Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cortical Synchronization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,387 records · Page 77Linked to original sources
PubMed1975

Psychomotor activity as a correlate of Depression and sleep in acutely disturbed psychiatric inpatients.

Combining a lightweight telemetric mobility sensing system with nightly EEG-sleep recordings, the authors obtained continuous monitoring of rest-activity cycles among psychiatric patients hospitalized for primary depression or acute schizophreniform thought disorder. The patients with primary depression had a significantly higher percentage of their total 24-hour motor activity distributed during the night. Furthermore, this increased nocturnal motor activity did not correlate significantly with concurrent EEG-sleep measures of wakefulness. Indeed, the best predictors of wakefulness were measures of daytime activity. This desynchronization of sleep and nighttime motor activity in primary depression may explain the need for combined pharmacotherapy in some severely depressed patients. The authors suggest that expressing activity as a percentage distribution function, rather than in terms of absolute amplitude, provides an objective diagnostic index of depression.

Acute Disease↗
PubMed1977

On the safety of long-term treatment with lithium.

Thirteen patients with bipolar affective illness who had received lithium therapy for 1-5 years were tested retrospectively for evidence of cortical dysfunction. Data on patients younger than 55 show no abnormalities on the Halstead-Reitan Neuropsychological Battery and suggest that chronic lithium therapy is relatively safe. Significantly elevated Halstead Impairment indexes were observed among elderly patients, but these data are difficult to interpret.

Adolescent↗
PubMed1998

Preliminary evidence for aberrant cortical development in abused children: a quantitative EEG study.

The objectives of this study were to investigate cortical development and hemispheric asymmetry in abused children. Fifteen hospitalized children (mean age 10.7 +/- 2.5 years) with severe physical or sexual abuse and 15 normal children (10.1 +/- 3.1 years) were studied with quantitative EEG. Abused children had higher levels of left hemisphere coherence and a reversed asymmetry, with left hemisphere coherence significantly exceeding right hemisphere coherence. Left hemisphere coherence decreased more rapidly across electrode distance in normal subjects, suggesting that increased left coherence in abused patients stemmed from a deficit in left cortical differentiation. These findings support the hypothesis that early severe abuse may have a deleterious effect on brain development.

Adolescent↗
PubMed1998

Sleep bruxism is a disorder related to periodic arousals during sleep.

There is evidence that sleep bruxism is an arousal-related phenomenon. In non-REM sleep, transient arousals recur at 20- to 40-second intervals and are organized according to a cyclic alternating pattern. Polysomnographic recordings from six subjects (two females and four males) affected by sleep bruxism (patients) and six healthy age-and gender-matched volunteers without complaints about sleep (controls) were analyzed to: (1) compare the sleep structure of bruxers with that of non-complaining subjects; and (2) investigate the relations between bruxism episodes and transient arousals. Patients and controls showed no significant differences in conventional sleep variables, but bruxers showed a significantly higher number of the transient arousals characterized by EEG desynchronization. Bruxism episodes were equally distributed between non-REM and REM sleep, but were more frequent in stages 1 and 2 (p < 0.0001) than in slow-wave sleep. The great majority of bruxism episodes detected in non-REM sleep (88%) were associated with the cyclic alternating pattern and always occurred during a transient arousal. Heart rate during the bruxism episodes (69.3+/-18.2) was significantly higher (p < 0.0001) than that during the pre-bruxing period (58.1+/-15.9). Almost 80% of all bruxism episodes were associated with jerks at the anterior tibial muscles. The framework of the cyclic alternating pattern offers a unified interpretation for sleep bruxism and arousal-related phenomena.

Adult↗
PubMed1985

Effect of the standardized Ginseng Extract G115 on the metabolism and electrical activity of the rabbit's brain.

The objective of this original investigation was to study the effect of the standardized Ginseng Extract G115 on the metabolic activity and ECoG of the rabbit's brain. The results showed significant increase of the glucose uptake with simultaneous significant reduction of the lactate, pyruvate and lactate/pyruvate ratio. These findings indicate shift of glucose utilization by the drug from anaerobic to the more economical pathway. G115 was also shown to produce a desynchronizing effect on the electrocorticogram (ECoG) which correlated well with the biochemical findings.

Animals↗
PubMed1992

Staring episodes in children analyzed by telemetry.

Staring episodes in children may be ictal or nonictal, and telemetry helps make this distinction. Twenty-seven children referred to our service for elucidating the nature of their staring spells were studied by telemetry. No staring events were recorded in four children. The staring events were not associated with electroencephalographic (EEG) changes in 12 children. In 11 children, the staring events had EEG accompaniments: four had generalized spike-and-wave changes; three had focal or asymmetrical changes; and four had generalized decrement (desynchronization), which has not been described before as an electrical correlate of staring. EEG video telemetry in this group of patients led to accurate diagnosis and appropriate medical, surgical or behavioral management.

