determine corticothalamic brain activity during absence seizures. [•] Before absence seizure onset most activity was seen in frontal cortex and thalamus. [•] MEG can be used to measure corticothalamic activity with high temporal resolution. [•] Focal ictal activity occurs during “generalized” childhood absence seizures. [Copyright &y& Elsevier]

Abstract: Patients with obsessive-compulsive disorder (OCD) often report sensory intolerances which may lead to significant functional impairment. This study used auditory evoked fields (AEFs) to address the question of whether neural correlates of sensory auditory information processing differ in youth with OCD compared with healthy comparison subjects (HCS). AEFs, recorded with a whole head 275-channel magnetoencephalography system, were elicited in response to binaural auditory stimuli from 10 pediatric subjects with OCD (ages 8–13, mean 11 years, 6 males) and 10 age- and gender-matched HCS. Three major neuromagnetic responses were studied: M70 (60–80ms), M100 (90–120ms), and M150 (130–190ms). When compared with HCS, subjects with OCD demonstrated delayed latency of the M100 response. In subjects with OCD the amplitude of the M100 and M150 responses was significantly greater in the right hemisphere compared with the left hemisphere. Current results suggest that when compared with HCS, subjects with OCD have altered auditory information processing, evident from the delayed latency of the M100 response, which is thought to be associated with the encoding of physical stimulus characteristics. Interhemispheric asymmetry with increased M100 and M150 amplitudes over the right hemisphere compared with the left hemisphere was found in young OCD subjects. These results should be interpreted with caution due to the high variability rate of responses in both HCS and OCD subjects, as well as the possible effect of medication in OCD subjects. [Copyright &y& Elsevier]

Purpose Implantation of subdural grids and invasive electroencephalography (EEG) monitoring is important to define the ictal-onset zone and eloquent cortex in selected patients with medically refractory epilepsy. The objective of this systematic review is to summarize data about adverse events related to this procedure. Methods English-language studies published up to July 2012, reporting such adverse events were reviewed. Outcome measures included demographic variables; surgical protocol including number of subdural electrodes implanted per patient, duration of monitoring, antibiotic, and steroid prophylaxis; and adverse events. Key Findings Twenty-one studies were identified including a total of 2,542 patients. The reported mean number of electrodes per patient and duration of monitoring varied from 52 to 95 and 5 to 17 days, respectively. There is a trend toward more uniform use of antibiotics and steroids in the perioperative period. Neurologic infections (pooled prevalence 2.3%, 95% confidence interval 1.5-3.1), superficial infections (3.0%, 1.9-4.1), intracranial hemorrhage (4.0%, 3.2-4.8), and elevated intracranial pressure (2.4%, 1.5-3.3) were found to be the most common adverse events. Up to 3.5% of patients required additional surgical procedure(s) for management of these adverse events. Increased number of electrodes (≥67) was found to be independently associated with increased incidence of adverse events. Significance Although providing critical information for patients with medically refractory epilepsy, subdural grids implantation and invasive EEG monitoring entails risks of infection, hemorrhage, and elevated intracranial pressure. The prevalence estimates, likely to be conservative due to selective reporting, are expected to be helpful in counseling patients. [ABSTRACT FROM AUTHOR]

