GABAergic inhibition shapes behavior and neural dynamics in human visual working memory.

Neuronal inhibition, primarily mediated by GABAergic neurotransmission, is crucial for brain development and healthy cognition. Gamma-aminobutyric acid concentration levels in sensory areas have been shown to correlate with hemodynamic and oscillatory neuronal responses. How these measures relate to one another during working memory, a higher-order cognitive process, is still poorly understood.

Subject-Specific Activation of Central Respiratory Centers during Breath-Holding Functional Magnetic Resonance Imaging.

Background: Voluntary breath-holding (BH) triggers responses from central neural control and respiratory centers in order to restore breathing. Such responses can be observed using functional MRI (fMRI).

Objectives: We used this paradigm in healthy volunteers with the view to develop a biomarker that could be used to investigate disorders of the central control of breathing at the individual patient level.

fMRI studies evaluating central respiratory control in humans.

A plethora of neural centers in the central nervous system control the fundamental respiratory pattern. This control is ensured by neurons that act as pacemakers, modulating activity through chemical control driven by changes in the O/CO balance. Most of the respiratory neural centers are located in the brainstem, but difficult to localize on magnetic resonance imaging (MRI) due to their small size, lack of visually-detectable borders with neighboring areas, and significant physiological noise hampering detection of its activity with functional MRI (fMRI).

Neural correlates of verbal working memory in children with epilepsy with centro-temporal spikes.

Background: Previous functional magnetic resonance imaging (fMRI) studies have identified brain systems underlying different components of working memory (WM) in healthy subjects. The aim of this study was to compare the functional integrity of these neural networks in children with self-limited childhood epilepsy with centro-temporal spikes (ECTS) as compared to healthy controls, using a verbal working memory task (WMT).

Methods: Functional MRI of WM in seventeen 6-to-13 year-old children, diagnosed with ECTS, and 17 sex- and age-matched healthy controls were conducted at 3 T.

Social cognition, behaviour and therapy adherence in frontal lobe epilepsy: a study combining neuroeconomic and neuropsychological methods.

Social behaviour of healthy humans and its neural correlates have been extensively studied in social neuroscience and neuroeconomics. Whereas it is well established that several types of epilepsies, such as frontal lobe epilepsy, lead to social cognitive impairments, experimental evidence on how these translate into behavioural symptoms is scarce. Furthermore, it is unclear whether social cognitive or behavioural disturbances have an impact on therapy adherence, which is critical for effective disease management, but generally low in these patients.

Limited evidence of physical therapy on balance after stroke: A systematic review and meta-analysis.

Background: Stroke results in balance disorders and these directly affect autonomy and quality of life. The purpose of this systematic review and meta-analysis was to determine the efficacy of physical therapy (PT) on balance and postural control after stroke.

Methods: We included all randomized controlled trials assessing the efficacy of PT on balance and postural control in adult patients after stroke without language restriction.

Wearable devices for sudden unexpected death in epilepsy prevention.

Sudden unexpected death in epilepsy (SUDEP) is most often associated with the occurrence of generalized tonic-clonic seizures (GTCS), a seizure type that can now be detected with high sensitivity and specificity by wearable or bed devices. The recent development in such devices and their performance offer multiple opportunities to tackle SUDEP and its prevention. Reliable GTCS detection might help physicians optimize antiepileptic treatment, which could in turn reduce the risk of SUDEP.

Behavioral and fMRI responses to fearful faces are altered in benign childhood epilepsy with centrotemporal spikes (BCECTS).

Objective: We hypothesized that children with benign childhood epilepsy with centrotemporal spikes (BCECTS) might have altered social cognitive skills and underlying neural networks.

Methods: We studied 13 patients with BCECTS and 11 age-matched controls using event-related functional magnetic resonance imaging (fMRI) with an emotional discrimination task consisting of viewing happy, fearful, scrambled, and neutral faces. Behavioral performance measured during the task was correlated with clinical variables and behavioral ratings.

Neural Activity Elicited by a Cognitive Task can be Detected in Single-Trials with Simultaneous Intracerebral EEG-fMRI Recordings.

Recent studies have shown that it is feasible to record simultaneously intracerebral EEG (icEEG) and functional magnetic resonance imaging (fMRI) in patients with epilepsy. While it has mainly been used to explore the hemodynamic changes associated with epileptic spikes, this approach could also provide new insight into human cognition. However, the first step is to ensure that cognitive EEG components, that have lower amplitudes than epileptic spikes, can be appropriately detected under fMRI.

