bluuebunny/crossref_metadata_2025 huggingface dataset:
nCPAP Treatment of Obstructive Sleep Apnea Increases Slow Wave Sleep in Prefrontal EEG
Authors: Eskelinen Veera , Uibu Toomas , Himanen Sari-Leena
Published: February 2012

According to standard sleep stage scoring, sleep EEG is studied from the central area of parietal lobes. However, slow wave sleep (SWS) has been found to be more powerful in frontal areas in healthy subjects. Obstructive sleep apnea syndrome (OSAS) patients often suffer from functional disturbances in prefrontal lobes.

We studied the effects of nasal Continuous Positive Airway Pressure (nCPAP) treatment on sleep EEG, and especially on SWS, in left prefrontal and central locations in 12 mild to moderate OSAS patients. Sleep EEG was recorded by polysomnography before treatment and after a 3 month nCPAP treatment period. Recordings were classified into sleep stages. No difference was found in SWS by central sleep stage scoring after the nCPAP treatment period, but in the prefrontal lobe all night S3 sleep stage increased during treatment. Furthermore, prefrontal SWS increased in the second and decreased in the fourth NREM period. There was more SWS in prefrontal areas both before and after nCPAP treatment, and SWS increased significantly more in prefrontal than central areas during treatment. Regarding only central sleep stage scoring, nCPAP treatment did not increase SWS significantly. Frontopolar recording of sleep EEG is useful in addition to central recordings in order to better evaluate the results of nCPAP treatment.
Complex Partial Status Epilepticus in Paraneoplastic Limbic Encephalitis
Authors: Kile S. J. , Kim J. C. , Seyal M.
Published: February 2012

Paraneoplastic limbic encephalitis (PLE) results from tumor-related autoimmune mediated inflammation and degeneration of the mesial temporal structures. Cognitive and behavioral changes and seizures occur in PLE. Seizures are an uncommon presenting symptom of PLE occurring in 6 of 50 patients in one series. We present a report of complex partial status epilepticus (CPSE) as the presentation of PLE with anti-neuronal antibodies and improvement in mental status following treatment of seizures.
Event-Related Desynchronization of Frontal-Midline Theta Rhythm during Preconscious Auditory Oddball Processing
Authors: Kawamata Masaru , Kirino Eiji , Inoue Reiichi , Arai Heii
Published: February 2012

The goal of this study was to explore the frontal-mid-line theta rhythm (Fm theta) generation mechanism employing event-related desynchronization/synchronization (ERD/ERS) analysis in relation to task-irrelevant external stimuli. A dual paradigm was employed: a videogame and the simultaneous presentation of passive auditory oddball stimuli. We analyzed the data concerning ERD/ERS using both Fast Fourier Transformation (FFT) and wavelet transform (WT).

In the FFT data, during the periods with appearance of Fm theta, apparent ERD of the theta band was observed at Fz and Cz. ERD when Fm theta was present was much more prominent than when Fm theta was absent. In the WT data, as in the FFT data, ERD was seen again, but in this case the ERD was preceded by ERS during both the periods with and without Fm theta. Furthermore, the WT analysis indicated that ERD was followed by ERS during the periods without Fm theta. However, during Fm theta, no apparent ERS following ERD was seen.

In our study, Fm theta was desynchronized by the auditory stimuli that were independent of the video game task used to evoke the Fm theta. The ERD of Fm theta might be reflecting the mechanism of “positive suppression” to process external auditory stimuli automatically and preventing attentional resources from being unnecessarily allocated to those stimuli. Another possibility is that Fm theta induced by our dual paradigm may reflect information processing modeled by multi-item working memory requirements for playing the videogame and the simultaneous auditory processing using a memory trace. ERS in the WT data without Fm theta might indicate further processing of the auditory information free from “positive suppression” control reflected by Fm theta.
EEG Coherence for a Patient with Marchiafava-Bignami Disease
Authors: Fang Shih-Chin , Hsu Jung-Lung , Chen Wei-Hung
Published: February 2012

We evaluated a 39-year-old chronic alcoholic man with acute multiple cognitive impairment and callosal lesion seen in MRI, diagnosed as Marchiafava-Bignami disease (MBD), using analysis of electroencephalography (EEG) coherence. Three EEG sessions were recorded in the first week, the second and eighth month after disease onset in the MBD patient. Inter-hemispheric coherence (IhC), parasagittal coherence (PsC) and spatially averaged coherence (SAC) were computed. The results were compared with normative data from 30 age-matched healthy subjects.

Mean values for IhC, PsC and SAC were significantly decreased during the acute stage of the disease (P<0.01). The IhC values remained low (P<0.01), however, PsC and SAC values rebounded in follow-up study. The IhC and SAC values were lowest in the frontal region, consistent with the main pathological involvement in the anterior two-thirds of the corpus callosum and early involvement of frontal cortex.