Purpose: Intracranial electroencephalography (EEG) is performed as part of an epilepsy surgery evaluation when noninvasive tests are incongruent or the putative seizure-onset zone is near eloquent cortex. Determining the seizure-onset zone using intracranial EEG has been conventionally based on identification of specific ictal patterns with visual inspection. High-frequency oscillations (HFOs, >80 Hz) have been recognized recently as highly correlated with the epileptogenic zone. However, HFOs can be difficult to detect because of their low amplitude. Therefore, the prevalence of ictal HFOs and their role in localization of epileptogenic zone on intracranial EEG are unknown. Methods: We identified 48 patients who underwent surgical treatment after the surgical evaluation with intracranial EEG, and 44 patients met criteria for this retrospective study. Results were not used in surgical decision making. Intracranial EEG recordings were collected with a sampling rate of 2,000 Hz. Recordings were first inspected visually to determine ictal onset and then analyzed further with time-frequency analysis. Forty-one (93%) of 44 patients had ictal HFOs determined with time-frequency analysis of intracranial EEG. Key Findings: Twenty-two (54%) of the 41 patients with ictal HFOs had complete resection of HFO regions, regardless of frequency bands. Complete resection of HFOs (n = 22) resulted in a seizure-free outcome in 18 (82%) of 22 patients, significantly higher than the seizure-free outcome with incomplete HFO resection (4/19, 21%). Significance: Our study shows that ictal HFOs are commonly found with intracranial EEG in our population largely of children with cortical dysplasia, and have localizing value. The use of ictal HFOs may add more promising information compared to interictal HFOs because of the evidence of ictal propagation and followed by clinical aspect of seizures. Complete resection of HFOs is a favorable prognostic indicator for surgical outcome. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Our study is to investigate somatosensory dysfunction in children with spastic cerebral palsy (CP) using magnetoencephalography (MEG) and synthetic aperture magnetometry (SAM). Methods: Six children with spastic CP and six age- and gender-matched typically developing children were studied using a 275-channel MEG system while their left and right index fingers were stimulated in random order. The latency and amplitude of somatosensory evoked magnetic fields were analyzed at sensor level. The patterns of high-gamma oscillations were investigated with SAM at source level. Results: In comparison to the children with typical development, the latency of the first response of somatosensory evoked magnetic fields (SEFs) in the children with spastic CP was significantly delayed (p <0.05). High-gamma oscillations were identified in the somatosensory cortex in both children with CP and typical developing children. Interestingly, children with spastic CP had significantly higher incidence of ipsilateral activation in the somatosensory cortex following right and left finger stimulation, compared to typically developing children (p =0.05). Conclusion: The results suggest that children with spastic CP have a measurable delay of SEFs and high-gamma oscillations. The high rates of ipsilateral cortical activation imply the impairments of functional lateralization in the developing brain. This is the first MEG study to demonstrate abnormal high-gamma oscillations of somatosensory cortices representing the finger in children with spastic CP. [Copyright &y& Elsevier]

Summary: Purpose: Magnetoencephalography (MEG) has been shown a useful diagnostic tool for presurgical evaluation of pediatric medically intractable partial epilepsy as MEG source localization has been shown to improve the likelihood of seizure onset zone (SOZ) sampling during subsequent evaluation with intracranial EEG (ICEEG). We investigated whether ictal MEG onset source localization further improves results of interictal MEG in defining the SOZ. Methods: We identified 20 pediatric patients with one habitual seizure during MEG recordings between October 2007 and April 2011. MEG was recorded with sampling rates of 600Hz and 4000Hz for 10 and 2min respectively. Continuous head localization (CHL) was applied. Source localization analyses were applied using multiple algorithms, both at the beginning of ictal onset and for interictal MEG discharges. Ictal MEG onsets were identified by visual inspection and power spectrum using short-time Fourier transform (STFT). Source localizations were compared with ICEEG, surgical procedure and outcome. Key findings: Eight patients met all inclusion criteria. Five of the 8 patients (63%) had concordant ictal MEG onset source localization and interictal MEG discharge source localizations in the same lobe, but the source of ictal MEG onset was closer to the SOZ defined by ICEEG. Significance: Although the capture of seizures during MEG recording is challenging, the source localization for ictal MEG onset proved to be a useful tool for presurgical evaluation in our pediatric population with medically intractable epilepsy. [Copyright &y& Elsevier]

Abstract: Objective: This study aimed to use magnetoencephalography (MEG) to examine the question of whether Mandarin-English bilingual speakers recruit the same cortical areas or develop distinct language-specific networks without overlaps for word processing. Methods: Eight healthy Mandarin-English bilingual adults and eight healthy English monolingual adults were scanned while single-word paradigms were audio-visually presented. Results: Our results showed significantly stronger beta-band power suppression in the right inferior parietal lobe (IPL) covering the supramarginal gyrus (BA 40) and angular gyrus (BA 39) for bilinguals when processing Mandarin versus English. Moreover, there were no significant differences between bilinguals and monolinguals in the left inferior frontal cortex (LIFC, BA 44/45) when both were processing their first language. Conclusions: These results support the view that Mandarin-English bilinguals have a shared neural system for word processing in both the first and second language, which is highly similar to monolinguals’, but with stronger right hemisphere involvement. Significance: To our knowledge, this is the first MEG study to investigate the spatio-temporal and frequency characteristics between bilinguals and monolinguals, which provides us a new angle to better understand the language system in bilinguals’ and monolingual’s brain. [Copyright &y& Elsevier]

