Low-resolution Electromagnetic Tomography Analysis Research Articles

The intention to conceal activates the right prefrontal cortex: an event-related potential study.

Recent studies on deception have shown that a late positive potential (LPP), a component of event-related brain potentials, is elicited when a participant wishes to conceal recognition of the eliciting stimulus. The LPP occurs about 500 ms after stimulus onset and has an occipital scalp distribution with concurrent negativity at frontal sites. The present study investigated the cortical sources of the LPP associated with the intention to conceal. Standardized low-resolution electromagnetic tomography analysis was applied on previously published concealment-related LPP data (Matsuda, Nittono, and Ogawa, 2013, N=30). The cortical sources of the LPP were estimated in the right middle frontal gyrus and the right inferior frontal gyrus, which fits well with the findings of fMRI studies. Previous research suggests that activities in the middle frontal gyrus and the right inferior frontal gyrus are associated with cognitive control and that greater relative right than left frontal activities are associated with withdrawal motivation. On the basis of these findings, it is concluded that the LPP may reflect cognitive control with withdrawal motivation that is recruited by the participants' goal of concealing their recognition and avoiding disclosure. A positive potential at occipital sites can be a sign of the activation in the prefrontal cortex.

Anodal transcranial direct current stimulation (tDCS) increases frontal–midline theta activity in the human EEG: A preliminary investigation of non-invasive stimulation

Rhythmical brain activity in the range between four and eight Hz acquired over frontal–midline EEG recording sites – so called frontal–midline theta activity – is regarded as one of the most prominent neural signatures of sustained attention. It is reported to parametrically increase with cognitive load and is thought to be generated in medial prefrontal cortex. Here we explored the possibility of using anodal transcranial direct current stimulation over frontal sites to enhance frontal–midline theta activity and to increase sustained attention performance. We used a small preliminary sample to test a novel direct current stimulation electrode configuration by which we were able to significantly increase frontal–midline theta amplitude in a resting condition after the end of the stimulation period. Using standardised low resolution electromagnetic tomography analysis the effect in the surface EEG was localised to right prefrontal and left medial prefrontal brain areas. Transcranial direct current stimulation did, however, not have any impact on behavioural performance during a sustained attention task. This most likely was due to a very fast washout of the stimulation’s after effect on theta activity. Although these are only preliminary results from a rather small sample, this study demonstrates that transcranial direct current stimulation can be used to rather selectively enhance frontal–midline theta amplitude.

Interhemispheric Asymmetries and Theta Activity in the Rostral Anterior Cingulate Cortex as EEG Signature of HIV-Related Depression: Gender Matters.

Resting EEGs of 40 people living with HIV (PLWH) on long-term antiretroviral treatment were examined for z-scored deviations from a healthy control (normative database) to examine the main and interaction effects of depression and gender. Regions of interest were frontal (alpha) and central (all bands) for interhemispheric asymmetries in quantitative EEGs and theta in the rostral anterior cingulate cortex (rACC) in low-resolution electromagnetic tomography (LORETA). Z-scored normed deviations of depressed PLWH, compared with nondepressed, showed right-dominant interhemispheric asymmetries in all regions. However, after adjusting for multiple testing, significance remained only central for theta, alpha, and beta. Reversed (left-dominant) frontal alpha asymmetry is a potential EEG marker of depression in the HIV negative population that was not reversed in depressive PLWH; however, corresponding with extant literature, gender had an effect on the size of frontal alpha asymmetry. The LORETA analysis revealed a trending interactional effect of depression and gender on theta activity in the rACC in Brodmann area 32. We found that compared to men, women had greater right-dominant frontal alpha-asymmetry and elevated theta activity in voxels of the rACC, which may indicate less likelihood of depression and a higher likelihood of response to antidepressants. In conclusion, subtle EEG deviations, such as right-dominant central theta, alpha, and beta asymmetries and theta activity in the rACC may mark HIV-related depressive symptoms and may predict the likelihood of response to antidepressants but gender effects need to be taken into account. Although this study introduced the use of LORETA to examine the neurophysiological correlates of negative affect in PLWH, further research is needed to assess the utility of this tool in diagnostics and treatment monitoring of depression in PLWH.

