Результаты поиска

Different cortical dynamics in face and body perception: an MEG study.

Evidence from functional neuroimaging indicates that visual perception of human faces and bodies is carried out by distributed networks of face and body-sensitive areas in the occipito-temporal cortex. However, the dynamics of activity in these areas, needed to understand their respective functional roles, are still largely unknown. We monitored brain activity with millisecond time resolution by recording magnetoencephalographic (MEG) responses while participants viewed photographs of faces, bodies, and control stimuli. The cortical activity underlying the evoked responses was estimated with a

Visual cortex excitability and plasticity associated with remission from chronic to episodic migraine.

OBJECTIVE: Previous magnetoencephalographic (MEG) studies showed different P100m (where 'm' denotes the magnetic counterpart of P100 in conventional visual evoked potentials) responses between episodic migraine (EM) and chronic migraine (CM) interictally. This study investigated the changes of visual P100m in CM patients who remitted to EM from CM after treatment. METHODS: At baseline, 25 patients with CM were studied interictally. For each patient, 30 sequential blocks of 50 P100m responses were obtained by MEG. Sub-averaged amplitudes at blocks 2, 9, 16, 23 and 30 were further compared with

Dynamical MEG source modeling with multi-target Bayesian filtering.

We present a Bayesian filtering approach for automatic estimation of dynamical source models from magnetoencephalographic data. We apply multi-target Bayesian filtering and the theory of Random Finite Sets in an algorithm that recovers the life times, locations and strengths of a set of dipolar sources. The reconstructed dipoles are clustered in time and space to associate them with sources. We applied this new method to synthetic data sets and show here that it is able to automatically estimate the source structure in most cases more accurately than either traditional multi-dipole modeling or

Residual cerebral activity and behavioural fragments can remain in the persistently vegetative brain.

This report identifies evidence of partially functional cerebral regions in catastrophically injured brains. To study five patients in a persistent vegetative state (PVS) with different behavioural features, we employed [(18)F]fluorodeoxyglucose-positron emission tomography (FDG-PET), MRI and magnetoencephalographic (MEG) responses to sensory stimulation. Each patient's brain expressed a unique metabolic pattern. In three of the five patients, co-registered PET/MRI correlate islands of relatively preserved brain metabolism with isolated fragments of behaviour. Two patients had suffered anoxic

Normal movement reading in Asperger subjects.

Patients with autism and Asperger syndrome (AS) are impaired in mindreading and imitation skills. One possibility would be that their 'mirror neuron' system, which matches action execution and observation, does not function properly. To test this hypothesis we compared action-viewing related motor cortex functions in an AS group (one autistic and four AS subjects) and eight control subjects. In both groups viewing hand actions modified the neuromagnetic approximately 20 Hz oscillatory activity in the primary motor cortex to the same extent. Thus impaired mindreading and imitation skills found

Words without mind.

A woman (LR), unconscious for 20 years, spontaneously produces infrequent, isolated words unrelated to any environmental context. Fluorodeoxy-glucose-positron emission tomography (FDG-PET) imaging coregistered with magnetic resonance imaging (MRI) revealed a mean brain metabolism equivalent to deep anesthesia. Nevertheless, PET imaging demonstrated islands of modestly higher metabolism that included Broca's and Wernicke's areas. Functional brain imaging with magnetoencephalographic (MEG) imaging, a technique providing a temporal resolution of better than 1 msec, identified preserved dynamic pa

[Locating the central sulcus using three dimensional image fusion system of helmet shaped whole head MEG and MRI].

We compared MR anatomy and magnetoencephalographic (MEG) functional methods in locating the central sulcus. In 20 normal volunteers and 58 patients with intracranial structural lesions, the short latency somatosensory evoked magnetic fields for median nerve and posterior tibial nerve stimuli were measured over the entire head, using a helmet shaped MEG system. The dipole positions estimated by a single current dipole model were projected onto the three dimensional MRI. In 94% of a total of 156 hemispheres, N20m dipole positions for median nerve stimuli coincided with the central sulcus defined

Картирование мозжечного мозга в случае задержек с проведением: следующий шаг для личностных моделей мозга в многоразовом склерозе.