Acute migraine could be associated with neurophysiological and cognitive changes. This study evaluates the neurophysiological changes in auditory information processing in adolescents with acute migraine by means of magnetoencephalography. The multifeature sound mismatch negativity (MMN) paradigm was used to study nine adolescents with an acute migraine and nine age- and gender-matched healthy controls. Latencies and amplitudes of M100, M150, M200, and MMN m responses were evaluated. Migraine subjects had smaller M150 amplitudes than healthy subjects. The latencies of MMN m response for the frequency change were delayed in both hemispheres in migraine subjects, as compared with healthy controls. Our results indicate that the function of neural substrates, responsible for different stages of auditory information processing, is impaired during the acute migraine. The identification of underlying cortical dysfunction during an acute migraine can lead to future identification of neurophysiological biomarkers for studying acute migraine and response to treatment. [ABSTRACT FROM AUTHOR]

Abstract: Background and Purpose: The widespread propagation of synchronized neuronal firing in seizure disorders may affect cortical and subcortical brain regions. Diffusion tensor imaging (DTI) can noninvasively quantify white matter integrity. The purpose of this study was to investigate the abnormal changes of white matter in children and adolescents with focal temporal lobe epilepsy (TLE) using DTI. Materials and Methods: Eight patients with clinically diagnosed TLE and eight age- and sex-matched healthy controls were studied. DTI images were obtained with a 3-T magnetic resonance imaging scanner. The epileptic foci were localized with magnetoencephalography. Fractional anisotropy (FA), mean diffusivity (MD), parallel (λ||) and perpendicular (λ⊥) diffusivities in the genu of the corpus callosum, splenium of the corpus callosum (SCC), external capsule (EC), anterior limbs of the internal capsule (AIC), and the posterior limbs of the internal capsule (PIC) were calculated. The DTI parameters between patients and controls were statistically compared. Correlations of these DTI parameters of each selected structure with age of seizure onset and duration of epilepsy were analysed. Results: In comparison to controls, both patients'' seizure ipsilateral and contralateral had significantly lower FA in the AIC; PIC and SCC and higher MD, λ|| and λ⊥ in the EC, AIC, PIC and SCC. The MD, λ|| and λ⊥ were significantly correlated with age of seizure onset in the EC and PIC. λ|| was significantly correlated with the duration of epilepsy in the EC and PIC. Conclusion: The results of the present study indicate that children and adolescents with TLE had significant abnormalities in the white matter in the hemisphere with seizure foci. Furthermore, these abnormalities may extend to the other brain hemisphere. The age of seizure onset and duration of epilepsy may be important factors in determining the extent of influence of children and adolescents TLE on white matter. [Copyright &y& Elsevier]