Quantitative Support for Convergence of Intrinsic Energies from Applied Magnetic Fields and “Noise” Fluctuations of Newton’s Gravitational Value within the Human Brain

When the energy within the mass of the human brain that is associated with the intrinsic range in fluctuations of the Gravitational Constant (G) is set equal to the energy from a magnetic field (B) within the cerebral volume and solved for B, a value in the order of 20 to 50 nT is obtained. Quantitative Electroencephalographic (QEEG) and sLORETA (Low Resolution Electromagnetic Tomography) analyses of cerebral cortical activity during exposure to a range of applied rotating, frequency-modulated, transcerebral (between the two temporal lobes) magnetic fields between < 1 nT and 7000 nT while volunteers sat within a darkened, quiet chamber were completed. There was marked enhancement of power within the 4 Hz to 10 Hz band within the right caudal (cuneus) hemisphere while the ~5 to 20 nT averaged strength magnetic fields were applied but no significant responses at lesser or greater intensities. These results suggest that a physical process coupled to the source of the fluctuation (~10-15 m3·kg-1·s-2) in G may interact with right hemispheric activity within the range at which gravity waves have been estimated to interact with Schumann frequencies generated between the earth and ionosphere.

Quantitative Support for Convergence of Intrinsic Energies from Applied Magnetic Fields and “Noise” Fluctuations of Newton’s Gravitational Value within the Human Brain

When the energy within the mass of the human brain that is associated with the intrinsic range in fluctuations of the Gravitational Constant (G) is set equal to the energy from a magnetic field (B) within the cerebral volume and solved for B, a value in the order of 20 to 50 nT is obtained. Quantitative Electroencephalographic (QEEG) and sLORETA (Low Resolution Electromagnetic Tomography) analyses of cerebral cortical activity during exposure to a range of applied rotating, frequency-modulated, transcerebral (between the two temporal lobes) magnetic fields between < 1 nT and 7000 nT while volunteers sat within a darkened, quiet chamber were completed. There was marked enhancement of power within the 4 Hz to 10 Hz band within the right caudal (cuneus) hemisphere while the ~5 to 20 nT averaged strength magnetic fields were applied but no significant responses at lesser or greater intensities. These results suggest that a physical process coupled to the source of the fluctuation (~10-15 m3·kg-1·s-2) in G may interact with right hemispheric activity within the range at which gravity waves have been estimated to interact with Schumann frequencies generated between the earth and ionosphere.

Prediction of Treatment Response and the Effect of Independent Component Neurofeedback in Obsessive-Compulsive Disorder: A Randomized, Sham-Controlled, Double-Blind Study

Aims: The goal of this study was to assess the effect of independent component neurofeedback (NFB) on EEG and clinical symptoms in patients with obsessive-compulsive disorder (OCD). Subsequently, we explored predictors of treatment response and EEG correlates of clinical symptoms. Methods: In a randomized, double-blind, parallel design, 20 inpatients with OCD underwent 25 sessions of NFB or sham feedback (SFB). NFB aimed at reducing EEG activity in an independent component previously reported abnormal in this diagnosis. Resting-state EEG recorded before and after the treatment was analyzed to assess its posttreatment changes, relationships with clinical symptoms and treatment response. Results: Overall, clinical improvement in OCD patients was not accompanied by EEG change as assessed by standardized low-resolution electromagnetic tomography and normative independent component analysis. Pre- to posttreatment comparison of the trained component and frequency did not yield significant results; however, in the NFB group, the nominal values at the downtrained frequency were lower after treatment. The NFB group showed significantly higher percentage reduction of compulsions compared to the SFB group (p = 0.015). Pretreatment higher amount of delta (1-6 Hz) and low alpha oscillations as well as a lower amount of high beta activity predicted a worse treatment outcome. Source localization of these delta and high beta oscillations corresponded with previous EEG resting-state findings in OCD patients compared to healthy controls. Conclusion: Independent component NFB in OCD proved useful in percentage improvement of compulsions. Based on our correlation analyses, we hypothesize that we targeted a network related to treatment resistance.