In conclusion, MBD may manifest as a cerebral-disconnection state, which can be quantified using EEG-coherence analysis. EEG-coherence may serve as a useful tool for MBD diagnosis and evaluation.
Midline Spikes
Authors: Yong T. , Chayasirisobhon S. , Yoshina J. S. , Tin S. N. , Tehrani K. , Skinner S. E. , Markus E. , Spurgeon B. D. , Gurbani S.
Published: February 2012

Midline spikes are characterized by spike foci recorded at Cz, Fz, or Pz with amplitude ranging from 20 to 350 microvolts. Out of 7,929 EEGs performed at the Neurodiagnostics Laboratory, Kaiser Permanente Medical Center, Anaheim, California, between 1996 and 2006, 17 EEGs (0.21%) were identified as having interictal midline spikes with or without other epileptiform discharges. Eight EEGs showed midline spikes at Cz, 2 at Fz, 2 at Cz and Fz, 1 at Cz and C3, 1 at Cz, C3, and P3, 1 at Cz and F8, 1 at Cz and T4, and 1 at Cz with 2 Hz generalized spike and slow wave complex. Midline spikes were recorded in 10 males and 7 females. The age ranged from 4 days to 38-years-old with a mean age of 10.8 years. Twelve patients (70.6%) were children. Twelve patients (70.6%) had generalized tonic-clonic seizures and 5 had partial motor seizures. Of the 17 patients, 14 had no known causes, 1 had an agenesis of corpus callosum, 1 had a left frontal arteriovenous malformation, and 1 had a left frontal area stroke.

We postulate that the mechanism for the genesis of midline spikes may be heterogeneous. Midline spikes may be triggered by thalamocortical network in a generalized tonic-clonic seizure, or may originate in the parasagittal cortex in a partial motor seizure.
Focal EEG Findings in Juvenile Absence Syndrome and the Effect of Antiepileptic Drugs
Authors: Tezer F. Irsel , Sahin Gurdal , Ciger Abdurrahman , Saygi Serap
Published: February 2012

The presence of focal EEG abnormalities in juvenile absence syndrome (JAS) may cause it to be misdiagnosed as focal epilepsy. The purpose of our study was to determine the presence of focal EEG abnormalities in patients with JAS and to ascertain whether some clinical features or antiepileptic drugs (AEDs) have an effect on focality.

Serial EEGs of 52 consecutive patients with JAS were retrospectively analyzed. The patients were divided into two groups according to whether they were treated with valproic acid and/or lamotrigine (VA-LTG) or not during the times of these EEG recordings. The relationship between the presence of EEG focality and the use of AEDs in addition to other risk factors was examined.

Two or three consecutive EEGs (total 100) of the 52 patients were evaluated. Among these, the rates of focal EEG abnormalities were 18%, 36%, and 25% during the follow-up EEGs without AEDs (5/27) and first (16/45) and second EEGs (7/28) with AEDs, respectively. The last two EEGs showed a tendency towards a higher proportion of EEG focality in patients who received other AEDs (47%-45%) compared with those that received VA-LTG (13%-12%).

The proportion of JAS patients with focal EEG findings in serial EEGs tended to decrease with an increasing rate of VA-LTG use. As a hypothetical explanation, changes in EEG focality may reflect the effect of AEDs other than VA and/or LTG, in addition to a developing hyperexcitable cortical area.
Simultaneous EEG-fMRI: Perspectives in Psychiatry
Authors: Mulert Christoph , Pogarell Oliver , Hegerl Ulrich
Published: February 2012

Neurophysiological findings such as reduced amplitudes of the P300 potential in patients with schizophrenia are among the most robust findings in biological psychiatry. An enormous literature with findings of abnormal central processing in psychiatric diseases has been acquired during the last decades. However, the benefit of this research has been limited in part due to the unresolved problem of precise and correct localization of the underlying neural generators. The difficulty of correct localization is due to the fact that different constellations of cortical neuroelectric generators can produce identical EEG activity. Therefore, even concerning several major event related potentials no generally accepted knowledge about their cerebral generation exists. While correct localization can easily be obtained by imaging methods based on hemodynamic changes such as functional magnetic resonance imaging (fMRI), these techniques can not distinguish between different aspects of neural activity such as oscillation modes or stages of information processing that are only some milliseconds apart. Accordingly, the integration of simultaneous measurements of EEG and fMRI has become a methodological key issue today. EEG-fMRI may prove to be crucial in providing much deeper understanding of brain activity over the next decades. This review summarizes the basic physiology, methodological issues and interesting applications in psychiatry.
Endophenotypes, Dimensions, Risks: Is Psychosis Analogous to Common Inherited Medical Illnesses?
Authors: Pearlson Godfrey D. , Folley Bradley S.
Published: February 2012

Psychiatric illnesses are perceived as fundamentally different from common medical disorders, a view arising from the mind-body problem and difficulties relating the brain's emergent properties to its physiological substrates. However, schizophrenia and many common medical illnesses are heritable and result from the influence of both genetic and environmental sources. Unlike illnesses such as Huntington's disease, which are caused by a fully penetrant dominant mutation, no single “schizophrenia gene” has been identified. Instead, schizophrenia is likely caused by common variants of many genes, each contributing a subtle effect. Schizophrenia genetically resembles common medical illnesses such as type 2 diabetes, ischemic heart disease, and familial hypercholesterolemia, that have an associated genetic variant, but that are also influenced by other factors such as diet, culture and habits. Just as these illnesses operate through complex gene/environment interaction, schizophrenia is likely caused by several gene variants, neurodevelopmental processes, and learned behavioral response biases. These clinical diseases, however, represent severe forms of the phenotype for both psychiatric and medical illnesses. From a dimensional perspective, individuals possessing the same genotype could express milder forms of the clinical disorder along a spectrum of related traits. We discuss this perspective in the context of an endophenotypic and biological marker approach to understanding schizophrenia and present a research strategy to compare schizophrenia endophenotypes to risk for common medical illnesses.
Auditory/Verbal Hallucinations, Speech Perception Neurocircuitry, and the Social Deafferentation Hypothesis
Authors: Hoffman Ralph E.
Published: February 2012

