Neuromagnetic Changes of Brain Rhythm Evoked by Intravenous Olfactory Stimulation in Humans
Ai MiyanariYoshiki KaneokeAya IharaShoko WatanabeYasuhiro OsakiTakeshi KuboAmami KatoToshiki YoshimineYoshimitsu SagaraRyusuke Kakigi
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To identify the changes in the respective frequency band and brain areas related to olfactory perception, we measured magnetoencephalographic (MEG) signals before and after instilling intravenously thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disulfide monohydrochloride (TTFD), which evoked a strong and weak sensation of odor, respectively. For the frequency analysis of MEG, a beamformer program, synthetic aperture magnetometry (SAM), was employed and event-related desynchronization (ERD) or synchronization (ERS) was statistically determined. Both strong and weak odors induced ERD in (1) beta band (13–30 Hz) in the right precentral gyrus, and the superior and middle frontal gyri in both hemispheres, (2) low gamma band (30–60 Hz) in the left superior frontal gyrus and superior parietal lobule, and the middle frontal gyrus in both hemispheres, and (3) high gamma band 2 (100–200 Hz) in the right inferior frontal gyrus. TPD induced ERD in the left temporal, parietal and occipital lobes, while TTFD induced ERD in the right temporal, parietal and occipital lobes. The results indicate that physiological functions in several regions in the frontal lobe may change and the strength of the odor may play a different role in each hemisphere during olfactory perception in humans.Keywords:
Magnetoencephalography
Superior frontal gyrus
Limbic lobe
Magnetoencephalography
Brain Function
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Objective To explore the location of frontal gyrus by the processus neuralis in transection,to provide morphological data for imageology.Methods Twenty normal cadaver heads were chose,6 mm brain slices were cut after stained superior frontal gyrus,middle frontal gyrus,inferior frontal gyrus,chose the typical planes to observe and measure the relation between processus neuralis and superior frontal gyrus,middle frontal gyrus,inferior frontal gyrus on horizontal sections and summarize the rules.Results The processus neuralis on direction of 12:00-12:30 hour hand were corresponding to superior frontal gyrus.The processus neuralis on direction of 12:30-1:00 hour hand(right side),and 10:30-11:30 hour hand(right side) were corresponding to middle frontal gyrus.The processus neuralis on direction of 2:00-3:00 hour hand(right side),and 9:00-11:00 hour hand(right side) were corresponding to inferior frontal gyrus.Conclusion The corresponding rules between processus neuralis and superior frontal gyrus,middle frontal gyrus,inferior frontal gyrus are obtained.So it may localize superior frontal gyrus,middle frontal gyrus,inferior frontal gyrus by processus neuralis on image.
Superior frontal gyrus
Limbic lobe
Inferior frontal gyrus
Middle frontal gyrus
Gyrus
Medial frontal gyrus
Frontal lobe
Superior temporal gyrus
Middle temporal gyrus
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Abstract Although magnetoencephalography (MEG) and electroencephalography (EEG) have been available for decades, their relative merits are still debated. We examined regional differences in signal‐to‐noise‐ratios (SNRs) of cortical sources in MEG and EEG. Data from four subjects were used to simulate focal and extended sources located on the cortical surface reconstructed from high‐resolution magnetic resonance images. The SNR maps for MEG and EEG were found to be complementary. The SNR of deep sources was larger in EEG than in MEG, whereas the opposite was typically the case for superficial sources. Overall, the SNR maps were more uniform for EEG than for MEG. When using a noise model based on uniformly distributed random sources on the cortex, the SNR in MEG was found to be underestimated, compared with the maps obtained with noise estimated from actual recorded MEG and EEG data. With extended sources, the total area of cortex in which the SNR was higher in EEG than in MEG was larger than with focal sources. Clinically, SNR maps in a patient explained differential sensitivity of MEG and EEG in detecting epileptic activity. Our results emphasize the benefits of recording MEG and EEG simultaneously. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Magnetoencephalography
EEG-fMRI
SIGNAL (programming language)
Brain mapping
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A single session of heart rate variability (HRV) biofeedback in apparently healthy young people and adolescents aged 14-17 years in order to increase vagal effects on heart rhythm and also electroencephalograms were carried out. Different variants of EEG spectral power during the successful HRV biofeedback session were identified. In the case of I variant of EEG activity the increase of power spectrum of alpha-, betal-, theta-components takes place in all parts of the brain. In the case of II variant of EEG activity the reduction of power spectrum of alpha-, betal-, theta-activity in all parts of the brain was observed. I and II variants of EEG activity cause more intensive regime of cortical-subcortical interactions. During the III variant of EEG activity the successful biofeedback is accompanied by increase of alpha activity in the central, front and anteriofrontal brain parts and so indicates the formation of thalamocortical relations of neural network in order to optimize the vegetal regulation of heart function. There was an increase in alpha- and beta1-activity in the parietal, central, frontal and temporal brain parts during the IV variant of EEG activity and so that it provides the relief of neural networks communication for information processing. As a result of V variance of EEG activity there was the increase of power spectrum of theta activity in the central and frontal parts of both cerebral hemispheres, so it was associated with the cortical-hippocampal interactions to achieve a successful biofeedback.
Biofeedback
Alpha (finance)
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We studied visual perception using an annular random-dot motion stimulus called the racetrack. We recorded neural activity using magnetoencephalography while subjects viewed variants of this stimulus that contained no inherent motion or various degrees of embedded motion. Subjects reported seeing rotary motion during viewing of all stimuli. We found that, in the absence of any motion signals, patterns of brain activity differed between states of motion perception and nonperception. Furthermore, when subjects perceived motion, activity states within the brain did not differ across stimuli of different amounts of embedded motion. In contrast, we found that during periods of nonperception brain-activity states varied with the amount of motion signal embedded in the stimulus. Taken together, these results suggest that during perception the brain may lock into a stable state in which lower-level signals are suppressed.
