Publications by authors named "Nat Hemasilpin"

Objective evaluation of language function is critical for children with intractable epilepsy under consideration for epilepsy surgery. The purpose of this preliminary study was to evaluate word recognition in children with intractable epilepsy by using magnetoencephalography (MEG). Ten children with intractable epilepsy (M/F 6/4, mean ± SD 13.

View Article and Find Full Text PDF

Recent studies have revealed the importance of high-frequency brain signals (>70 Hz). One challenge of high-frequency signal analysis is that the size of time-frequency representation of high-frequency brain signals could be larger than 1 terabytes (TB), which is beyond the upper limits of a typical computer workstation's memory (<196 GB). The aim of the present study is to develop a new method to provide greater sensitivity in detecting high-frequency magnetoencephalography (MEG) signals in a single automated and versatile interface, rather than the more traditional, time-intensive visual inspection methods, which may take up to several days.

View Article and Find Full Text PDF

Purpose: Magnetoencephalography (MEG) has been shown a useful diagnostic tool for presurgical evaluation of pediatric medically intractable partial epilepsy as MEG source localization has been shown to improve the likelihood of seizure onset zone (SOZ) sampling during subsequent evaluation with intracranial EEG (ICEEG). We investigated whether ictal MEG onset source localization further improves results of interictal MEG in defining the SOZ.

Methods: We identified 20 pediatric patients with one habitual seizure during MEG recordings between October 2007 and April 2011.

View Article and Find Full Text PDF

Recent studies in adults have found consistent contralateral high gamma activities in the sensorimotor cortex during unilateral finger movement. However, no study has reported on this same phenomenon in children. We hypothesized that contralateral high gamma activities also exist in children during unilateral finger movement.

View Article and Find Full Text PDF

Object: Recent reports suggest that high-frequency epileptic activity is highly localized to epileptogenic zones. The goal of the present study was to investigate the potential usefulness of noninvasive localization of high-frequency epileptic activity for epilepsy surgery.

Methods: Data obtained in 4 patients, who had seizures during routine magnetoencephalography (MEG) tests, were retrospectively studied.

View Article and Find Full Text PDF

In recent years, there has been a growing interest on the role of gamma band (>30 Hz) neural oscillations in motor control, although the function of this activity in motor control is unknown clearly. With the goal of discussing the high frequency sources non-invasively and precisely during unilateral index finger movement, we investigated gamma band oscillations in 20 right-handed normal adults with magnetoencephalography (MEG). The results showed that gamma band activity appeared only during finger movement.

View Article and Find Full Text PDF

Purpose: Invasive intracranial recordings have suggested that high-frequency oscillation is involved in epileptogenesis and is highly localized to epileptogenic zones. The aim of the present study is to characterize the frequency and spatial patterns of high-frequency brain signals in childhood epilepsy using a non-invasive technology.

Methods: Thirty children with clinically diagnosed epilepsy were studied using a whole head magnetoencephalography (MEG) system.

View Article and Find Full Text PDF

Background: Magnetoencephalography (MEG) is increasingly used in the presurgical evaluation of pediatric seizure patients. Many pediatric patients require sedation or anesthesia to tolerate these exams. However, the available literature on anesthetic management in this population is very limited.

View Article and Find Full Text PDF

Recent studies have found that the brain generates very fast oscillations. The objective of the present study was to investigate the spectral, spatial and coherent features of high-frequency brain oscillations in the developing brain. Sixty healthy children and 20 healthy adults were studied using a 275-channel magnetoencephalography (MEG) system.

View Article and Find Full Text PDF

Hemispheric specialization or asymmetry in higher brain functions such as language is well accepted. This study was designed to quantitatively determine if the hemispheric asymmetry is measurable in the somatosensory system. Twenty-two participants were studied with magnetoencephalography (MEG) while their left and right index fingers were stimulated in randomized order.

View Article and Find Full Text PDF