Auditory/verbal hallucinations (AVHs) are comprised of spoken conversational speech seeming to arise from specific, nonself speakers. One hertz repetitive transcranial magnetic stimulation (rTMS) reduces excitability in the brain region stimulated. Studies utilizing 1-Hz rTMS delivered to the left temporoparietal cortex, a brain area critical to speech perception, have demonstrated statistically significant improvements in AVHs relative to sham simulation. A novel mechanism of AVHs is proposed whereby dramatic pre-psychotic social withdrawal prompts neuroplastic reorganization by the “social brain” to produce spurious social meaning via hallucinations of conversational speech. Preliminary evidence supporting this hypothesis includes a very high rate of social withdrawal emerging prior to the onset of frank psychosis in patients who develop schizophrenia and AVHs. Moreover, reduced AVHs elicited by temporoparietal 1-Hz rTMS are likely to reflect enhanced long-term depression. Some evidence suggests a loss of long-term depression following experimentally-induced deafferentation. Finally, abnormal cortico-cortical coupling is associated with AVHs and also is a common outcome of deafferentation.

Auditory/verbal hallucinations (AVHs) of spoken speech or “voices” are reported by 60–80% of persons with schizophrenia at various times during the course of illness. 1 – 2 AVHs are associated with high levels of distress, 3 – 5 functional disability, 6 and can lead to violent acts. 7 , 8 Among patients with AVHs, these symptoms remain poorly or incompletely responsive to currently available treatments in approximately 25% of cases. 9 For patients with AVHs who do respond to antipsychotic drugs, there is a very high likelihood that these experiences will recur in subsequent episodes. 10 A more precise characterization of underlying pathophysiology may lead to more efficacious treatments.
Hallucinations, Thought Disorders, and the Language Domain in Schizophrenia
Authors: Strik W. , Dierks T. , Hubl D. , Horn H.
Published: February 2012

Auditory hallucinations and formal thought disorders are major diagnostic features of schizophrenia. From a neurobiological point of view, they are of particular interest since both can be attributed to the language domain of human communication. In the last decade, brain imaging studies have contributed to the understanding of the functional dynamics underlying these phenomena. In particular, auditory hallucinations were found to involve the regions generating inner speech as well as the primary acoustical cortex and the intrahemispheric fiber bundles connecting the left frontal with the temporal lobe. In patients with formal thought disorders, on the other hand, the left temporal language area showed structural deficits and functional abnormalities, i.e., reduced reactivity to stimulation and increased activity at rest; left frontal language regions were also hyperactive at rest but showed no structural deficits. The available evidence indicates a dynamic imbalance of the language system, triggered by subtle structural changes, as the possible common neurobiological basis of hallucinations and formal thought disorders.
Semantic Activation and Verbal Working Memory Maintenance in Schizophrenic Thought Disorder: Insights from Electrophysiology and Lexical Amibiguity
Authors: Salisbury Dean F.
Published: February 2012

We have examined language processing using ambiguous words (homographs like panel or toast) and rapid or slow presentation rates while recording event-related brain potentials (ERPs). Homographs allow for tracking the train of thought at points of lexical ambiguity and detecting modulation of associative threads by previous context. Rapid presentation rates stress automatic semantic activation, and slow rates stress controlled verbal working memory contextual modulation. In conjunction with reaction times and performance, ERPs allow for objective measurement of activity related to language processing from word presentation through overt behavioral response. Smaller N400 to related and unrelated items at short stimulus onset asynchronies (SOAs), the presence of a semantic bias, and large N400 to related and unrelated items at long SOAs are present in schizophrenia. We describe a model of initial semantic memory hyper-priming and subsequent decay of information in verbal working memory stores, the activation-maintenance model of schizophrenic thought disorder hypothesized to underlie the thought disorder in schizophrenia.
Attenuated Modulation of the N170 ERP by Facial Expressions in Schizophrenia
Authors: Lynn S. K. , Salisbury D. F.
Published: February 2012

In psychiatrically-well subjects the modulation of event related potentials (ERPs) by emotional facial expressions is found in several ERPs from −100 ms and later. A face-related EPR, the N170, is abnormally reduced in schizophrenia to faces relative to other complex objects and research suggests emotional modulation of N170 may be reduced as well. To further examine facial emotion modulation of N170, subjects detected neutral facial expressions from among five emotional expressions (happy, sad, fearful, angry, and disgusted). Over occipitotemporal sites, psychiatrically-well subjects showed bilateral differences in N170 amplitude among expressions (P=0.014). Schizophrenia subjects failed to show this modulation (P = 0.551). Accuracy on the task did not differ between groups, nor did the pattern of errors. However, in patients, greater positive and negative symptom ratings were associated with increased failure to button press to neutral faces, suggesting misattribution of emotion to neutral expressions in the more ill patients. Because the N170 is largely specific to faces, these results suggest that an impairment specific to the visual processing of facial expressions contributes to the well-known behavioral abnormalities in facial emotion tasks in schizophrenia.
Cortical Inhibition in Motor and Non-Motor Regions: A Combined TMS-EEG Study
Authors: Fitzgerald Paul B. , Daskalakis Zafiris J. , Hoy Kate , Farzan Faranak , Upton Daniel J. , Cooper Nicholas R. , Maller Jerome J.
Published: February 2012