Frontoparietal activity during deceptive responses in the P300-based guilty knowledge test: An sLORETA study

The cortical source activity during the P300-based guilty knowledge test (GKT) conducted using Korean sentences was investigated. Thirty male students performed a guilty or an innocent scenario, and then underwent an electroencephalogram test. The stimuli consisted of target, probe, and irrelevant stimuli that were presented visually. A target stimulus is a task-relevant stimulus that is presented rarely, attracts subjects' attention, and induces a P300 wave. A probe stimulus, also presented rarely, contains crime-relevant information that induces P300 in a guilty subject. A guilty subject would be also attentive to the probe stimulus as to the target stimulus. An irrelevant stimulus is not related to the task or to the crime, and is frequently presented. Event-related potential (ERP) data showed a marked difference between the guilty and innocent groups. Compared to irrelevant stimuli, the probe stimulus elicited larger P300 amplitude in the bilateral frontoparietal region in the guilty group. However, this pattern was not observed in the innocent group. Standardized low-resolution electromagnetic tomography (sLORETA) analysis showed significant activation increases for the probe stimulus in the guilty group. It appears that the guilty and innocent groups use different cognitive mechanisms when processing the crime-relevant sentence. With regards to the cortical activity in response to the probe stimulus, the frontal activation for verb elements seems to reflect a working memory process, episodic memory retrieval, and response inhibition, while parietal activation for complement (adverb) and object (noun) elements seems to reflect selective attention and target discrimination. To our knowledge, this is the first research to examine the cortical source of the ERP evoked by the P300-based GKT using separate Korean sentence elements.

Clinical Advantages of Quantitative Electroencephalogram (QEEG)–Electrical Neuroimaging Application in General Neurology Practice

QEEG-electrical neuroimaging has been underutilized in general neurology practice for uncertain reasons. Recent advances in computer technology have made this electrophysiological testing relatively inexpensive. Therefore, this study was conducted to evaluate the clinical usefulness of QEEG/electrical neuroimaging in neurological practice. Over the period of approximately 6 months, 100 consecutive QEEG recordings were analyzed for potential clinical benefits. The patients who completed QEEG were divided into 5 groups based on their initial clinical presentation. The main groups included patients with seizures, headaches, post-concussion syndrome, cognitive problems, and behavioral dysfunctions. Subsequently, cases were reviewed and a decision was made as to whether QEEG analysis contributed to the diagnosis and/or furthered patient's treatment. Selected and representative cases from each group are presented in more detail, including electrical neuroimaging with additional low-resolution electromagnetic tomography analysis or using computerized cognitive testing. Statistical analysis showed that QEEG analysis contributed to 95% of neurological cases, which indicates great potential for wider application of this modality in general neurology. Many patients also began neurotherapy, depending on the patient's desire to be involved in this treatment modality.

Standardized Low Resolution Electromagnetic Tomography (s_LORETA) is a Sensitive Indicator of Protracted Neuropsychological Impairments Following “Mild” (Concussive) Traumatic Brain Injury