Множественный склероз (MS) — клинически неоднородное, многофакторное аутоиммунное расстройство, затрагивающее центральную нервную систему. Структурные повреждения миелинской оболочки, приводящие к замедлению скорости проведения, являются ключевым патофизиологическим механизмом. На самом деле, скорость проведения тесно связана с степенью миэлизации, при этом более толстые миелиновые оболочки связаны с более высокой скоростью проведения. Однако не известно, как интенсивность структурных повреждений миелина ведет к замедлению течения нервной системы. В этой работе мы используем крупномасштабные м

Совпадение в полном тексте источника
… To overcome this difficulty, (Sorrentino et al.  2023 ) opted to infer patient‐specific average conduction velocities by integrating diffusion tensor imaging and source‐reconstructed magnetoencephalography (MEG) data into a personalized large‐scale brain model. …

Detrended fluctuation analysis in the presurgical evaluation of parietal lobe epilepsy patients.

OBJECTIVE: To examine the usability of long-range temporal correlations (LRTCs) in non-invasive localization of the epileptogenic zone (EZ) in refractory parietal lobe epilepsy (RPLE) patients. METHODS: We analyzed 10 RPLE patients who had presurgical MEG and underwent epilepsy surgery. We quantified LRTCs with detrended fluctuation analysis (DFA) at four frequency bands for 200 cortical regions estimated using individual source models. We correlated individually the DFA maps to the distance from the resection area and from cortical locations of interictal epileptiform discharges (IEDs). Addi

Spectral and Anatomical Patterns of Large-Scale Synchronization Predict Human Attentional Capacity.

The capacity of visual attention determines how many visual objects may be perceived at any moment. This capacity can be investigated with multiple object tracking (MOT) tasks, which have shown that it varies greatly between individuals. The neuronal mechanisms underlying capacity limits have remained poorly understood. Phase synchronization of cortical oscillations coordinates neuronal communication within the fronto-parietal attention network and between the visual regions during endogenous visual attention. We tested a hypothesis that attentional capacity is predicted by the strength of pre

[Pathophysiology of tremor].

Tremor is clinically defined as a rhythmic, oscillating movement of parts of the body, which functionally leads to impairment of the coordination and execution of targeted movements. It can be a symptom of a primary disease, such as resting tremor in Parkinson's disease or occur as an independent disease, such as essential or orthostatic tremor. For the development of tremor, cerebral components as well as mechanisms at the spinal and muscular level play an important role. This review presents the results of new imaging and electrophysiological studies that have led to important advances in ou

MEG-compatible pneumatic stimulator to elicit passive finger and toe movements.

Magnetoencephalographic (MEG) signals recorded from the primary sensorimotor (SM1) cortex are coherent with kinematics of both active and passive finger movements. The coherence mainly reflects movement-related proprioceptive afference to the cortex. Here we describe a novel MEG-compatible stimulator to generate computer-controlled passive finger and toe movements that can be used as stimuli in functional brain-imaging experiments. The movements are produced by pneumatic artificial muscle (PAM), elastic actuator that shortens with increasing air pressure. To test the applicability of the stimu

Late-onset epilepsy in children with acute febrile encephalopathy with prolonged convulsions: A clinical and encephalographic study.

The aim of this study is to analyze the characteristics of epilepsies as the sequelae of acute febrile encephalopathy with prolonged convulsions during childhood. Sixteen patients (M:F=9:7) aged 2-13years (mean 6.1years) with history of febrile acute encephalopathy were retrospectively reviewed. These patients experienced febrile encephalopathy at the age of 11months to 4years, with 11 individuals presenting with findings of a biphasic clinical course (n=5), frontal predominant (n=8) lesions, and/or reduced diffusivity in the cerebral white matter on magnetic resonance imaging (MRI; n=3). The

Periventricular leukomalacia specifically affects cortical MEG response to biological motion.