Magnetoencephalography
Stimulus (psychology)
Neural Activity
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Recent advances in migraine research have shown that the cerebral cortex serves a primary role in the pathogenesis of migraine. Since aberrant brain activity in migraine can be noninvasively detected with magnetoencephalography (MEG), The object of this study was to investigate the resting state cortical activity differences between migraineurs and controls and its related clinical characteristics.Twenty-two subjects with an acute migraine and twenty-two age- and gender-matched controls were studied using MEG. MEG recordings were recorded 120 seconds during the headache attack. Analyze MEG signals from low (1-4 Hz) to high (200-1000 Hz)-frequency ranges.In comparison with the controls, brain activity in migraine subjects was significantly different from that of the controls both in two frequency ranges (55-90 Hz, p < 0.001) and (90-200 Hz, p < 0.004). But the power value showed no significantly differences between control and migraines in all frequency ranges (p > 0.05). All the clinical characteristics had no significant correlation with aberrant brain activity.The results demonstrated that migraine subjects in resting state had significantly aberrant ictal brain activity that can be measured with neuromagnetic imaging techniques. The findings may facilitate the development of new therapeutic strategies in migraine treatment via alterations in cortical excitability with TMS and other medications in the future.
Magnetoencephalography
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Electrical cortical stimulation (CS) of the auditory cortices has been shown to reduce the severity of debilitating tinnitus in some patients. In this study, we performed MEG source imaging of spontaneous brain activity during concurrent CS of the left secondary auditory cortex of a volunteer suffering from right unilateral tinnitus. CS produced MEG artifacts which were successfully sorted and removed using a combination of sensor and source level signal separation and classification techniques. This contribution provides the first proof of concept reporting on analysis of MEG data with concurrent CS. Effects of CS on ongoing brain activity were revealed at the MEG sensor and source levels and indicate CS significantly reduced ongoing brain activity in the lower frequency range (<40Hz), and emphasized its higher (>40Hz), gamma range components. Further, our results show that CS increased the spectral correlation across multiple frequency bands in the low and high gamma ranges, and between the alpha and beta bands of the MEG. Finally, MEG sources localized in the auditory cortices and nearby regions exhibited abnormal spectral activity that was suppressed by CS. These results provide promising evidence in favor of the Thalamocortical Dysrhytmia (TCD) hypothesis of tinnitus, and suggest that CS may prove to be an effective treatment of tinnitus when targeted to brain regions exhibiting abnormal spontaneous activity.
Magnetoencephalography
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Magnetoencephalography
Beta Rhythm
Alpha (finance)
EEG-fMRI
BETA (programming language)
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The analysis of scale-free (i.e., 1/f power spectrum) brain activity has emerged in the last decade since it has been shown that low frequency fluctuations interact with oscillatory activity in electrophysiology, noticeably when exogenous factors (stimuli, task) are delivered to the human brain. However, there are some major difficulties in measuring scale-free activity in neuroimaging data: they are noisy, possibly nonstationary ... Here, we make use of multifractal analysis to better understand the biological meaning of scale-free activity recorded with Magnetoencephalography (MEG) data. On a cohort of 20 subjects, we demonstrate the presence of self-similarity on all sensors during rest and visually evoked activity. Also, we report significant multifractality on the norm of gradiometers. Finally, on the latter signals we show how self-similarity and multifractality are modulated between ongoing and evoked activity.
Magnetoencephalography
Multifractal system
Evoked activity
Premovement neuronal activity
Similarity (geometry)
Neurophysiology
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Both magnetoencephalography and stereo-electroencephalography are used in presurgical epilepsy assessment, with contrasting advantages and limitations. It is not known whether simultaneous stereo-electroencephalography-magnetoencephalography recording confers an advantage over both individual modalities, in particular whether magnetoencephalography can provide spatial context to epileptiform activity seen on stereo-electroencephalography. Twenty-four adult and paediatric patients who underwent stereo-electroencephalography study for pre-surgical evaluation of drug-resistant focal epilepsy, were recorded using simultaneous stereo-electroencephalography-magnetoencephalography, of which 14 had abnormal interictal activity during recording. The 14 patients were divided into two groups; those with detected superficial (n = 7) and deep (n = 7) brain interictal activity. Interictal spikes were independently identified in stereo-electroencephalography and magnetoencephalography. Magnetoencephalography dipoles were derived using a distributed inverse method. There was no significant difference between stereo-electroencephalography and magnetoencephalography in detecting superficial spikes (P = 0.135) and stereo-electroencephalography was significantly better at detecting deep spikes (P = 0.002). Mean distance across patients between stereo-electroencephalography channel with highest average spike amplitude and magnetoencephalography dipole was 20.7 ± 4.4 mm. for superficial sources, and 17.8 ± 3.7 mm. for deep sources, even though for some of the latter (n = 4) no magnetoencephalography spikes were detected and magnetoencephalography dipole was fitted to a stereo-electroencephalography interictal activity triggered average. Removal of magnetoencephalography dipole was associated with 1 year seizure freedom in 6/7 patients with superficial source, and 5/6 patients with deep source. Although stereo-electroencephalography has greater sensitivity in identifying interictal activity from deeper sources, a magnetoencephalography source can be localized using stereo-electroencephalography information, thereby providing useful whole brain context to stereo-electroencephalography and potential role in epilepsy surgery planning.
Magnetoencephalography
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