When multiple persons speak simultaneously, it may be difficult for the listener to direct attention to correct sound objects among conflicting ones. This could occur, for example, in an emergency situation in which one hears conflicting instructions and the loudest, instead of the wisest, voice prevails. Here, we used cortically-constrained oscillatory MEG/EEG estimates to examine how different brain regions, including caudal anterior cingulate (cACC) and dorsolateral prefrontal cortices (DLPFC), work together to resolve these kinds of auditory conflicts.
Alpha band power, particularly at the 10 Hz frequency, is significantly involved in sensory inhibition, attention modulation, and working memory. However, the interactions between cortical areas and their relationship to the different functional roles of the alpha band oscillations are still poorly understood. Here we examined alpha band power and the cortico-cortical interregional phase synchrony in a psychophysical task involving the detection of an object moving in depth by an observer in forward self-motion.
The ability to inhibit prepotent responses is critical for successful goal-directed behaviors. To investigate the neural basis of inhibitory control, we conducted a magnetoencephalography study where human participants performed the antisaccade task. Results indicated that neural oscillations in the prefrontal cortex (PFC) showed significant task modulations in preparation to suppress saccades. Before successfully inhibiting a saccade, beta-band power (18-38 Hz) in the lateral PFC and alpha-band power (10-18 Hz) in the frontal eye field (FEF) increased.
Detection of lactate by in vivo 1H magnetic resonance spectroscopy may provide a means of identifying regions of metabolic stress in brain and other human tissue, potentially identifying regional ischemia in stroke or necrosis in tumors. At higher field strengths (3 and 4 T), which have recently become available for whole-body human studies, the chemical shift difference between the doublet from the methyl protons and the quartet from the methine proton becomes comparable to the available radiofrequency (RF) pulse bandwidth.
Oscillatory brain activity is attracting increasing interest in cognitive neuroscience. Numerous EEG (magnetoencephalography) and local field potential (LFP) measurements have related cognitive functions to different types of brain oscillations, but the functional significance of these rhythms remains poorly understood. Despite its proven value, LFP activity has not been extensively tested in the macaque lateral intraparietal area (LIP), which has been implicated in a wide variety of cognitive control processes.
To assess the clinical value of magnetoencephalography (MEG) in investigating the origin of secondary bilateral synchrony (SBS) in patients with partial epilepsy. MEG and simultaneous electroencephalography (EEG) were recorded with a 204-channel whole-head MEG system in 2 patients. The equivalent current dipoles (ECDs) for epileptic discharges on MEG were calculated according to a single dipole model. In patient 1, the ictal EEG showed bursts of bilateral synchronous 3-Hz spike-and-slow-wave complexes. ECDs obtained from the ictal MEG localized to the right medial frontal lobe.
PURPOSE: To determine the electromagnetic sources of localized epileptic activities using magnetoencephalography (MEG) in three adult patients with epilepsy suggestive of Lennox-Gastaut syndrome (LGS).
METHODS: MEG and simultaneous electroencephalography (EEG) were recorded from three adult patients using a 204-channel, whole-head MEG system. Equivalent current dipoles (ECDs) were calculated for epileptic spikes on MEG according to the single dipole model.
Recent investigations have demonstrated that temporal patterns of sensory neural activity detected by magnetoencephalography (MEG) reflect features of the stimulus. In this study, neuromagnetic activity was investigated using an event detection algorithm based on the correlation coefficient. The results of the technique are compared with widely used methods of analysis in two experimental conditions and are shown to identify features in the single-trial MEG response that are not apparent in the response obtained by averaging across repeated trials.
