Search results for "Cortex"
showing 10 items of 1827 documents
Motor Action Execution in Reaction-Time Movements
2019
OBJECTIVE Reaction-time movements are internally planned in the brain. Presumably, proactive control in reaction-time movements appears as an inhibitory phase preceding movement execution. We identified the brain activity of reaction-time movements in close proximity to movement onset and compared it with similar self-paced voluntary movements without external command. DESIGN We recorded 18 healthy participants performing reaction-time and self-paced fast index finger abductions with 306-sensor magnetoencephalography and electromyography. Reaction-time movements were performed as responses to cutaneous electrical stimulation delivered on the hand radial nerve area. Motor field and movement-…
Disturbed brain activation during a working memory task in drug-naive adult patients with ADHD.
2010
Neuroimaging studies in attention-deficit/hyperactivity disorder (ADHD) have shown abnormalities in several brain areas including the frontostriatal circuitry and were mostly conducted in children and adolescents. We investigated 30 never-medicated adult ADHD patients (16 males) and 30 matched healthy control individuals. Functional magnetic resonance imaging was acquired during a working memory paradigm (n-back). Group activation maps and group differences of activation were calculated using voxel-based analyses. The generic activation pattern was more extended in the control group. In ADHD patients, significantly decreased activation was found in the right inferior parietal cortex. Distur…
Interhemispheric cooperation for face recognition but not for affective facial expressions
2003
Abstract Interhemispheric cooperation can be indicated by enhanced performance when stimuli are presented to both visual fields relative to one visual field alone. This “bilateral gain” is seen for words but not pseudowords in lexical decision tasks, and has been attributed to the operation of interhemispheric cell assemblies that exist only for meaningful words with acquired cortical representations. Recently, a bilateral gain has been reported for famous but not unfamiliar faces in a face recognition task [Neuropsychologia 40 (2002) 1841]. In Experiment 1 of the present paper, participants performed familiarity decisions for faces that were presented to the left (LVF), the right (RVF), or…
Event-Related Potentials and Autonomic Responses to a Change in Unattended Auditory Stimuli
1992
Event-related brain potentials (ERPs) and autonomic nervous system (ANS) responses to occasional pitch and rise-time changes in a task-irrelevant auditory stimulus repeating at short intervals were measured while the subject performed a difficult intellectual task (Raven Matrices). It was found that deviant stimuli elicited the mismatch negativity (MMN) component of the ERP even when they elicited no ANS response. There was no significant difference in the mismatch negativity between trials in which the skin conductance response was or was not elicited. The pitch deviant tone also elicited heart rate deceleration, whereas the rise-time deviant tone tended to elicit a later heart rate accele…
Linking planning performance and gray matter density in mid-dorsolateral prefrontal cortex: Moderating effects of age and sex
2012
Abstract Planning of behavior relies on the integrity of the mid-dorsolateral prefrontal cortex (mid-dlPFC). Yet, only indirect evidence exists on the association of protracted maturation of dlPFC and continuing gains in planning performance post adolescence. Here, gray matter density of mid-dlPFC in young, healthy adults (18–32 years) was regressed onto performance on the Tower of London planning task while accounting for moderating effects of age and sex on this interrelation. Multiple regression analysis revealed an association of planning performance and mid-dlPFC gray matter density that was especially strong in late adolescence and early twenties. As expected, for males better plannin…
Influence of cognitive-motor expertise on brain dynamics of anticipatory-based outcome processing.
2019
Motor experience plays an important role in the ability to anticipate action outcomes, but little is known about the brain processes through which it modulates the preparation for unexpected events. To address this issue, EEG was employed while table tennis players and novices observed videos of serves in order to predict the expected ball direction based on the kinematics of a model's movement. Furthermore, we manipulated the congruency between the model's body kinematics and the subsequent ball trajectory while assessing the cerebral cortical activity of novices and experts to understand how experts respond to unexpected outcomes. Experts were more accurate in predicting the ball trajecto…
Eyes open and eyes closed as rest conditions: impact on brain activation patterns
2003
The patterns of associated brain activations during eyes-open and eyes-closed states in complete darkness considerably differ in fMRI. An "interoceptive" state with the eyes closed is characterized by visual cortex activation, while an "exteroceptive" state with the eyes open is characterized by ocular motor system activity. The impact of the chosen rest condition (eyes open or eyes closed in complete darkness) on the pattern of brain activations during visual stimulation was evaluated in 14 healthy volunteers. During fixation or dim light room illumination, the activation of the visual cortex was larger with the eyes-open rest condition than with the eyes-closed rest condition; however, ac…
Autoimmune associations and autoantibody screening show focused recognition in patient subgroups with generalized myasthenia gravis
2013
Autoimmune associations in myasthenia gravis (MG)-patients and their relatives have not been re-assessed since their separation into early- or late-onset MG (EOMG, LOMG), or thymoma-associated MG. Here, we analysed 226 EOMG-, 97 LOMG-, and 150 thymoma-patients for autoimmune disorders in themselves and their relatives. From 283 of them sera were tested for different organ- and non-organ-specific autoantibodies (autoAbs) by immunofluorescence test (IFT) and ELISA; genotyping was performed in 213 patients. Relatives with autoimmune disorders were reported by more patients with EOMG (40% of 210) than LOMG (20% of 89; p0.01) than thymomas (8% of 150; p0.001). In 150 genotyped EOMG-females, the …
Cyclical changes of cortical excitability and metaplasticity in migraine: evidence from a repetitive transcranial magnetic stimulation study.
2013
The primary brain dysfunctions leading to the onset of a migraine attack remain largely unknown. Other important open questions concern the mechanisms of initiation, continuation, and termination of migraine pain, and the changes in brain function underlying migraine transformation. Brief trains of high-frequency repetitive transcranial magnetic stimulation (rTMS), when applied to the primary motor cortex at suprathreshold intensity (⩾120% of resting motor threshold [RMT]), elicit in healthy subjects a progressive, glutamate-dependent facilitation of the motor evoked potentials (MEP). Conversely, in conditions of increased cortical excitability, the rTMS trains induce inhibitory MEP respons…
Large-scale network architecture and associated structural cortico-subcortical abnormalities in patients with sleep/awake-related seizures.
2019
Study objectives In this study, we aimed to estimate the alterations of brain networks and structural integrity linked to seizure occurrence during sleep and awake states. Methods Using a graph theory approach to magnetic resonance imaging-derived volumes of cortical and subcortical regions, we investigated the topological organization of structural networks in patients with sleep seizures (n = 13), patients with awake seizures (n = 12), and age- and sex-matched healthy controls (n = 10). Abnormalities in regional structural substrates (cortical volume/surface area, subcortical volumes) associated with sleep seizures and awake seizures were further analyzed. Results Brain networks in patien…