A number of studies using paired pulse transcranial magnetic stimulation (TMS) have demonstrated that cortical inhibition (CI) of the motor cortex can be recorded and also gauged through surface electromyography. However, recording CI from other brain regions that are more directly related with the pathophysiology of some neurologic and psychiatric disorders (e.g., dorsolateral prefrontal cortex (DLPFC) in schizophrenia) was previously fraught with technical difficulties. This study was therefore designed to examine, through a combination of TMS with EEG, whether CI could be measured directly from the motor cortex, DLPFC, and another non-motor region.

To index CI, long interval cortical inhibition (LICI; a TMS paradigm) was used in the motor cortex and DLPFC in 14 healthy subjects, and in the parietal lobe in 5 of those subjects. In the motor cortex, LICI resulted in a significant suppression in mean cortical evoked activity on EEG (37.31 ± 47.51 %). In the DLPFC, LICI resulted in a significant suppression (32.45 ± 47.86 %) in mean cortical evoked activity and did not correlate with LICI in the motor cortex although they did not significantly differ. In the parietal lobe, LICI resulted in significant suppression (47.76 ± 44.70 %) in mean cortical evoked activity.

In conclusion, CI in the dorsolateral prefrontal cortex, motor cortex and parietal cortex were similar at 120% of motor threshold. These data suggest that CI can be recorded by combining TMS with EEG and may facilitate future research attempting to ascertain the role of CI in the pathophysiology of several neurologic and psychiatric disorders.
Effects of rTMS on an Auditory Oddball Task: A Pilot Study of Cortical Plasticity and the EEG
Authors: Cooper N.R. , Fitzgerald P.B. , Croft R.J. , Upton D.J. , Segrave R.A. , Daskalakis Z.J. , Kulkarni J.
Published: February 2012

The objective of this study was to explore the effects of 1Hz repetitive transcranial magnetic stimulation (rTMS) applied to dorsal lateral prefrontal cortex (DLPFC) on both an EEG index of cortical excitation and inhibition, event-related desynchronization/synchronization (ERD/S) and on the P300 component of an auditory oddball-induced ERP. Eight normal participants received 15 minutes of 1Hz rTMS at 110% of the resting motor threshold to right DLPFC. ERD/S of alpha and beta bands was measured during an auditory oddball task immediately before and after stimulation.

There was significantly less alpha desynchronization post-TMS, and this effect was widespread excepting posterior midline sites. No changes were found to oddball-P300 amplitudes or latencies. In conclusion, the findings of less alpha desynchronization post-TMS are compatible with notions of slow rTMS causing a decrease in cortical excitation.
Power Spectral Frequency and Coherence Abnormalities in Patients with Intractable Epilepsy and Their Usefulness in Long-Term Remediation of Seizures Using Neurofeedback
Authors: Walker Jonathan E.
Published: February 2012

Medically intractable seizures appear to be highly correlated with focal slow activity (delta or theta). They also correlate highly with decreases in the coherence of theta. Normalization of focal slowing and of decreased theta coherence will probably be the neurofeedback approaches most likely to decrease or eliminate seizures in future cases.

Neurofeedback has been used for over 35 years to reduce the incidence and severity of seizures. With power training to decrease theta and increase the sensorimotor rhythm (12–15 Hz), an average of 82% of patients experienced a significant reduction in seizure frequency, and occasional remissions were seen. Recent improvements using QEEG to guide neurofeedback training have made it possible to eliminate seizures in most patients, even those with intractable seizures.

Following our previous study in 2005, we report an additional 25 patients so treated. We also report an analysis of the frequency of QEEG abnormalities in this patient group. All of the intractable epileptic patients had one or more slow foci (excessive theta or delta compared with the normal database). One third had a relative deficiency of beta power. One fourth had a deficiency of absolute delta. Eighteen percent had excessive absolute alpha power, 18% had deficient absolute alpha power, 18% percent had excessive absolute beta power, and 18% percent had deficient absolute beta power. Hypocoherence of theta was found in 75%, and decreases in alpha coherence were noted in 42%. Hypocoherence of beta was found in 50%, and hypocoherence of delta was found in 25%. Increases in alpha coherence were noted in 33%. Seventeen percent had no coherence abnormalities.