Background: Differentiation of patients who have sustained a mild TBI and who show continued difficulties with adaptation is a major clinical challenge and a time-consuming process when classical neuropsychological testing is involved. LORETA (Low Resolution Electromagnetic Tomography) was employed to discern its sensitivity for differentiating the regions of the cerebrum for patients who exhibited continued difficulties with adaptation and showed either no or formal neuropsychological impairment years after the injury. Methods: The quantitative electroencephalographic data for total of 14 patients who had sustained a mild TBI and who either displayed moderately-severe neuropsychological impairment (n=7) or did not (n=7) according to the results of a standardized battery were analyzed by s_LORETA software. The centroid Talairach (X,Y,Z) components for each major frequency band that were significantly different between the two populations were computed. Results: Averaged s_LORETAs demonstrated that the group of patients who displayed formal moderate-severe neuropsychological impairments more than five years after the injury displayed differential power values compared to the group of patients who also sustained a TBI but exhibited no formal impairment within regions that were consistent with the residual subjective symptoms. The s_LORETA analyses, including data collection, required less than 1 hr. Conclusion: A 30 minute sample of QEEG data when applied to s_LORETA software can reveal the general regions of the cerebrum that remain anomalous for years after the initial injury. Employment of this technology could be more efficient and provide greater precision for the strategic interventions that could facilitate the patients’ adaptation.

Cocaine Dependent Individuals and Gamblers Present Different Associative Learning Anomalies in Feedback-Driven Decision Making: A Behavioral and ERP Study.

Several recent studies have demonstrated that addicts behave less flexibly than healthy controls in the probabilistic reversal learning task (PRLT), in which participants must gradually learn to choose between a probably rewarded option and an improbably rewarded one, on the basis of corrective feedback, and in which preferences must adjust to abrupt reward contingency changes (reversals). In the present study, pathological gamblers (PG) and cocaine dependent individuals (CDI) showed different learning curves in the PRLT. PG also showed a reduced electroencephalographic response to feedback (Feedback-Related Negativity, FRN) when compared to controls. CDI’s FRN was not significantly different either from PG or from healthy controls. Additionally, according to Standardized Low-Resolution Electromagnetic Tomography analysis, cortical activity in regions of interest (previously selected by virtue of their involvement in FRN generation in controls) strongly differed between CDI and PG. However, the nature of such anomalies varied within-groups across individuals. Cocaine use severity had a strong deleterious impact on the learning asymptote, whereas gambling intensity significantly increased reversal cost. These two effects have remained confounded in most previous studies, which can be hiding important associative learning differences between different populations of addicts.

Neural substrates of normal and impaired preattentive sensory discrimination in large cohorts of nonpsychiatric subjects and schizophrenia patients as indexed by MMN and P3a change detection responses

Schizophrenia (SZ) patients have information processing deficits, spanning from low level sensory processing to higher-order cognitive functions. Mismatch negativity (MMN) and P3a are event-related potential (ERP) components that are automatically elicited in response to unattended changes in ongoing, repetitive stimuli that provide a window into abnormal information processing in SZ. MMN and P3a are among the most robust and consistently identified deficits in SZ, yet the neural substrates of these responses and their associated deficits in SZ are not fully understood. This study examined the neural sources of MMN and P3a components in a large cohort of SZ and nonpsychiatric control subjects (NCS) using Exact Low Resolution Electromagnetic Tomography Analyses (eLORETA) in order to identify the neural sources of MMN and P3a as well as the brain regions associated with deficits commonly observed among SZ patients. 410 SZ and 247 NCS underwent EEG testing using a duration-deviant auditory oddball paradigm (1-kHz tones, 500ms SOA; standard p=0.90, 50-ms duration; deviant tones P=0.10, 100-ms duration) while passively watching a silent video. Voxel-by-voxel within- (MMN vs. P3a) and between-group (SZ vs. NCS) comparisons were performed using eLORETA. SZ had robust deficits in MMN and P3a responses measured at scalp electrodes consistent with other studies. These components mapped onto neural sources broadly distributed across temporal, frontal, and parietal regions. MMN deficits in SZ were associated with reduced activations in discrete medial frontal brain regions, including the anterior-posterior cingulate and medial frontal gyri. These early sensory discriminatory MMN impairments were followed by P3a deficits associated with widespread reductions in the activation of attentional networks (frontal, temporal, parietal regions), reflecting impaired orienting or shifts of attention to the infrequent stimuli. MMN and P3a are dissociable responses associated with broadly distributed patterns of neural activation. MMN deficits among SZ patients appear to be primarily accounted for by reductions in medial prefrontal brain regions that are followed by widespread dysfunction across cortical networks associated with P3a in a manner that is consistent with hierarchical information processing models of cognitive deficits in SZ patients. Impairments in automatic stimulus discrimination may contribute to higher-order cognitive and psychosocial deficits in SZ.