Summary: Purpose: We aimed to determine the changes in neural correlates of auditory information processing such as auditory detection, encoding, and sensory discrimination in pediatric patients with intractable epilepsy. Methods: In this magnetoencephalography (MEG) study, 10 patients and 10 age- and gender-matched healthy controls were investigated with the multi-feature mismatch negativity (MMN) paradigm. Latencies and amplitudes of M100, M150, M200, and MMN event-related fields were evaluated. Results: All event-related fields in response to standard stimuli (M100, M150 and M200) and responses to occasional five deviant sounds, deviating from the standard stimuli either in duration, frequency, intensity, location, or by including a silent gap were reduced in amplitude in epilepsy patients compared with healthy controls. Conclusions: Our study suggests that auditory information processing is impaired in patients with drug-resistant epilepsy, being evident both in stimulus feature encoding (as reflected by changes of early event-related components, e.g., M100) and in cortical sound discrimination (as reflected by MMNm). The neural changes involving diminished M100 as well as MMNms for all five deviant sound types suggest wide-spread auditory information processing impairments in these patients. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, there has been a growing interest on the role of gamma band (>30Hz) neural oscillations in motor control, although the function of this activity in motor control is unknown clearly. With the goal of discussing the high frequency sources non-invasively and precisely during unilateral index finger movement, we investigated gamma band oscillations in 20 right-handed normal adults with magnetoencephalography (MEG). The results showed that gamma band activity appeared only during finger movement. Nineteen subjects displayed consistently contralateral event-related synchronization (C-ERS) within high gamma band (70–150Hz) in primary motor cortex (M1) of both hemispheres. Interestingly, 15 subjects displayed ipsilateral event-related desynchronization (I-ERD) and C-ERS within broad gamma band (30–150Hz). The locations of the broad gamma band I-ERD and C-ERS revealed hemispherical symmetry in M1. These findings demonstrate that there are consistent high gamma C-ERS and inconsistent low gamma I-ERD during a simple finger movement in the motor cortex. This study provides new evidence for the use of high gamma frequency oscillations as biomarkers in the analyses of functional brain activity and the localization of the motor cortex. [ABSTRACT FROM AUTHOR]

The discontinuous patterns in neonatal magnetoencephalographic (MEG) data are quantified with a novel Hilbert phase (HP) based approach. The expert neurologists' scores were used as the gold standard. The performance of this approach was analyzed using a receiver operating characteristic (ROC) curve, and it was compared with two other approaches, namely spectral ratio (SR) and discrete wavelet transform (DWT) that have been proposed for the detection of discontinuous patterns in neonatal EEG. The area under the ROC curve (AUC) was used as a performance measure. AUCs obtained for SR, HP, and DWT were 0.87, 0.80, and 0.56, respectively. Although the performance of HP was lower than SR, it carries information about the frequency content of the signal that helps to distinguish brain patterns from artifacts such as cardiac residuals. Based on this property, the HP approach was extended to fetal MEG data. Further, using the frequency property of the HP approach, burst duration and interburst interval were computed for the discontinuous patterns detected and they are in agreement with reported values. [ABSTRACT FROM AUTHOR]

Abstract: Recent studies have found that the brain generates very fast oscillations. The objective of the present study was to investigate the spectral, spatial and coherent features of high-frequency brain oscillations in the developing brain. Sixty healthy children and 20 healthy adults were studied using a 275-channel magnetoencephalography (MEG) system. MEG data were digitized at 12,000 Hz. The frequency characteristics of neuromagnetic signals in 0.5–2000 Hz were quantitatively determined with Morlet wavelet transform. The magnetic sources were volumetrically estimated with wavelet-based beamformer at 2.5 mm resolution. The neural networks of endogenous brain oscillations were analyzed with coherent imaging. Neuromagnetic activities in 8–12 Hz and 800–900 Hz were found to be the most reliable frequency bands in healthy children. The neuromagnetic signals were localized in the occipital, temporal and frontal cortices. The activities in the occipital and temporal cortices were strongly correlated in 8–12 Hz but not in 800–900 Hz. In comparison to adults, children had brain oscillations in intermingled frequency bands. Developmental changes in children were identified for both low- and high-frequency brain activities. The results of the present study suggest that the development of the brain is associated with spatial and coherent changes of endogenous brain activities in both low- and high-frequency ranges. Analysis of high-frequency neuromagnetic oscillation may provide novel insights into cerebral mechanisms of brain function. The noninvasive measurement of neuromagnetic brain oscillations in the developing brain may open a new window for analysis of brain function. [Copyright &y& Elsevier]

