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Results for “Cortical Synchronization”

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At least 1,405 records · Page 78Linked to original sources
PubMed1980

Right hemisphere dominance for attention: the mechanism underlying hemispheric asymmetries of inattention (neglect).

Because hemiinattention is most commonly caused by right parietal lesions, it is possible that the left hemisphere attends to contralateral stimuli whereas the right attends to both contralateral and ipsilateral stimuli. We gave lateralized visual stimuli to 12 normal subjects and recorded the electroencephalograms. Desynchronization was determined by comparing the alpha power 1 second before and 1 second after a lateralized visual stimulus. Although the left parietal lobe desynchronized most after right-sided stimuli, the right parietal lobe desynchronized equally after right or left stimuli. These findings support the hypothesis that the right hemisphere is dominant for attention.

Adolescent↗
PubMed1981

Subacute sclerosing panencephalitis: atypical absence attacks as first symptom.

Subacute sclerosing panencephalitis was diagnosed in a 10-year-old girl who had suffered from atypical absence attacks for 3 months; diagnosis was made after 5 months of these attacks. Characteristic EEG findings included diffuse spike and wave complexes of about 2.5 Hz associated with desynchronization during the absence attacks, and recruiting rhythm during the tonic seizure. As the lesion responsible for these EEG patterns originated in the brainstem, subcortical structures were probably affected early in the disease. The SSPE complexes may have originated chiefly in the brainstem since, in this case, they were recognized even during the period of absence attacks.

Brain Stem↗
PubMed1975

Human auditory nerve responses: a comparison of three commonly used recording sites.

The computer-averaged N1 response from humans to click stimuli was compared at three recording sites -- dermal and subdermal electrodes in the ear canal, and a transtympanic electrode on the promontory. A total of 26 subjects, some of whom were measured at all three sites, participated in 47 experiments. The promontory electrodes were consistently more sensitive and yielded cleaner N1 waveforms than did the ear canal sites. In considering the clinical use of N1 averaging, the advantages of the transtympanic method outweigh the risks. While a few persons yield reasonable good ear canal potentials, the reliablitity of this method in general application is inadequate and unpredictable.

Audiometry↗
PubMedDate not supplied

Frequency component selection for an ECoG-based brain-computer interface.

The aim of the present study was to investigate the most significant frequency components in electrocorticogram (ECoG) recordings in order to operate a brain computer interface (BCI). For this purpose the time-frequency ERD/ERS map and the distinction sensitive learning vector quantization (DSLVQ) are applied to ECoG from three subjects, recorded during a self-paced finger movement. The results show that the ERD/ERS pattern found in ECoG generally matches the ERD/ERS pattern found in EEG recordings, but has an increased prevalence of frequency components in the beta range.

Brain Mapping↗
PubMed1997

Cardiovascular and respiratory changes during slow-wave sleep in rats are associated with electrocorticogram desynchronization.

In awake rats a single recurrent larger tidal volume (deep breaths) occurs at regular intervals, followed by oscillations in arterial pressure and heart rate. In the present study we recorded the changes in blood pressure, heart rate and ventilation during the wakefulness-sleep cycle identified by electrocorticographic records in order to determine whether the deep breaths and cardiovascular oscillations were associated with changes in the electrocorticogram. During several episodes of slow-wave sleep (SWS) in 7 rats the deep breaths and oscillations in arterial pressure and heart rate were preceded by SWS desynchronization. The interval between deep breaths during SWS was 71 +/- 4 s, the period between initial desynchronization and the generation of deep breaths was 3.98 +/- 0.45 s and the duration of SWS desynchronization was 11 +/- 0.65 s. Hypotension (-16 +/- 1 mmHg) and tachycardia (+15 +/- 5 bpm) were observed during deep breaths in the SWS state. These data indicate that the oscillations in arterial pressure and heart rate during SWS are associated with deep breaths, which in turn are preceded by desynchronization of the electrocorticogram in this state of sleep.

Animals↗
PubMed1979

A finite state model for meditation phenomena.

Various reports of brain wave synchrony during Transcendental Meditation have appeared in the literature and have been interpreted as indicating a heightened state of integration of brain function. We suggest that this observed synchrony rather than indicating a greater integration of brain function might be an artifact of parts of the brain acting like a finite state machine. The finite state model is developed, its properties derived and a test for the hypothesis is presented.

Cerebral Cortex↗
PubMed2003

EEG alpha desynchronization in musicians and nonmusicians in response to changes in melody, tempo, and key in classical music.

Two experiments were performed to examine musicians' and nonmusicians' electroencephalographic (EEG) responses to changes in major dimensions (tempo, melody, and key) of classical music. In Exp. 1, 12 nonmusicians' and 12 musicians' EEGs during melody and tempo changes in classical music showed more alpha desynchronization in the left hemisphere (F3) for changes in tempo than in the right. For melody, the nonmusicians were more right-sided (F4) than left in activation, and musicians showed no left-right differences. In Exp. 2, 18 musicians' and 18 nonmusicians' EEG after a key change in classical music showed that distant key changes elicited more right frontal (F4) alpha desynchronization than left. Musicians showed more reaction to key changes than nonmusicians and instructions to attend to key changes had no significant effect. Classical music, given its well-defined structure, offers a unique set of stimuli to study the brain. Results support the concept of hierarchical modularity in music processing that may be automatic.

Adolescent↗
PubMed1984

Electrocortical activity and related phenomena associated with meditation practice: a literature review.

The state effects of meditation appear to include decreased electrocortical arousal. There is also evidence that meditators more readily demonstrate alpha and theta activity than nonmeditators, even when not meditating. It is not clear whether prospective meditators as a group already possessed this characteristic, or whether the state effects of meditation practice eventually generalize to become traits. However, certain individuals, namely the psychologically "healthy" and those with a capacity for relaxed absorbed attention, appear to be more favourably disposed to meditation. Meditators appear to show both stronger orienting and recovery responses to stressors while meditating than controls. Meditation practice may begin with left hemisphere type activity, which gives way to functioning more characteristic of the right hemisphere. However, it appears that during advanced meditation ("no thought") both left and right hemisphere activity are largely inhibited or suspended. Depending on the individual, inexperienced meditators may report sleep, hypnogogic reverie, trance or abreaction during practice. The evidence to date does not support the notion of unique state effects associated with the practice of meditation.

Alpha Rhythm↗
PubMed1987

The pattern and habituation of the orienting response in man and rats.

Autonomic and central nervous indices of the orienting response (OR) were investigated in awake human subjects and sleeping rats. Ten acoustic stimuli of 60 dB and two stimuli of 80 dB were presented for 10 s each with a constant interstimulus interval of 50 s. Responses were averaged across subjects for each single trial. An exponential fit to scores of each physiological variable was used to compare OR, habituation and dishabituation between samples and variables. An OR to the first stimulus, habituation of response amplitude, and dishabituation in response to the change in stimulus intensity were observed for event-related EEG desynchronization, a negative-positive evoked potential complex in humans and rats, as well as for skin conductance in humans. While heart rate did not show systematic changes across the 60 dB tones in both samples, a deceleration was observed in response to the first 80 dB tone. Results suggest comparable patterns of orienting to acoustic stimuli and habituation of the OR in the awake human and the sleeping rat, suggesting the possibility of OR as a unitary response. Species differed with respect to speed of habituation but not with respect to sensitivity towards stimulus change.

Acoustic Stimulation↗