Application of Quantitative Electroencephalography (QEEG) and Low Resolution Electro-Magnetic Tomography Analysis (LORETA) in General Neurology Practice for Detection and Localization of Epilepsy (P01.050)

Objective: To evaluate clinical usefulness of QEEG and LORETA in diagnosis and localization of epilepsy in general neurology settings. Background Standard digital EEG is frequently not diagnostic in detection of epilepsy. EEG-telemetry is superior to standard digital EEG in confirmation of epilepsy diagnosis, however requires patient hospitalization and is relatively expensive. QEEG and LORETA have been underutilized in general neurology practice for uncertain reasons. Due to remarkable advancement in computer technology and low cost of computers, QEEG technology became affordable for any medical practice. Therefore, this study was conducted in order to evaluate the clinical usefulness of QEEG and LORETA for diagnosis and localization of epilepsy in general neurological practice. Design/Methods: This is multiple case study from single general neurology practice. Over the period of approximately 8 months, 16 consecutive patients suspected of having epilepsy were analyzed using QEEG and/or LORETA for potential clinical benefits including diagnosis confirmation or better localization of cortical dysfunction. Prior work up included MRI of the brain and standard digital EEG-frequently read as normal. Results: Out of 16 patients 4 (25%) patients who had normal standard digital EEG were found to have localized functional abnormality on QEEG and/or LORETA testing. Subsequently EEG-telemetry which was completed in 3 of those 4 patients detected seizures coming from these QEEG identified dysfunctional regions. 3 additional patients have had both abnormal standard digital EEG and QEEG. Additional group of patients had positive QEEG findings which were not fully conclusive due to coexistent neurodegenerative or neurodevelopmental disease. Conclusions: These findings indicate a clinical usefulness of EEG/LORETA in general neurology practice for diagnosing and localization of epilepsy. Disclosure: Dr. Koberda has nothing to disclose.

Brain Oscillatory Activity during Spatial Navigation: Theta and Gamma Activity Link Medial Temporal and Parietal Regions

Brain oscillatory correlates of spatial navigation were investigated using blind source separation (BSS) and standardized low resolution electromagnetic tomography (sLORETA) analyses of 62-channel EEG recordings. Twenty-five participants were instructed to navigate to distinct landmark buildings in a previously learned virtual reality town environment. Data from periods of navigation between landmarks were subject to BSS analyses to obtain source components. Two of these cortical sources were found to exhibit significant spectral power differences during navigation with respect to a resting eyes open condition and were subject to source localization using sLORETA. These two sources were localized as a right parietal component with gamma activation and a right medial-temporal-parietal component with activation in theta and gamma bandwidths. The parietal gamma activity was thought to reflect visuospatial processing associated with the task. The medial-temporal-parietal activity was thought to be more specific to the navigational processing, representing the integration of ego- and allo-centric representations of space required for successful navigation, suggesting theta and gamma oscillations may have a role in integrating information from parietal and medial-temporal regions. Theta activity on this medial-temporal-parietal source was positively correlated with more efficient navigation performance. Results are discussed in light of the depth and proposed closed field structure of the hippocampus and potential implications for scalp EEG data. The findings of the present study suggest that appropriate BSS methods are ideally suited to minimizing the effects of volume conduction in noninvasive recordings, allowing more accurate exploration of deep brain processes.

