Synchronizing movements with rhythmic inputs requires tight coupling of sensory and motor neural processes. Here, using a novel approach based on the recording of steady-state-evoked potentials (SS-EPs), we examine how distant brain areas supporting these processes coordinate their dynamics. The electroencephalogram was recorded while subjects listened to a 2.4-Hz auditory beat and tapped their hand on every second beat. When subjects tapped to the beat, the EEG was characterized by a 2.4-Hz SS-EP compatible with beat-related entrainment and a 1.2-Hz SS-EP compatible with movement-related entrainment, based on the results of source analysis. Most importantly, when compared with passive listening of the beat, we found evidence suggesting an interaction between sensory- and motor-related activities when subjects tapped to the beat, in the form of (1) additional SS-EP appearing at 3.6 Hz, compatible with a nonlinear product of sensorimotor integration; (2) phase coupling of beat- and movement-related activities; and (3) selective enhancement of beat-related activities over the hemisphere contralateral to the tapping, suggesting a top-down effect of movement-related activities on auditory beat processing. Taken together, our results are compatible with the view that rhythmic sensorimotor synchronization is supported by a dynamic coupling of sensory and motor related activities.

The purpose of this study is to develop and quantitatively assess whether fusion of EEG and MEG (MEEG) data within the maximum entropy on the mean (MEM) framework increases the spatial accuracy of source localization, by yielding better recovery of the spatial extent and propagation pathway of the underlying generators of inter-ictal epileptic discharges (IEDs). The key element in this study is the integration of the complementary information from EEG and MEG data within the MEM framework. MEEG was compared with EEG and MEG when localizing single transient IEDs. The fusion approach was evaluated using realistic simulation models involving one or two spatially extended sources mimicking propagation patterns of IEDs. We also assessed the impact of the number of EEG electrodes required for an efficient EEG–MEG fusion. MEM was compared with minimum norm estimate, dynamic statistical parametric mapping, and standardized low-resolution electromagnetic tomography. The fusion approach was finally assessed on real epileptic data recorded from two patients showing IEDs simultaneously in EEG and MEG. Overall the localization of MEEG data using MEM provided better recovery of the source spatial extent, more sensitivity to the source depth and more accurate detection of the onset and propagation of IEDs than EEG or MEG alone. MEM was more accurate than the other methods. MEEG proved more robust than EEG and MEG for single IED localization in low signal-to-noise ratio conditions. We also showed that only few EEG electrodes are required to bring additional relevant information to MEG during MEM fusion. Electronic supplementary materialThe online version of this article (doi:10.1007/s10548-015-0437-3) contains supplementary material, which is available to authorized users.

In this review, authors discuss the semiology and noninvasive investigations of insular epilepsy, an underrecognized type of epilepsy, which may mimic other focal epilepsies. In line with the various functions of the insula and its widespread network of connections, insular epilepsy may feature a variety of early ictal manifestations from somatosensory, visceral, olfactory, gustatory, or vestibular manifestations. Depending on propagation pathways, insular seizures may also include altered consciousness, dystonic posturing, complex motor behaviors, and even autonomic features. Considering the variability in seizure semiology, recognition of insular epilepsy may be challenging and confirmation by noninvasive tests is warranted although few studies have assessed their value. Detection of an insular lesion on MRI greatly facilitates the diagnosis. Scalp EEG findings in frontocentral and/or temporal derivations will generally allow lateralization of the seizure focus. Ictal single-photon computed tomography has moderate sensitivity, whereas positron emission tomography has lower sensitivity. Among newer techniques, magnetoencephalography is highly beneficial, whereas proton magnetic resonance spectroscopy currently has limited value.