OBJECTIVE: Periventricular leukomalacia (PVL) underlies most of the neurological morbidity including visual-perceptual deficits in survivors of premature birth. However, it is unknown whether and, if so, how PVL affects functional cortical activity. METHODS: Here, we assessed changes in the magnetoencephalographic (MEG) response to visual displays depicting human locomotion in adolescents who were born premature with magnetic resonance imaging signs of PVL. RESULTS: Dynamics of MEG activity parallel behavioral deficits. Early (140-170 milliseconds) brain activation over the right parietal co

Reduced hemispheric asymmetry of the auditory N260m in dyslexia.

Dyslexia seems to be related to a lack of planum temporale (PT) asymmetry that is accompanied by functional differences to control subjects in both left and right hemispheric temporal regions during language tasks. PT asymmetry has been found to correlate with phonological and verbal skills. In accordance, reduced asymmetry of the auditory N100m sources in dyslexic adults and P100m sources in dyslexic children has been reported. These results might also be related to an atypical PT symmetry or the recruitment of other structures than the PT for speech processing in dyslexia. In the present stu

Early development of neurophysiological processes involved in normal reading and reading disability: a magnetic source imaging study.

This longitudinal study examined the development of the brain mechanism involved in phonological decoding in beginning readers using magnetic source imaging. Kindergarten students were assigned to 2 groups: those who showed mastery of skills that are important predictors of proficient reading (low-risk group) and those who initially did not show mastery but later benefited from systematic reading instruction and developed average-range reading skills at the end of Grade 1 (high-risk responders). Spatiotemporal profiles of brain activity were obtained during performance of letter-sound and pseu

Displacement of central sulcus in cerebral arteriovenous malformation situated in the peri-motor cortex as assessed by magnetoencephalographic study.

BACKGROUND: Intra-operative monitoring of the position of the central sulcus (CS) is indispensable to properly treat a peri-motor cortex lesion. Noninvasive preoperative studies for identification of CS are also needed for choosing the optimal operative procedure. Magneto-encephalography (MEG) has recently been introduced for non-invasive preoperative investigation and cortical functional mapping. METHODS: Stereotactic mapping of functional CS anatomy was performed preoperatively on 13 subjects using somatosensory evoked fields with MRI-linked whole head MEG system. All subjects had a left si

Diminished auditory mismatch fields in dyslexic adults.

Electroencephalographic studies have demonstrated smaller auditory responses to infrequent deviances of speech and nonspeech sounds in dyslexic than normal-reading subjects. We used a whole-scalp neuromagnetometer to study selectively reactivity of the auditory cortices to sound deviances in 8 dyslexic and 11 normal-reading adults. Within a monotonous sequence of 50-millisecond 1000 Hz binaural tones, tones of 920 and 1080 Hz occurred with 7% probability each. Magnetic mismatch fields, elicited by the stimulus deviances, were diminished in the left hemisphere of the dyslexic subjects. The resu

Source localization of the re-build up phenomenon in pediatric moyamoya disease-a dipole distribution analysis using MEG and SPECT.

OBJECTS: The "re-build up" phenomenon is a pathognomonic finding induced after hyperventilation in pediatric moyamoya disease, and is closely related to ischemic attacks. However, its precise mechanism remains unknown. METHODS: In this study, MEG, MRI, and SPECT were used to clarify its mechanism in 4 children with moyamoya disease. Cerebral blood flow before and after acetazolamide administration was measured. Spontaneous magnetic brain activity was measured using a whole-head MEG system. The quantified dipole distribution was shown on 3D-MRI. RESULTS AND CONCLUSION: The original current di

Cortical reactivity in progressive myoclonus epilepsy.

We studied 4 patients with progressive myoclonus epilepsy (Unverricht-Lundborg disease; ULD). Somatosensory evoked fields (SEFs), auditory evoked fields (AEFs), and spontaneous activity over the somatomotor cortex were recorded with a 24-channel SQUID gradiometer. All patients had "giant" 20-45 msec median nerve SEFs at the first somatomotor cortex, with 2-6 times larger amplitudes than the healthy control subjects. Later deflections were not similarly enhanced. The dependence of SEF amplitudes on interstimulus interval (0.2-4 sec) and on successive ulnar-median nerve stimulation (stimulus int