Adolescent↗
PubMed2006

Electromagnetic correlates of recognition memory processes.

Recognition memory is critically dependent on a hierarchically organized network of brain areas including the visual ventral stream, medial temporal lobe structures, frontal and parietal cortices. In recent years, cognitive theories of recognition memory have been helpful to further our understanding of the functional organization of this network. A prominent, although not unchallenged, set of theories proposes that recognition memory is not a unitary phenomenon, but can be based on the recollection of contextual information about events or on familiarity in the absence of recollection. A number of hemodynamic and electromagnetic studies have been undertaken to relate recollection and familiarity to neuronal substrates both in healthy subjects as well as in patients with brain lesions. Today, it is evident that both event-related potential and event-related field (ERP/ERF) data as well as data of oscillatory brain activity (e.g., theta oscillations) are necessary to fully understand the neural dynamics of recollection and familiarity and their relationship to functional anatomy. Ultimately, such data are required from patients with isolated brain injuries to designated components of the networks (such as the hippocampus) to obtain converging evidence for functional relationships between recollection and familiarity and respective neuroanatomic substrates. The complexity of this task is highlighted by findings indicating that recognition memory can already be affected by preparatory processes prior to stimulus onset.

Amnesia↗
PubMed1993

Quantification of alpha rhythm desynchronization using the acceleration spectrum entropy of the EEG.

Desynchronization of the alpha rhythm is usually quantified as a loss of power in the alpha band. In this study we describe an alternative approach where desynchronization is characterized as an increase in the irregularity of the EEG signal. A new measure, the acceleration spectrum entropy (ASE), is used to quantify EEG irregularity. The ASE is the normalized information entropy of the amplitude spectrum of the second derivative of a time series. The ASE is a measure of the randomness or irregularity of a time series and ranges from 0 (straight line) to 100 (discrete random signal). The ASE was calculated for short EEG epochs under eyes closed and eyes open conditions in 15 subjects. There was a significant increase in ASE in the eyes open condition, reflecting an increase in EEG complexity. The ASE is a sensitive measure of EEG desynchronization.

Alpha Rhythm↗
PubMed1994

EEG changes during mental activation.

Desynchronization of the EEG in relation to mental activity can be demonstrated through various means. The acceleration spectrum entropy (ASE) is a method that quantifies the desynchronization of the EEG. It is a measure of the randomness or irregularity of a time series and ranges from 0 (straight line) to 100 (discrete random signal). The ASE was calculated for 20 EEGs under four conditions: "eyes closed," "eyes open," "eyes closed and mental arithmetic" and "eyes open and mental arithmetic." There was a significant increase between the conditions "eyes closed" and "eyes open" and a significant increase between the conditions "eyes closed" and "eyes closed and mental arithmetic." During eye opening the largest increase was seen in the occipital areas. Mental arithmetic showed an asymmetrical increase, namely in the left temporo-occipital region and in the right centro-temporal region. It is suggested that the ASE can be used to study cortical activation due to mental activity.

Algorithms↗
PubMed1995

Specific patterns of cortical dysfunction in dementia and Parkinson's disease demonstrated by the acceleration spectrum entropy of the EEG.

Acceleration spectrum entropy (ASE) was used to quantify EEG desynchronization, which is related to cortical activation. We investigated the ASE in control and patient groups with dementia (AD) and Parkinson's disease (PD). Both patient groups had significantly lower ASE scores corresponding with less desynchronization in all cortical regions. In the AD group, the ASE was significantly lower in the parietal region. ASE was found to be a sensitive and specific measure for differentiating patient groups with AD and PD from controls and from each other.

Aged↗
PubMed1997

Decreased multi-band posterior interhemispheric coherence with a lipoma on the corpus callosum: a case report of a possible association.

The corpus callosum plays a role in mediating interhemisphere communication. Coherence may be a quantitative EEG-based measure of this communication. The present report is of a female schizophrenic patient with a marked coherence deficit in the temporal-parietal-occipital region involving multiple frequency bands. An MRI scan of her brain revealed a lipoma involving the splenium of the corpus callosum. It is speculated that this lipoma may have caused a physical impingment on or developmental aberration of adjacent callosal fibers, resulting in the observed coherence deficit. Further studies of coherence measures in patients with collosal lipomas are proposed.