Gamma oscillations in V1 are correlated with GABA(A) receptor density: A multi-modal MEG and Flumazenil-PET study.

High-frequency oscillations in the gamma-band reflect rhythmic synchronization of spike timing in active neural networks. The modulation of gamma oscillations is a widely established mechanism in a variety of neurobiological processes, yet its neurochemical basis is not fully understood. Modeling, in-vitro and in-vivo animal studies suggest that gamma oscillation properties depend on GABAergic inhibition.

White matter development in children with benign childhood epilepsy with centro-temporal spikes.

Benign childhood epilepsy with centro-temporal spikes (BCECTS) is a unique form of non-lesional age-dependent epilepsy with rare seizures, focal electroencepalographic abnormalities affecting the same well delineated cortical region in most patients, and frequent mild to moderate cognitive dysfunctions. In this condition, it is hypothesized that interictal electroencepalographic discharges might interfere with local brain maturation, resulting in altered cognition. Diffusion tensor imaging allows testing of this hypothesis by investigating the white matter microstructure, and has previously proved sensitive to epilepsy-related alterations of fractional anisotropy and diffusivity.

A phantom and animal study of temperature changes during fMRI with intracerebral depth electrodes.

Background: MRI is routinely used in patients undergoing intracerebral electroencephalography (icEEG) in order to precisely locate the position of intracerebral electrodes. In contrast, fMRI has been considered unsafe due to suspected greater risk of radiofrequency-induced (RF) tissue heating at the vicinity of intracerebral electrodes. We determined the possible temperature change at the tip of such electrodes during fMRI sessions in phantom and animals.

Effects of aripiprazole, risperidone, and olanzapine on 5-HT1A receptors in patients with schizophrenia.

To investigate the impact of various antipsychotic drugs on the 5-HT1A serotoninergic system, we performed a [F]4-(2-methoxyphenyl)-1-[2-(N-2-pirydynyl)-p-luorobenzamido]-ethyl-piperazine PET study in 19 schizophrenic patients treated with either aripiprazole, which has a partial agonist activity at 5-HT1A receptors, or second-generation antipsychotics (SGA) (olanzapine or risperidone), which do not demonstrate such property. We used a simplified reference tissue model to generate parametric images of [F]MPPF-binding potential (BPND). A significant reduction of [F]MPPF BPND was found in treated schizophrenic patients compared to age- and sex-matched healthy subjects.

Disengagement and inhibition of visual-spatial attention are differently impaired in children with rolandic epilepsy and Panayiotopoulos syndrome.

We assessed voluntary orientation and reorientation of visuospatial attention in 313 healthy 6- to 22-year-old participants, 30 children suffering from benign epilepsy with centrotemporal spikes (BECTS) and 13 children with Panayiotopoulos syndrome (PS). The developmental section highlights the late development of reorienting skills. Only children with BECTS-R showed a strong tendency toward a rightward bias in attentional orientation.

Efficient "pop-out" visual search elicits sustained broadband γ activity in the dorsal attention network.

An object that differs markedly from its surrounding-for example, a red cherry among green leaves-seems to pop out effortlessly in our visual experience. The rapid detection of salient targets, independently of the number of other items in the scene, is thought to be mediated by efficient search brain mechanisms. It is not clear, however, whether efficient search is actually an "effortless" bottom-up process or whether it also involves regions of the prefrontal cortex generally associated with top-down sustained attention.

Quantitative PET analyses of regional [11C]PE2I binding to the dopamine transporter--application to juvenile myoclonic epilepsy.

The dopamine transporter (DAT) is of central interest in research on the pathophysiology and treatment of neuro-psychiatric disorders. [(11)C]PE2I is an established radioligand that provides high-contrast delineation of brain regions that are rich in DAT. The aim of the present PET study in eight patients with juvenile myoclonic epilepsy (JME) was to evaluate the kinetics of [(11)C]PE2I in the brain and to compare binding parameters with those of age-matched control subjects (n = 6).

The dopamine system in idiopathic generalized epilepsies: identification of syndrome-related changes.