N300 indexes deficient integration of orthographic and phonological representations in children with dyslexia

In transparent orthographies, like German, children with developmental dyslexia (DD) are mainly characterized by a reading fluency deficit. The reading fluency deficit might be traced back to a scarce integration of orthographic and phonological representations. In order to address this question, the present study used EEG to investigate the N300, an ERP component which has been associated with the integration of orthographic and phonological representations. Twenty children without DD and 18 children with DD performed a phonological (P)–orthographic (O) matching task (P–O condition), which tapped the integration of orthographic and phonological representations. A control task was applied which did not require the integration of orthographic and phonological representations and consisted only of orthographic information (O–O condition). The O–O condition revealed a similar N300 distribution between groups with a bilateral activity over fronto-temporal electrodes. However, in the P–O condition N300 differentiated the 2 groups of children. The control group revealed greater activity over left fronto-temporal electrodes, whereas the N300 was distributed bilaterally in the group of children with DD suggesting deficient integration of orthographic and phonological representations. These findings might be related to the reading fluency deficit as it was also observed that better reading fluency was correlated with higher (r=−.36) and earlier peaking (r=−.33) N300 amplitudes in the left hemisphere and attenuated N300 amplitudes (r=.45) in the right hemisphere. Standardized low-resolution electromagnetic tomography analysis (sLORETA) revealed that children with DD rely more on right temporo-parietal brain areas compared to children without DD. Furthermore, in order to rule out that earlier deficient processes might influence the group differences found in the N300, we analyzed the N170 for group differences. We did not find significant differences between children without DD and children with DD. In conclusion the results suggest deficient integration of orthographic and phonological representations in dyslexia, as indexed by the N300, and further highlight how this activity is relevant for fluent reading.

Neurocognitive deficits in male alcoholics: An ERP/sLORETA analysis of the N2 component in an equal probability Go/NoGo task

In alcoholism research, studies concerning time-locked electrophysiological aspects of response inhibition have concentrated mainly on the P3 component of the event-related potential (ERP). The objective of the present study was to investigate the N2 component of the ERP to elucidate possible brain dysfunction related to the motor response and its inhibition using a Go/NoGo task in alcoholics. The sample consisted of 78 abstinent alcoholic males and 58 healthy male controls. The N2 peak was compared across group and task conditions. Alcoholics showed significantly reduced N2 peak amplitudes compared to normal controls for Go as well as NoGo task conditions. Control subjects showed significantly larger NoGo than Go N2 amplitudes at frontal regions, whereas alcoholics did not show any differences between task conditions at frontal regions. Standardized low resolution electromagnetic tomography analysis (sLORETA) indicated that alcoholics had significantly lower current density at the source than control subjects for the NoGo condition at bilateral anterior prefrontal regions, whereas the differences between groups during the Go trials were not statistically significant. Furthermore, NoGo current density across both groups revealed significantly more activation in bilateral anterior cingulate cortical (ACC) areas, with the maximum activation in the right cingulate regions. However, the magnitude of this difference was much less in alcoholics compared to control subjects. These findings suggest that alcoholics may have deficits in effortful processing during the motor response and its inhibition, suggestive of possible frontal lobe dysfunction.

EEG source analysis in obsessive–compulsive disorder

Objective The goal of this study was to assess the activity of intracortical EEG sources in patients with OCD. Methods We compared resting state EEG from 50 OCD patients and 50 matched controls using standardized low-resolution electromagnetic tomography (sLORETA) and normative independent component analysis (NICA). Data were analyzed with 1 Hz frequency resolution. Group ICA was used to separate seven independent components from the control group data. The resulting weights and norms served to derive the same components from the OCD group and to compare their power with controls. Results In OCD, sLORETA indicated low-frequency power excess (2–6 Hz) in the medial frontal cortex, whereas group ICA showed increased low-frequency power in a component reflecting the activity of subgenual anterior cingulate, adjacent limbic structures and to a lesser extent also of lateral frontal cortex. Conclusions Both methods provided evidence for medial frontal hyperactivation in OCD. Significance Our study is the first to use normative ICA in a clinical sample and indicates its potential utility as a diagnostic tool. The findings provide consistent results based on EEG source localization in OCD and are of practical interest for therapeutic interventions.