When most of the power and coherence abnormalities were normalized with neurofeedback training, all the patients became seizure-free; 76% no longer required an anticonvulsant for seizure control.
Cardiopulmonary Resuscitation Artifact during Electroencephalography
Authors: Sethi N. K. , Torgovnick J. , Sethi P. K. , Arsura E.
Published: February 2012

Artifacts are signals recorded on the electroencephalogram (EEG) that are not cerebral in origin and can be divided into physiological and non-physiological artifacts. We present here an interesting non-physiological EEG artifact generated by cardiopulmonary resuscitation efforts.
Evidence-Based Medicine and Neurophysiology
Authors: Geddes John R. , Carney Stuart
Published: February 2012

Evidence-based medicine (EBM) was introduced to meet the increasing need of clinicians to keep up-to-date with the research evidence. EBM integrates advances in information technology with those in clinical epidemiology (the study of the distribution and determinants of disease) to provide a coherent strategy for the timely acquisition of the best available evidence on which to base clinical practice. A fundamental component of EBM has been the development of the methodology of research synthesis. Although the main driver of the development of EBM has been to get existing research into practice, the same approach can be used to inform the development of treatments.
Evidence-Based Medicine Evaluation of Electrophysiological Studies of the Anxiety Disorders
Authors: Clark C. Richard , Galletly Cherrie A. , Ash David J. , Moores Kathryn A. , Penrose Rebecca A. , McFarlane Alexander C.
Published: February 2012

We provide a systematic, evidence-based medicine (EBM) review of the field of electrophysiology in the anxiety disorders. Presently, electrophysiological studies of anxiety focus primarily on etiological aspects of brain dysfunction. The review highlights many functional similarities across studies, but also identifies patterns that clearly differentiate disorder classifications. Such measures offer clinical utility as reliable and objective indicators of brain dysfunction in individuals and indicate potential as biomarkers for the improvement of diagnostic specificity and for informing treatment decisions and prognostic assessments. Common to most of the anxiety disorders is basal instability in cortical arousal, as reflected in measures of quantitative electroencephalography (qEEG). Resting electroencephalographic (EEG) measures tend to correlate with symptom sub-patterns and be exacerbated by condition-specific stimulation. Also common to most of the anxiety disorders are condition-specific difficulties with sensory gating and the allocation and deployment of attention. These are clearly evident from evoked potential (EP) and event-related potential (ERP) electrical measures of information processing in obsessive compulsive disorder (OCD), post-traumatic stress disorder (PTSD), panic disorder (PD), generalized anxiety disorder (GAD) and the phobias. Other ERP measures clearly differentiate the disorders. However, there is considerable variation across studies, with inclusion and exclusion criteria, medication status and control group selection not standardized within condition or across studies. Study numbers generally preclude analysis for confound removal or for the derivation of diagnostic biomarker patterns at this time. The current trend towards development of databases of brain and cognitive function is likely to obviate these difficulties. In particular, electrophysiological measures of function are likely to play a significant role in the development and subsequent adaptations of DSM-V and assist critically in securing improvements in nosological and treatment specificity.
Evidence, Evidence-Based Medicine, and Evidence Utility in Psychiatry and Electrophysiology
Authors: Buchsbaum Monte S.
Published: February 2012

In this issue a series of outstanding and comprehensive reviews of the progress of electrophysiological biomarkers or endophenotype indicators in psychiatric illnesses is presented. These reviews establish presence of electrophysiological abnormalities in symptom-based diagnoses of schizophrenia, dementia, anxiety disorders, substance abuse, and childhood disorders. Diagnostic sensitivity and specificity remain modest in most studies as may be expected for the relationship of indicators of underlying dimensions of brain organization and function when compared by interview-obtained symptom assessment. The power of electrophysiology to mirror pharmacological effects and treatment susceptability is an important resarch direction for electrophysiology.
Source Analysis of Alpha Rhythm Reactivity Using LORETA Imaging with 64-Channel EEG and Individual MRI
Authors: Cuspineda E.R. , Machado C. , Virues T. , Martínez-Montes E. , Ojeda A. , Valdés P. A. , Bosch J. , Valdes L.
Published: February 2012

Conventional EEG and quantitative EEG visual stimuli (close-open eyes) reactivity analysis have shown their usefulness in clinical practice; however studies at the level of EEG generators are limited. The focus of the study was visual reactivity of cortical resources in healthy subjects and in a stroke patient.

The 64 channel EEG and T1 magnetic resonance imaging (MRI) studies were obtained from 32 healthy subjects and a middle cerebral artery stroke patient. Low Resolution Electromagnetic Tomography (LORETA) was used to estimate EEG sources for both close eyes (CE) vs. open eyes (OE) conditions using individual MRI. The t-test was performed between source spectra of the two conditions. Thresholds for statistically significant t values were estimated by the local false discovery rate (lfdr) method. The Z transform was used to quantify the differences in cortical reactivity between the patient and healthy subjects.

Closed-open eyes alpha reactivity sources were found mainly in posterior regions (occipito-parietal zones), extended in some cases to anterior and thalamic regions. Significant cortical reactivity sources were found in frequencies different from alpha (lower t-values). Significant changes at EEG reactivity sources were evident in the damaged brain hemisphere. Reactivity changes were also found in the “healthy” hemisphere when compared with the normal population.