The present study tests the hypothesis that the dopamine system is altered in idiopathic generalized epilepsy (IGE), and that the pattern of possible changes differs between juvenile myoclonic epilepsy (JME) and epilepsy with tonic-clonic seizures only (GTCS). The dopamine (DA) system was investigated with PET and a DA transporter (DAT) ligand [(11)C]PE2I in 13 patients with JME, 13 with GTCS, and 12 healthy controls. The binding potential (BP) to DAT was quantified in the caudate, putamen, and midbrain.

High fetal testosterone and sexually dimorphic cerebral networks in females.

Active masculinization by fetal testosterone is believed to be a major factor behind sex differentiation of the brain. We tested this hypothesis in a 15O-H2O positron emission tomography study of 11 women with congenital adrenal hyperplasia (CAH), a condition with high fetal testosterone, and 26 controls. Two indices of cerebral dimorphism were measured--functional connectivity and cerebral activation by 2 putative pheromones (androstadienone [AND] and estratetraenol [EST]), previously reported to activate the hypothalamic networks in a sex-differentiated manner.

Magnetic resonance imaging in clinical trials.

Purpose Of Review: The aim of this article is to review the latest clinical trials in neurological diseases where magnetic resonance imaging was used to assess treatment outcome.

Recent Findings: The unique sensitivity of magnetic resonance imaging for detecting disorders in the brain has made it an attractive noninvasive tool for assessing treatment efficacy in several diseases. Volumetric and functional magnetic resonance imaging have proved to represent robust biomarkers for the evaluation of anti-Alzheimer treatments, and have demonstrated a significant impact of cholinesterase inhibitors.

Reduced dopamine transporter binding in patients with juvenile myoclonic epilepsy.

Background: Behavioral and cognitive problems are frequently encountered in juvenile myoclonic epilepsy (JME). The underlying mechanisms are unknown. Based on previous data showing that the dopamine system is involved in motor as well as cognitive functions, we tested whether JME may be associated with changes in this system, and if such changes are linked to interictal dysfunctions in these patients.

Imaging of odor perception delineates functional disintegration of the limbic circuits in mesial temporal lobe epilepsy.

Metabolic and neuro-receptor abnormalities within the extrafocal limbic circuits are established in mesial temporal lobe epilepsy (MTLE). However, very little is known about how these circuits process external stimuli. We tested whether odor activation can help delineate limbic functional disintegration in MTLE, and measured cerebral blood flow with PET during birhinal smelling of familiar and unfamiliar odors, using smelling of odorless air as the baseline condition.

Structural changes in patients with primary generalized tonic and clonic seizures.

We conducted MR volumetry and voxel-based morphometry in 19 patients who had idiopathic generalized epilepsy (IGE) with tonic clonic seizures as the only seizure type and 52 control subjects. Patients exhibited elevated frontal lobe fraction of CSF and reduced fraction of gray matter in the frontal, parietal, temporal cortex, thalamus, and cerebellum. The thalamus and cerebellum also showed reduced volumes, as did the caudate and putamen.

Odor processing in multiple chemical sensitivity.

Multiple chemical sensitivity (MCS) is characterized by somatic distress upon exposure to odors. As in other idiopathic environmental intolerances, the mechanisms behind the reported hypersensitivity are unknown. Using the advantage of the well-defined trigger (odor), we investigated whether subjects with MCS could have an increased odor-signal response in the odor-processing neuronal circuits.

Increased thalamus levels of glutamate and glutamine (Glx) in patients with idiopathic generalised epilepsy.

Objective: Abnormal thalamo-cortical oscillations underlie idiopathic generalised epilepsy (IGE). Although thalamic involvement has long been indicated by electrophysiological data, it has only recently become feasible to test this with independent methods. In this magnetic resonance (MR) study, we investigated the metabolic and structural integrity of the thalamus.

Autoantigen-pulsed dendritic cells constitute a beneficial cytokine and growth factor network in ameliorating experimental allergic encephalomyelitis.

Injection of myelin basic protein (MBP)-pulsed dendritic cells (DC) into healthy rats, as we reported before and observed in this study, did not induce clinical experimental allergic encephalomyelitis (EAE), but effectively protected the rats from subsequent EAE induction. The mechanisms by which MBP-pulsed DC mediate immune protection are not completely understood. In the present study, we mainly explored the dynamic change of cytokine and growth factor mRNA expression in spinal cords after subcutaneous injection of MBP-pulsed and unpulsed DC.