Quantitative EEG abnormalities in persons with “pure” epileptic predisposition without epilepsy: A low resolution electromagnetic tomography (LORETA) study

Epileptic predisposition means genetically determined, increased seizure susceptibility. Neurophysiological evaluation of this condition is still lacking. In order to investigate "pure epileptic predisposition" (without epilepsy) in this pilot study the authors prospectively recruited ten persons who displayed generalized tonic-clonic seizures precipitated by 24 or more hours of sleep deprivation but were healthy in any other respects. 21-channel EEGs were recorded in the morning, in the waking state, after a night of sufficient sleep in the interictal period. For each person, a total of 120s artifact-free EEG was processed to low resolution electromagnetic tomography (LORETA) analysis. LORETA activity (Ampers/meters squared) was computed for 2394 voxels, 19 active electrodes and 1Hz very narrow bands from 1 to 25Hz. The data were compressed into four frequency bands (delta: 0.5-4.0Hz, theta: 4.5-8.0Hz, alpha: 8.5-12.0Hz, beta: 12.5-25.0Hz) and projected onto the MRI figures of a digitized standard brain atlas. The band-related LORETA results were compared to those of ten, age- and sex-matched healthy persons using independent t-tests. p<0.01 differences were accepted as statistically significant. Statistically significant decrease of alpha activity was found in widespread, medial and lateral parts of the cortex above the level of the basal ganglia. Maximum alpha decrease and statistically significant beta decrease were found in the left precuneus. Statistically not significant differences were delta increase in the medial-basal frontal area and theta increase in the same area and in the basal temporal area. The significance of alpha decrease in the patient group remains enigmatic. beta decrease presumably reflects non-specific dysfunction of the cortex. Prefrontal delta and theta increase might have biological meaning despite the lack of statistical significance: these findings are topographically similar to those reported in idiopathic generalized epilepsy in previous investigations. Quantitative EEG characteristics of the genetically determined epilepsy predisposition were given in terms of frequency bands and anatomical distribution.

Effect of initiation-inhibition and handedness on the patterns of the P50 event-related potential component: a low resolution electromagnetic tomography study.

BackgroundRecent research recognizes the association between handedness, linguistic processes and cerebral networks subserving executive functioning, but the nature of this association remains unclear. Since the P50 event related potential (ERP) is considered to reflect thalamocortical processes in association with working memory (WM) operation the present study focuses on P50 patterns elicited during the performance of a linguistic related executive functioning test in right- and left-handers.MethodsIn 64 young adults with a high educational level (33 left-handed) the P50 event-related potential was recorded while performing the initiation and inhibition condition of a modified version of the Hayling Sentence Completion test adjusted to induce WM. The manual preference of the participants was evaluated with the use of the Edinburgh Handedness Inventory (EHI).ResultsP50 showed greater amplitudes in left- than in right-handers, mainly in frontal leads, in the initiation condition. Reduced amplitudes in inhibition compared to initiation condition were observed in left-handers. Low Resolution Electromagnetic Tomography (LORETA) analysis showed lower frontal lobe activation in the inhibition than in the initiation condition in both right- and left-handers. Also, LORETA yielded that right-handers exhibited greater activation in the inhibition condition than left-handers. Additionally, LORETA showed assymetrical hemispheric activation patterns in right-handers, in contrast to symmetrical patterns observed in left-handers. Higher P50 amplitudes were recorded in right-hemisphere of right-handers in the initiation condition.ConclusionBrain activation, especially the one closely related to thalamocortical function, elicited during WM operation involving initiation and inhibition processes appears to be related to handedness.