Adult↗
PubMed1997

Frontal lobe epilepsy with secondarily generalized 3 Hz spike-waves: a case report.

We report a case of frontal lobe epilepsy with bursts of 3 Hz spike-wave, often dominant in the left frontal lobe, that sometimes developed into a secondary bilateral generalization. This patient was a 69-year-old male with a history of epileptic seizures that began 3 months following a head injury at the age of 17. His seizures occurred two or three times a day, but after medication the frequency was halved. The seizures began with a feeling of heaviness of the head, accompanied by myoclonus at both angles of the mouth. Consciousness was clear for most of the seizures, which ranged from several seconds to many minutes. When seizures lasted for longer than 10 minutes, a temporary generalization accompanied by a loss of consciousness was sometimes observed. Neurological tests and cranial MRI yielded no abnormal local findings. The secondary generalized seizure seen in this case is the so called "secondary bilateral synchrony (SBS)." We succeeded in making an EEG recording of the bilateral generalization of a seizure discharge originating in the left frontal lobe, which until now has not been done. This case is direct proof that a primary frontal focus can give rise to SBS.

Aged↗
PubMed2005

The influence of methylphenidate on the power spectrum of ADHD children - an MEG study.

BACKGROUND: The present study was dedicated to investigate the influence of Methylphenidate (MPH) on cortical processing of children who were diagnosed with different subtypes of Attention Deficit Hyperactivity Disorder (ADHD). As all of the previous studies investigating power differences in different frequency bands have been using EEG, mostly with a relatively small number of electrodes our aim was to obtain new aspects using high density magnetoencephalography (MEG). METHODS: 35 children (6 female, 29 male) participated in this study. Mean age was 11.7 years (+/- 1.92 years). 17 children were diagnosed of having an Attention-Deficit/Hyperactivity Disorder of the combined type (ADHDcom, DSM IV code 314.01); the other 18 were diagnosed for ADHD of the predominantly inattentive type (ADHDin, DSM IV code 314.0). We measured the MEG during a 5 minute resting period with a 148-channel magnetometer system (MAGNES 2500 WH, 4D Neuroimaging, San Diego, USA). Power values were averaged for 5 bands: Delta (D, 1.5-3.5 Hz), Theta (T, 3.5-7.5 Hz), Alpha (A, 7.5-12.5 Hz), Beta (B, 12.5-25 Hz) and Global (GL, 1.5-25 Hz).). Additionally, attention was measured behaviourally using the D2 test of attention with and without medication. RESULTS: The global power of the frequency band from 1.5 to 25 Hz increased with MPH. Relative Theta was found to be higher in the left hemisphere after administration of MPH than before. A positive correlation was found between D2 test improvement and MPH-induced power changes in the Theta band over the left frontal region. A linear regression was computed and confirmed that the larger the improvement in D2 test performance, the larger the increase in Theta after MPH application. CONCLUSION: Main effects induced by medication were found in frontal regions. Theta band activity increased over the left hemisphere after MPH application. This finding contradicts EEG results of several groups who found lower levels of Theta power after MPH application. As relative Theta correlates with D2 test improvement we conclude that MEG provide complementary and therefore important new insights to ADHD.

Alpha Rhythm↗
PubMed2003

Nitric oxide is involved in the expression of neocortical spike-and-wave spindling episodes in DBA/2J mice.

This study investigated the possible role of nitric oxide (NO) in the development of neocortical spike-and-wave spindling episodes (S&W) of DBA/2J mice. The administration of distilled water did not modify either the number or duration of S&W in DBA/2J mice during the whole recording period (240 min). L-N(G)-nitro arginine methyl ester (L-NAME) (3-300 microg/mouse, i.c.v.) dose-dependently reduced the S&W of DBA/2J mice. This effect appeared 30 min after drug administration and lasted for the duration of the recording period (240 min). In addition, L-NAME treatment did not induce significant alterations of stereotyped behaviour such as licking, sniffing, chewing or tremors of the head and body and behavioural excitability, whereas the electroencephalogram desynchronized pattern was also significantly reduced. By contrast D-N(G)-nitro arginine methyl ester at the same doses did not affect S&W of mice. The inhibitory effect of L-NAME on S&W of mice was dose-dependently reversed by L-arginine (L-ARG, 3-300 microg/mouse, i.c.v.) but not by D-arginine. Finally, glyceryl trinitrate on its own (3-300 microg/mouse, i.c.v.) significantly increased the S&W of mice and it was also able to reverse the inhibition on S&W of mice operated by L-NAME. These results provide evidence that NO may play a significant role in the development of brain excitability.

Animals↗