Cortico-cortical modulation induced by 1-Hz repetitive transcranial magnetic stimulation of the temporal cortex.

Background And Purpose: Repetitive transcranial magnetic stimulation (rTMS) has potential as a noninvasive neuromodulation treatment method for various neuropsychiatric disorders, and repeated sessions of rTMS are more likely to enhance the therapeutic efficacy. This study investigated neurophysiologic and spatiodynamic changes induced by repeated 1-Hz rTMS of the temporal cortex using transcranial magnetic stimulation (TMS) indices and fluorodeoxyglucose positron emission tomography (FDG-PET).

Methods: Twenty-seven healthy subjects underwent daily 1-Hz active or sham rTMS of the right temporal cortex for 5 consecutive days.

Gamma phase locking modulated by phonological contrast during auditory comprehension in reading disability.

Children with specific reading impairment may have subtle deficits in speech perception related to difficulties in phonological processing. The aim of this study was to examine brain oscillatory activity related to phonological processing in the context of auditory sentence comprehension using magnetoencephalography to better understand these deficits. Good and poor readers, 16-18 years of age, were tested on speech perception of sentence-terminal incongruent words that were phonologically manipulated to be similar or dissimilar to corresponding congruent target words.

Sensitivity of MEG and EEG to source orientation.

An important difference between magnetoencephalography (MEG) and electroencephalography (EEG) is that MEG is insensitive to radially oriented sources. We quantified computationally the dependency of MEG and EEG on the source orientation using a forward model with realistic tissue boundaries. Similar to the simpler case of a spherical head model, in which MEG cannot see radial sources at all, for most cortical locations there was a source orientation to which MEG was insensitive.

Cancellation of EEG and MEG signals generated by extended and distributed sources.

Extracranial patterns of scalp potentials and magnetic fields, as measured with electro- and magnetoencephalography (EEG, MEG), are spatially widespread even when the underlying source in the brain is focal. Therefore, loss in signal magnitude due to cancellation is expected when multiple brain regions are simultaneously active. We characterized these cancellation effects in EEG and MEG using a forward model with sources constrained on an anatomically accurate reconstruction of the cortical surface.

Evaluation of smoothing in an iterative lp-norm minimization algorithm for surface-based source localization of MEG.

The imaging of neural sources of magnetoencephalographic data based on distributed source models requires additional constraints on the source distribution in order to overcome ill-posedness and obtain a plausible solution. The minimum l(p) norm (0 < p < or = 1) constraint is known to be appropriate for reconstructing focal sources distributed in several regions. A well-known recursive method for solving the l(p)-norm minimization problem, for example, is the focal underdetermined system solver (FOCUSS).

Regularized FOCUSS algorithm for EEG/MEG source imaging.

In this paper, we derived a generalized version of the regularized FOCUSS algorithm which was derived in [3]. It allows general forms of noise covariance and reduces depth effect when imaging focal neural sources from electroencephalography (EEG) / magnetoencephalography (MEG) data. We compared a depth-weighted regularized algorithm with FOCUSS and a regularized FOCUSS through simulation study.

Air mattress sensor system with balancing tube for unconstrained measurement of respiration and heart beat movements.

The cardio-respiratory signal is a fundamental vital sign used for assessment of a patient's status. Additionally, the cardio-respiratory signal provides a great deal of information to healthcare providers wishing to monitor healthy individuals. The air mattress sensor system allows the measurement of the respiration and heart beat movements without the use of a harness or sensor on the subject's body, which eliminates the difficulties these pose for long term measurements.