Low resolution electromagnetic tomography analysis of ictal EEG patterns in mesial temporal lobe epilepsy with hippocampal sclerosis

To investigate the difference in the spatial distribution of scalp initial ictal discharge (IID) patterns in mesial temporal lobe epilepsy with hippocampal sclerosis (HS-MTLE). Scalp ictal EEG data in 22 seizure-free patients after temporal lobectomy with amygdalo-hippocampectomy were classified as follows: a regular 5-9Hz rhythm with a restricted temporal/subtemporal distribution (type 1, 11 patients), or an irregular 2-5Hz rhythm with a widespread fronto-temporal distribution (type 2, 11 patients). EEG data were fragmented into segments of 1.28s, both at ictal onset and at baseline. The LORETA solution of three frequency bands was compared between ictal and baseline using statistical non-parametric mapping (p<0.01). The LORETA solution of 5-9Hz in type 2 had wider cortical activity in the ipsilateral fronto-temporal area, compared to type 1 with activation of the ipsilateral focal mesial and lateral temporal regions. The LORETA solution of 10-13Hz in both types showed increased activity in the fronto-temporal area, which was wider in type 2 than type 1. Increased cortical activity of <5Hz was not observed in type 1, whereas increased cortical activity was observed in the bilateral anterior frontal area in type 2. The cortical source distribution in HS-MTLE may depend on scalp IID frequency. The neural generators of 5-13Hz may be important for the formation of the ictal onset zone in both ictal patterns. Spatial distributions in HS-MTLE patients differ with scalp IID frequency.

Functional Neuroanatomy and the Rationale for Using EEG Biofeedback for Clients with Asperger’s Syndrome

This paper reviews the symptoms of Asperger's Syndrome (AS), a disorder along the autism continuum, and highlights research findings with an emphasis on brain differences. Existing theories concerning AS are described, including theory of mind (Hill and Frith in Phil Trans Royal Soc Lond, Bull 358:281-289, 2003), mirror neuron system (Ramachandran and Oberman in Sci Am 295(5):62-69, 2006), and Porges' (Ann N Y Acad Sci 1008:31-47, 2003, The neurobiology of autism, Johns Hopkins University Press, Baltimore, 2004) polyvagal theory. (A second paper, Outcomes using EEG Biofeedback Training in Clients with Asperger's Syndrome, summarizes clinical outcomes obtained with more than 150 clients.) Patterns seen with QEEG assessment are then presented. Single channel assessment at the vertex (CZ) reveals patterns similar to those found in Attention-Deficit/Hyperactivity Disorder. Using 19-channel data, significant differences (z-scores > 2) were found in the amplitude of both slow waves (excess theta and/or alpha) and fast waves (beta) at various locations. Differences from the norm were most often found in mirror neuron areas (frontal, temporal and temporal-parietal). There were also differences in coherence patterns, as compared to a normative database (Neuroguide). Low Resolution Electromagnetic Tomography Analysis (Pascual-Marqui et al. in Methods Find Exp Clin Pharmacol 24C:91-95, 2002) suggested the source of the abnormal activity was most often the anterior cingulate. Other areas involved included the amygdala, uncus, insula, hippocampal gyrus, parahippocampal gyrus, fusiform gyrus, and the orbito-frontal and/or ventromedial areas of the prefrontal cortex. Correspondence between symptoms and the functions of the areas found to have abnormalities is evident and those observations are used to develop a rationale for using EEG biofeedback, called neurofeedback (NFB), intervention. NFB training is targeted to improve symptoms that include difficulty reading and mirroring emotions, poor attention to the outside world, poor self-regulation skills, and anxiety. Porges' polyvagal theory is used to emphasize the need to integrate NFB with biofeedback (BFB), particularly heart rate variability training. We term this emerging understanding the Systems Theory of Neural Synergy. The name underscores the fact that NFB and BFB influence dynamic circuits and emphasizes that, no matter where we enter the nervous system with an intervention, it will seek its own new balance and equilibrium.