Search results for "CORTEX"
showing 10 items of 1827 documents
Functional MRI of galvanic vestibular stimulation with alternating currents at different frequencies.
2004
Abstract Functional MRI was performed in 28 healthy volunteers to study the effects of galvanic vestibular stimulation with alternating currents (AC-GVS) of different frequencies on brain activation patterns. The aims of this study were (1) to identify specific areas within the vestibular cortical network that are involved in the processing of frequency-specific aspects by correlation analyses, (2) to determine the optimal frequency for stimulation of the vestibular system with respect to perception, and (3) to analyze whether different frequencies of AC-GVS are mediated in different cortical areas or different sites within the vestibular cortex. AC-GVS was performed using sinusoidal stimul…
The thalamus as the generator and modulator of EEG alpha rhythm: a combined PET/EEG study with lorazepam challenge in humans
2003
Background: Purpose of this study was to investigate the functional relationship between electroencephalographic (EEG) alpha power and cerebral glucose metabolism before and after pharmacological alpha suppression by lorazepam. Methods: Ten healthy male volunteers were examined undergoing two F18-fluorodeoxyglucose (18-FDG) positron emission tomography (PET) scans with simultaneous EEG recording: 1× placebo, 1× lorazepam. EEG power spectra were computed by means of Fourier analysis. The PET data were analyzed using SPM99, and the correlations between metabolism and alpha power were calculated for both conditions. Results: The comparison lorazepam versus placebo revealed reduced glucose meta…
Cortical representation of saccular vestibular stimulation: VEMPs in fMRI
2006
Short tone bursts trigger a vestibular evoked myogenic potential (VEMP), an inhibitory potential which reflects a component of the vestibulocollic reflex (VCR). These potentials arise as a result of activation of the sacculus and are expressed through the vestibulo-collic reflex (VCR). Up to now, the ascending projections of the sacculus are unknown in humans, only the representation of the semicircular canals or the entire vestibular nerve has been demonstrated. The aim of this study was to determine whether a sacculus stimulus that evoked VEMPs could activate vestibular cortical areas in fMRI. To determine this, we studied the differential effects of unilateral VEMP stimulation in 21 heal…
Modulating phonemic fluency performance in healthy subjects with transcranial magnetic stimulation over the left or right lateral frontal cortex.
2017
Abstract A growing body of evidence have suggested that non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), can improve the performance of aphasic patients in language tasks. For example, application of inhibitory rTMS or tDCs over the right frontal lobe of dysphasic patients resulted in improved naming abilities. Several studies have also reported that in healthy controls (HC) tDCS application over the left prefrontal cortex (PFC) improve performance in naming and semantic fluency tasks. The aim of this study was to investigate in HC, for the first time, the effects of inhibitory repetitive TMS (rTMS…
The Bandwidth of VWM Consolidation Varies With the Stimulus Feature: Evidence From Event-Related Potentials
2018
Our previous work suggests that 2 colors can be consolidated into visual short-term memory (VSTM) in parallel without a loss of memory precision, whereas consolidation of 2 orientations is performed in a strictly serial manner. Those experiments compared VSTM performance for simultaneously and sequentially presented stimuli. However, there is still controversy about whether the bandwidth for consolidation is determined by the type of information. To further investigate this issue, here we measured electroencephalography while participants attempted to consolidate 1, 2 or 4 simultaneously presented colors (Experiment 1) or orientations (Experiment 2) under limited presentation times. We used…
Relationship between dopamine D2 receptor occupancy, clinical response, and drug and monoamine metabolites levels in plasma and cerebrospinal fluid. …
2009
Combining measurements of the monoamine metabolites in the cerebrospinal fluid (CSF) and neuroimaging can increase efficiency of drug discovery for treatment of brain disorders. To address this question, we examined five drug-naive patients suffering from schizophrenic disorder. Patients were assessed clinically, using the Positive and Negative Syndrome Scale (PANSS): at baseline and then at weekly intervals. Plasma and CSF levels of quetiapine and norquetiapine as well CSF 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxyindole-acetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were obtained at baseline and again after at least a 4 week medication trai…
Is somatosensory amplification a risk factor for an increased report of side effects? Reference data from the German general population
2015
Abstract Objective The study investigates the association between somatosensory amplification and the reporting of side effects. It establishes a German version of the Somatosensory Amplification Scale and examines its psychometric properties in a representative sample of the German population. Methods Sample size was 2.469, with 51% taking any medication. Participants answered the Somatosensory Amplification Scale, Generic Assessment of Side Effects Scale, and indicated whether they were taking any medication and the type of medication. Correlational analysis and binary logistic regression were performed. Results When examining a subsample reporting both medication intake and general bodil…
Neural correlates of an attentional bias to health-threatening stimuli in individuals with pathological health anxiety
2017
Background: An attentional bias to health-threat stimuli is assumed to represent the primary pathogenetic factor for the development and maintenance of pathological health anxiety (PHA; formerly termed “hypochondriasis”). However, little is known about the neural basis of this attentional bias in individuals with PHA.Methods: A group of patients with PHA, a group of depressed patients and a healthy control group completed an emotional Stroop task with health-threat (body symptom and illness) words and neutral control words while undergoing functional MRI.Results: We included 33 patients with PHA, 28 depressed patients and 31 controls in our analyses. As reflected in reaction times, patients…
Perceptual Pseudoneglect in Schizophrenia: Candidate Endophenotype and the Role of the Right Parietal Cortex
2013
Several contributions have reported an altered expression of pseudoneglect in psychiatric disorders, highlighting the existence of an anomalous brain lateralization in affected subjects. Surprisingly, no studies have yet investigated pseudoneglect in first-degree relatives (FdR) of psychiatric patients. We investigated performance on “paper and pencil” line bisection (LB) tasks in 68 schizophrenic patients (SCZ), 42 unaffected FdR, 41 unipolar depressive patients (UP), and 103 healthy subjects (HS). A subgroup of 20 SCZ and 16 HS underwent computerized LB and mental number line bisection (MNL) tasks requiring judgment of prebisected lines and numerical intervals. Moreover, we evaluated, in …
Automatic Evaluation of Histological Prognostic Factors Using Two Consecutive Convolutional Neural Networks on Kidney Samples
2022
BACKGROUND AND OBJECTIVES: The prognosis of patients undergoing kidney tumor resection or kidney donation is linked to many histologic criteria. These criteria notably include glomerular density, glomerular volume, vascular luminal stenosis, and severity of interstitial fibrosis/tubular atrophy. Automated measurements through a deep-learning approach could save time and provide more precise data. This work aimed to develop a free tool to automatically obtain kidney histologic prognostic features. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In total, 241 samples of healthy kidney tissue were split into three independent cohorts. The “Training” cohort (n=65) was used to train two convoluti…