In conclusion, our study of brain sources of EEG alpha reactivity provides information that is not evident in the usual topographic analysis.
PLEDs following Control of Seizures and at the End of Life
Authors: Fishman Olga , Legatt Alan D.
Published: February 2012

Periodic lateralized epileptiform discharges (PLEDs), an EEG pattern that is highly correlated with seizures, may represent an ictal pattern in some patients, but in other patients PLEDs persist despite the absence of seizures or after seizures have been controlled by antiepileptic drugs. The tenacity of PLEDs was illustrated by continuous EEG recording in a 95-year-old woman with multiple old cerebral infarctions who had been admitted to the hospital because of seizures. The EEG showed PLEDs that were maximal in the left central region. These sometimes evolved into EEG seizure patterns, which were correlated with facial twitching. The seizures were controlled by antiepileptic drugs (AEDs), but the PLEDs continued. The patient subsequently expired, with EEG monitoring still in progress. The PLEDs persisted as the patient developed agonal respirations. The interval between the epileptiform complexes gradually increased, and they stopped 40 seconds before disappearance of the other EEG background rhythms; cardiac arrest ensued less than 1 minute later. The resistance of the PLEDs to hypoxia reflects the robustness of the mechanisms that produced them, which may also account for their persistence in the face of AED treatment that stopped the seizures.
Magnetic Resonance Spectroscopy Findings in Photosensitive Idiopathic Generalized Epilepsy
Authors: Aydin-Ozemir Zeynep , Terzibasioglu Ege , Altindag Ebru , Sencer Serra , Baykan Betul
Published: February 2012

Studies investigating the pathophysiology of epileptic photosensitivity indicate variable involvement of particular brain regions. Our aim was to identify metabolic differences between photosensitive idiopathic generalized epilepsy (IGE) patients and nonphotosensitive IGE patients and normal healthy subjects by using Magnetic Resonance Spectroscopy (MRS).

Fourteen patients diagnosed with photosensitive IGE were investigated. The control groups consisted of 14 age- and sex-matched healthy volunteers and 14 IGE patients without photosensitivity. MRS measurements of N-acetylaspartate (NAA), choline-containing compounds (Cho), creatine (Cr) were performed in the frontal and occipital cortex and the thalamus bilaterally using a stimulated echo acquisition mode (STEAM) technique with a voxel size of 20times20times20 mm. The values of the patients with IGE were compared with those of the normal controls and within subgroups according to the clinical variables by appropriate statistical tests.

Photosensitive IGE patients showed significantly decreased concentrations of NAA in the right frontal lobe and left thalamus, decreased NAA/Cr ratio in left thalamus and significantly increased concentrations of Cho/Cr ratio in the right frontal lobe and NAA/Cr in the left occipital lobe when compared to normal controls. Furthermore, left occipital NAA concentration increased and left thalamus NAA/Cr ratios were decreased from the IGE patients without photosensitivity but without reaching statistical significance.

Our results support previous MR studies suggesting an asymmetrical neuronal dysfunction in favor of the dominant occipital cortex and thalamus in photosensitive IGE patients.
The Contribution of Neuroimaging for the Study of Cognitive Deficits in Parkinson's Disease
Authors: Monchi Oury , Martinu Kristina , Strafella Antonio P.
Published: February 2012

The last few years have seen an increase in the number of studies using functional Magnetic Resonance Imaging (fMRI) along with receptor imaging and regional cerebral blood flow Positron Emission Tomography (PET) to understand the neurobiological underpinnings of cognitive deficits in Parkinson's disease (PD). These studies have shown evidence that the nigrostriatal degeneration solely cannot account for these deficits and that involvement of other neural systems such as the mesocortical dopamine may also play an important role. In this article, we provide a review of neuroimaging results regarding the role of possible compensatory activity, L-Dopa medication, and difference in genotypes on the cognitive deficits observed in PD. Finally, some future avenues for research are proposed.
Deep Brain Stimulation of Pedunculopontine Tegmental Nucleus (PPTg) Promotes Cognitive and Metabolic Changes: A Target-Specific Effect or Response to a Low-Frequency Pattern of Stimulation?
Authors: Stefani A. , Pierantozzi M. , Ceravolo R. , Brusa L. , Galati S. , Stanzione P.
Published: February 2012

Deep brain stimulation (DBS) is a reliable treatment for advanced Parkinson's disease (PD) patients, but a possible risk of worsening cognitive functions, although modest, may postpone or halt DBS clinical indication. In a small cohort of PD patients we have pioneered the simultaneous implantation of both the subthalamic nucleus (STN) and the pedunculopontine tegmental nucleus (PPTg). Here we describe the cognitive test performance and the corresponding cortical metabolic activity, as assessed through 18-fluorodeoxyglucose (FDG)-positron emission tomography (PET), of these six PD patients tested in PPTg-ON vs- PPTg-OFF condition.

PPTg-ON condition (at low frequency, 25 Hz) induced better performance in tests exploring both executive and attentive domains, which were coupled with an increased glucose utilization in prefrontal and frontal bilateral cortical areas, including both lateral (i.e., BA 9) and more antero-medial cortices (BA 25–32). Moreover, during PPTg-ON, a surprising increase of FDG consumption was also observed in the left ventral striatum.

These data are consistent with the hypothesis of a positive effect of 25 Hz PPTg-DBS on PD patients' cognitive profile, probably due to a facilitatory effect exerted by PPTg on both associative and limbic pathways.
Dopamine, Reward, and Frontostriatal Circuitry in Impulse Control Disorders in Parkinson's Disease: Insights from Functional Imaging
Authors: Ray Nicola , Strafella Antonio P.
Published: February 2012