Background: Magnetoencephalography (MEG) is increasingly used in the presurgical evaluation of pediatric seizure patients. Many pediatric patients require sedation or anesthesia to tolerate these exams. However, the available literature on anesthetic management in this population is very limited. Methods: We retrospectively reviewed the records of all patients who underwent MEG scanning at our institution with regard to the interaction of anesthetic management and quality of scan data. Results: High-dose propofol infusions (≥200 μg·kg−1·min−1) were associated with high frequency artifacts that interfered with the identification of epileptiform discharges. Lower-dose propofol infusions (≤100 μg·kg−1·min−1) did not produce artifacts but required co-administration of fentanyl to prevent patient motion. Dexmedetomidine infusions were not associated with signal artifacts and prevented patient motion very well in our initial patients and became our standard technique. Conclusion: In our experience, dexmedetomidine infusions are preferable to propofol-based techniques for pediatric MEG scans due to the absence of adverse effect on interictal activity. [ABSTRACT FROM AUTHOR]

Abstract: Hemispheric specialization or asymmetry in higher brain functions such as language is well accepted. This study was designed to quantitatively determine if the hemispheric asymmetry is measurable in the somatosensory system. Twenty-two participants were studied with magnetoencephalography (MEG) while their left and right index fingers were stimulated in randomized order. The finger representation in the cortex was volumetrically localized using a wavelet based beamformer. The strength of functional activity was estimated with an intensity volume while the waveforms of the virtual sensors were computed with a virtual sensor placed in the center of localized finger area. The results showed that the latency of the first identifiable response evoked by left finger stimulation was significantly shorter than that evoked by right finger stimulation (p <0.05). The left somatosensory cortex generated higher frequency neuromagnetic signals than did the right somatosensory cortex (p <0.05). Moreover, the volume of neuromagnetic activation elicited by right finger stimulation was significantly larger than that elicited by left finger stimulation in males (p <0.001). The neuromagnetic activation revealed by virtual sensors was more consistent than that revealed by physical sensors across participants. We conclude that neuromagnetic activities in the left and right somatosensory cortices have significant differences in terms of response latency, oscillation frequency and activation volume in high-frequency neuromagnetic signals. An investigation of the hemispheric specific features of neuromagnetic activation in the somatosensory cortex lays a foundation for the study of psychophysiologic asymmetries in the brain. [Copyright &y& Elsevier]

Background: As magnetoencephalography (MEG) is of increasing utility in the assessment of deficits and development delays in brain disorders in pediatrics, it becomes imperative to fully understand the functional development of the brain in children. Methodology: The present study was designed to characterize the developmental patterns of auditory evoked magnetic responses with respect to age and gender. Sixty children and twenty adults were studied with a 275-channel MEG system. Conclusions: Three main responses were identified at approximately 46 ms (M50), 71 ms (M70) and 106 ms (M100) in latency for children. The latencies of M70 and M100 shortened with age in both hemispheres; the latency of M50 shortened with age only in the right hemisphere. Analysis of developmental lateralization patterns in children showed that the latency of the right hemispheric evoked responses shortened faster than the corresponding left hemispheric responses. The latency of M70 in the right hemisphere highly correlated to the age of the child. The amplitudes of the M70 responses increased with age and reached their peaks in children 12-14 years of age, after which they decreased with age. The source estimates for the M50 and M70 responses indicated that they were generated in different subareas in the Heschl's gyrus in children, while not localizable in adults. Furthermore, gender also affected developmental patterns. The latency of M70 in the right hemisphere was proposed to be an index of auditory development in children, the modeling equation is 85.72-1.240xAge (yrs). Our results demonstrate that there is a clear developmental pattern in the auditory cortex and underscore the importance of M50 and M70 in the developing brain. [ABSTRACT FROM AUTHOR]

Abstract: The present study aimed to investigate whether magnetoencephalography (MEG) information could result in the detection of subtle anatomical abnormalities at re-review of conventional magnetic resonance imaging (MRI) by a new MEG guided post-image processing technology. Eight paediatric patients with tuberous sclerosis complex (TSC) confirmed by clinical and neuroimaging findings were retrospectively studied. MEG data were recorded using a whole-cortex CTF OMEGA system. Irritable zones were localized using synthetic aperture magnetometry (SAM). A new MEG guided post-image processing technology was employed to identify the “small tubers” found only by SAM. MRI detected 42 tubers for the 8 patients. SAM found 51 irritable zones, and 31 out of the 51 zones were around tubers (31/42, 74%). Among 20 of the 51 zones, which did not have corresponding MRI tubers, we detected 14 subtle lesions in total; 9 of 14 were found in low frequency band (1–35 Hz); 5 of 14 were found in high frequency band (35–60 Hz and 60–120 Hz). SAM appeared to offer more detection of irritable zones and beneficial frequency descriptions. The majority of these irritable zones detected only by SAM were indicated to be small tubers by MEG guided post-image processing technology. This technology might be a powerful tool in the detection of subtle structural abnormalities. [Copyright &y& Elsevier]