Dopamine agonists have been implicated in the development of impulse control disorders (ICDs). This may be due to the ability of agonists to tonically stimulate dopamine receptors. Recent neuro-imaging data provided evidence that dopamine agonists induce significant changes in those frontostriatal circuits that process reward and mediate our ability to control impulses. Tonic stimulation of dopa-mine receptors via agonists may impair reward processing and inhibitory control mechanisms in ways that promote pathological repetition of behaviors. We will provide an overview of the current understanding of the neurobiology underlying ICDs in Parkinson's disease (PD).
A Combined rTMS and ERP Investigation of Dorsolateral Prefrontal Cortex Involvement in Response Inhibition
Authors: Upton Daniel J. , Cooper Nicholas R. , Laycock Robin , Croft Rodney J. , Fitzgerald Paul B.
Published: February 2012

The stop signal task is used to investigate inhibition of an initiated response. Converging evidence suggests that right inferior prefrontal cortex is involved in this behavior, although other regions in the prefrontal cortex have also been implicated. One technique used to determine the contribution of specific cortical regions to behavior is repetitive transcranial magnetic stimulation (rTMS). In the present study, fourteen subjects performed the stop signal task before and after receiving a train of rTMS to the left and right dorsolateral prefrontal cortex (DLPFC). The effects of rTMS were determined using event-related potential (ERP) measures that have been associated with response inhibition in previous studies. Stimulation of left and right DLPFC did not affect ERP measures of response inhibition. This negative finding is interpreted with caution, but is consistent with a recent study which found that stimulation of the same region had no effect on a behavioral measure of response inhibition.
Quantitative Electroencephalographic Abnormalities in Fibromyalgia Patients
Authors: Hargrove Jeffrey B. , Bennett Robert M. , Simons David G. , Smith Susan J. , Nagpal Sunil , Deering Donald E.
Published: February 2012

There is increasing acceptance that pain in fibromyalgia (FM) is a result of dysfunctional sensory processing in the spinal cord and brain, and a number of recent imaging studies have demonstrated abnormal central mechanisms. The objective of this report is to statistically compare quantitative electroencephalogram (qEEG) measures in 85 FM patients with age and gender matched controls in a normative database.

A statistically significant sample (minimum 60 seconds from each subject) of artifact-free EEG data exhibiting a minimum split-half reliability ratio of 0.95 and test-retest reliability ratio of 0.90 was used as the threshold for acceptable data inclusion. FM subject EEG data was compared to EEGs of age and gender matched healthy subjects in the Lifespan Normative Database and analyzed using NeuroGuide 2.0 software. Analyses were based on spectral absolute power, relative power and coherence. Clinical evaluations included the Fibromyalgia Impact Questionnaire (FIQ), Beck Depression Inventory and Fischer dolorimetry for pain pressure thresholds.

Based on Z-statistic findings, the EEGs from FM subjects differed from matched controls in the normative database in three features: (1) reduced EEG spectral absolute power in the frontal International 10–20 EEG measurement sites, particularly in the low- to mid-frequency EEG spectral segments; (2) elevated spectral relative power of high frequency components in frontal / central EEG measurement sites; and (3) widespread hypocoherence, particularly in low- to mid-frequency EEG spectral segments, in the frontal EEG measurement sites. A consistent and significant negative correlation was found between pain severity and the magnitude of the EEG abnormalities. No relationship between EEG findings and medicine use was found.

It is concluded that qEEG analysis reveals significant differences between FM patients compared to age and gender matched healthy controls in a normative database, and has the potential to be a clinically useful tool for assessing brain function in FM patients.
Electrophysiological Characteristics of Seizure Clusters
Authors: Tripathi M. , Singh P.K. , Vibha D. , Choudhary N. , Garg A. , Bal C.S. , Sarkar C. , Bhatia R. , Padma M.V. , Gaikwad S. , Singh M.B. , Prasad K. , Chandra P.S.
Published: February 2012

The phenomenon of temporal clustering of seizures is well known, but its effect on seizure localization has not been rigorously analyzed. The aim of our study was to assess electrophysiological localization during Video EEG (VEEG) monitoring in patients with intractable epilepsy demonstrating a cluster of seizures.

The study was conducted on 203 intractable epilepsy patients, aged 2 to 60 years (19.96 ± 10.87). Patients with unilateral temporal lobe epilepsy having clusters were compared with patients not having clusters, and the effect of clustering on concordance was addressed.

Fully consistent localization was observed in 116 patients, partially consistent localization in 18 patients, and inconsistent localization in 19 patients. ANOVA did not reveal any significant difference in these groups (p = 0.65). A total of 770 seizures recorded from 149 patients was analyzed for clustering effect. Clustering was present in 603/770 seizures pairs (78.31%). In the cluster group, 483 (80.09%) seizure pairs were concordant for seizure onset, while 98 (16.25%) were discordant and 22 (3.65%) were indeterminate. In the noncluster group, 134 (80.24%) seizure pairs were concordant for seizure onset, while 23 (13.77%) were discordant and 10 (5.98%) were indeterminate. The study found that cluster seizures occurring within an interseizure interval (ISI) less than 8 hours are independent and have the same localizing value as those seizures with longer ISIs.
Hemispheric Lateralization in Benign Focal Epilepsy in Childhood with Centrotemporal Spikes (BECTS)
Authors: Miziara C.S.M.G. , Manreza M.L.G.
Published: February 2012

Benign focal epilepsy in childhood with centrotemporal spikes (BECTS) is one of the most common forms of epilepsy. In adults there is a higher percentage of lateralized epileptic discharges in the left cerebral hemisphere; however, in children this pattern does not seem to have the same distribution. The objective of this study was to evaluate the lateralization of interictal spikes in children with BECTS in relation to the sex of the child and the age of onset of epilepsy. We studied the electroencephalograms (EEGs) of 114 children with a clinical diagnosis of BECTS according to ILAE. The results obtained from two EEGs, performed at intervals of 6 and 12 months, were correlated with the age of onset of the epileptic seizures and the sex of the child. There was no association between the onset of epileptic seizures and the age of the child (p = 0.461). When we analyzed the relationship between laterality and sex we did not observe any difference in the first EEG (p = 0.767) results; however, in the results of the second EEG there was a difference (p = 0.002). In males, left and bilateral interictal spikes were predominant, and in females the right hemisphere showed predominant spikes and there were continuous spike-and-wave discharges during slow sleep (CSWSS). The analysis between laterality and a child's age did not show predominant interictal spikes in the hemispheres, except in males where there were predominant multifocal and generalized spikes, but not lateralization (p = 0.011).

The conclusion was that in BECTS the lateralization of interictal spikes was not consistent as described in adult patients, but there was a slight left hemispheric predominance in boys and right hemispheric predominance in girls.
Neural Correlates of Error Monitoring in an Adult with Klinefelter's Syndrome: A Case Report
Authors: Chang Wen-Pin
Published: February 2012

Studies have indicated that individuals with Klinefelter's syndrome (KS) exhibit deficits in executive functions. However, little attention has been paid to investigate control mechanism of executive functions, i.e., error monitoring, in individuals with KS. Two event-related potential (ERP) components, i.e., error-related negativity (Ne/ERN) and error positivity (Pe), are the electrophysiological markers of error monitoring. This case report presents the findings of error monitoring from an adult with KS using the electrophysiological technique. This KS individual displayed small ERN and Pe amplitudes, suggesting that he may exhibit deficient error detection and reaction, a lack of conscious error recognition, and nonproficient adjustment after an error. The findings of this report should stimulate further study in error monitoring in individuals with KS.
Noninvasive Multimodal Neuroimaging for Rasmussen Encephalopathy Surgery: Simultaneous EEG-fMRI Recording
Authors: Bravo E.R. Cuspineda , Iturria Y. , Praderes J.C. , Melie L. , Valdés P.A. , Virues T. , Machado C. , Urrutia L. Valdés
Published: February 2012

Rasmussen syndrome is characterized by continuous partial seizures with progressive neurological/cognitive impairment. Currently the only effective treatment is surgery (hemispherectomy). The objective of our study is to detect the exact epileptogenic focus through the analysis of multimodal noninvasive and innocuous functional neuroimaging.

The subject is a 5-year-old female patient with Rasmussen encephalopathy. Continuous and simultaneous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) was record ed. The sources of background and paroxysmal activity of EEG were computed by low resolution electromagnetic tomography (LORETA). Image analysis (SPM: statistic parametric mapping) was obtained for the areas where statistically significant differences in the fMRI BOLD response were computed, and the results from both techniques were compared.

The main source of paroxysmal activity by EEG analysis was found in the anterolateral left hemisphere, with a significant increase in absolute and relative energies of slow frequency bands (theta-delta): Z ≥ 3. The fMRI BOLD signal (basal vs. paroxysmal activity) was significantly different in the same region (t-test ≥ 2.39). The generators of propagated paroxysmal activity were found in similar areas for both techniques.

In conclusion, simultaneous EEG-fMRI recording allows the analysis of two harmless functional neuroimaging techniques separately and together in the same time period. In our case, it allowed the accurate delineation of epileptogenic foci and areas of spread with high spatiotemporal resolution, which is crucial for epilepsy surgery.
The Yield of Preoperative Sequential Routine Scalp EEGs in Patients Who Underwent Anterior Temporal Lobectomy for Mesial Temporal Sclerosis
Authors: Dericioglu Nese , Colpak Ayse Ilksen , Ciger Abdurrahman , Saygi Serap
Published: February 2012

Mesial temporal lobe epilepsy syndrome (MTLES) is the most common surgically remediable epileptic syndrome in adults. Its diagnosis is easy when clinical history is supported by positive laboratory findings. However, routine EEG may not be informative in some patients, thus delaying accurate diagnosis. Therefore, we sought to determine how often routine EEGs displayed epileptiform discharges pre-operatively in a group of patients who underwent surgery for MTLES.

Retrospectively, we reviewed the outpatient EEG records of MTLES patients who underwent surgery at our epilepsy center between 1997–2008 and had at least one routine pre-operative EEG recording in our outpatient laboratory. For each patient, serial EEGs were coded as normal, displaying nonspecific abnormalities or lateralized and localized interictal epileptiform discharges.

Seventy patients were included in the study. We reviewed 230 EEGs. In almost half of the patients (47.1%) all EEGs were normal or revealed nonspecific findings. In patients who had >1 EEG, almost 3 EEGs had to be recorded to detect the epileptiform discharges for the first time and 6.23 years were needed to accomplish this. Sleep deprivation considerably increased the yield.

In summary, patients who have a clinical history suggesting MTLES may need at least 3 routine scalp EEG recordings (with at least one of them after sleep deprivation) to detect epileptiform abnormalities and it may take much time. Therefore, a single prolonged outpatient video-EEG monitoring or an overnight inpatient monitoring might be reasonable alternatives to serial EEGs.