Summary: Purpose: Children with epilepsy have high rates of behavior problems. The purpose was to describe prospectively the association of seizures and behavior problems in children with new-onset seizures. Methods: Subjects were 224 children with new-onset seizures (aged 4–14 years) and 159 siblings (4–18 years). Caregiver's ratings of the behavior were collected 4 times: at baseline, and at 6, 12, and 24 months. During the 2-year period, 163 (73%) children had at least one additional seizure, and 61 (27%) had none. Data were analyzed by using repeated measures analysis of variance both with and without covariates [site, age, gender, race, caregiver education (years), and seizure medications]. Results: On average, children had higher CBCL Total and Internalizing Behavior Problems scores across all times when experiencing recurrent seizures than when not experiencing recurrent seizures (Total Problems, p = 0.041, controlling for demographics and seizure medications). Siblings had significantly lower Total and Internalizing Problems scores than both children experiencing (Total Problems adjusting for covariates, p = 0.0001) and not experiencing recurrent seizures (p = 0.0004). Externalizing Problems scores were not significantly different among children with recurring seizures, children without recurring seizures, and siblings. Conclusions: Recurrent seizures significantly predicted behavior problems very early in the course of a seizure condition, even when key child, demographic, and seizure variables were controlled. Explanations for these findings include the possibilities that both seizures and behavior problems are caused by an underlying neurological disorder, that seizures per se disrupt behavior, or that children have negative psychological responses to seizure activity. [ABSTRACT FROM AUTHOR]

The study objective was to determine whether short-term serial magnetoencephalographic (MEG) measurements would increase the odds in favor of obtaining fetal auditory evoked responses in normal fetuses. The recordings were performed in two phases using the newly developed 151-channel fetal MEG system, superconducting quantum interference device array for reproductive assessment. Ten pregnant subjects with gestational ages ranging from 30–35 weeks were recruited to participate. Daily recordings were performed over a minimum of 3 days during 1 week of gestation and repeated in the same subjects between 36 and 40 weeks gestation. In 80% of subjects, auditory evoked responses were detected at least once. In healthy fetuses, serial recordings over a short span of time increased the rate of detecting fetal evoked response. [Copyright &y& Elsevier]

Conclusions. Children with previously unrecognized seizures are already at increased risk for behavior problems at the time of their first recognized seizure. These findings are consistent with the hypothesis that in some children, epilepsy is a pervasive condition that includes both seizures and behavioral problems. Pediatrics 2001;107:115-122; children, first seizures, epilepsy, behavior problems, siblings. [ABSTRACT FROM AUTHOR]

We investigated the feasibility of recording visual evoked brain activity in the human fetus by use of non-invasive magnetoencephalography (MEG). Each recording lasted 6 min and consisted of a sequence of 180 flashes with 33 ms duration delivered 2 s apart over the maternal abdomen. Four of ten fetuses included showed a response; the ranges of amplitude and latency of peak response were 15-30 x 10(-15) Tesla and 180-390 ms, respectively. Six fetuses showed no discernible response. With improvement, this method could aid in the testing of fetal neurological status throughout pregnancy. [ABSTRACT FROM AUTHOR]

We investigated the feasibility of recording visual evoked brain activity in the human fetus by use of non-invasive magnetoencephalography (MEG). Each recording lasted 6 min and consisted of a sequence of 180 flashes with 33 ms duration delivered 2 s apart over the maternal abdomen. Four of ten fetuses included showed a response; the ranges of amplitude and latency of peak response were 15-30310[-15] Tesla and 180-390 ms, respectively. Six fetuses showed no discernible response. With improvement, this method could aid in the testing of fetal neurological status throughout pregnancy. [ABSTRACT FROM AUTHOR]