Search results for "Prefrontal Cortex"
showing 10 items of 323 documents
Central activation by histamine-induced itch: analogies to pain processing: a correlational analysis of O-15 H2O positron emission tomography studies
2001
The aim of this study was to identify the functional cerebral network involved in the central processing of itch and to detect analogies and differences to previously identified cerebral activation patterns triggered by painful noxious stimuli. Repeated positron emission tomography regional cerebral blood flow (rCBF) measurements using O15-labeled water were performed in six healthy right-handed male subjects (mean age 32 +/- 2 years). Each subject underwent 12 sequential rCBF measurements. In all subjects a standardized skin prick test was performed on the right forearm 2 min before each rCBF measurement. For activation, histamine was applied in nine tests in logarithmically increasing con…
Distributed BOLD-response in association cortex vector state space predicts reaction time during selective attention.
2006
Human cortical information processing is thought to be dominated by distributed activity in vector state space (Churchland, P.S., Sejnowski, T.J., 1992. The Computational Brain. MIT Press, Cambridge.). In principle, it should be possible to quantify distributed brain activation with independent component analysis (ICA) through vector-based decomposition, i.e., through a separation of a mixture of sources. Using event-related functional magnetic resonance imaging (fMRI) during a selective attention-requiring task (visual oddball), we explored how the number of independent components within activated cortical areas is related to reaction time. Prior to ICA, the activated cortical areas were d…
Localization of Brain Networks Engaged by the Sustained Attention to Response Task Provides Quantitative Markers of Executive Impairment in Amyotroph…
2020
Abstract Objective: To identify cortical regions engaged during the sustained attention to response task (SART) and characterize changes in their activity associated with the neurodegenerative condition amyotrophic lateral sclerosis (ALS). Methods: High-density electroencephalography (EEG) was recorded from 33 controls and 23 ALS patients during a SART paradigm. Differences in associated event-related potential peaks were measured for Go and NoGo trials. Sources active during these peaks were localized, and ALS-associated differences were quantified. Results: Go and NoGo N2 and P3 peak sources were localized to the left primary motor cortex, bilateral dorsolateral prefrontal cortex (DLPFC),…
Don't stress, it's under control: Neural correlates of stressor controllability in humans
2021
Abstract Animal research has repeatedly shown that control is a key variable in the brain's stress response. Uncontrollable stress triggers a release of monoamines, impairing prefrontal functions while enhancing subcortical circuits. Conversely, control over an adverse event involves prefrontally mediated downregulation of monoamine nuclei and is considered protective. However, it remains unclear to what extent these findings translate to humans. During functional magnetic resonance imaging, we subjected participants to controllable and uncontrollable aversive but non-painful electric stimuli, as well as to a control condition without aversive stimulation. In each trial, a symbol signalled …
Segregation of areas related to visual working memory in the prefrontal cortex revealed by rTMS.
2002
The functional organization of working memory (WM) in the human prefrontal cortex remains unclear. Storage and processing functions might be segregated in ventral and dorsal areas of the prefrontal cortex, respectively. If so, storage functions might be spared, irrespective of informational domain, following damage or dysfunction in dorsolateral areas. Alternatively, WM and prefrontal function in general might be segregated according to informational domains (e.g. spatial versus object-based information). In the present study we used repetitive transcranial magnetic stimulation (rTMS) to directly test these competing hypotheses. We applied rTMS to transiently and selectively disrupt the fun…
Chronometry of parietal and prefrontal activations in verbal working memory revealed by transcranial magnetic stimulation.
2003
We explored the temporal dynamics of parietal and prefrontal cortex involvement in verbal working memory employing single-pulse transcranial magnetic stimulation (TMS). In six healthy volunteers the left or right inferior parietal and prefrontal cortex was stimulated with the aid of a frameless stereotactic system. TMS was applied at 10 different time points 140-500 ms into the delay period of a two-back verbal working memory task. A choice reaction task was used as a control task. Interference with task accuracy was induced by TMS earlier in the parietal cortex than in the prefrontal cortex and earlier over the right than the left hemisphere. This suggests a propagation of information flow…
The influence of rTMS over prefrontal and motor areas in a morphological task: grammatical vs. semantic effects
2008
We investigated the differential role of two frontal regions in the processing of grammatical and semantic knowledge. Given the documented specificity of the prefrontal cortex for the grammatical class of verbs, and of the primary motor cortex for the semantic class of action words, we sought to investigate whether the prefrontal cortex is also sensitive to semantic effects, and whether the motor cortex is also sensitive to grammatical class effects. We used repetitive transcranial magnetic stimulation (rTMS) to suppress the excitability of a portion of left prefontal cortex (first experiment) and of the motor area (second experiment). In the first experiment we found that rTMS applied to t…
The what and how of observational learning
2007
Abstract Neuroimaging evidence increasingly supports the hypothesis that the same neural structures subserve the execution, imagination, and observation of actions. We used repetitive transcranial magnetic stimulation (rTMS) to investigate the specific roles of cerebellum and dorsolateral prefrontal cortex (DLPFC) in observational learning of a visuomotor task. Subjects observed an actor detecting a hidden sequence in a matrix and then performed the task detecting either the previously observed sequence or a new one. rTMS applied over the cerebellum before the observational training interfered with performance of the new sequence, whereas rTMS applied over the DLPFC interfered with performa…
The role of the right temporo-parietal junction in social decision-making
2018
Identifying someone else's noncooperative intentions can prevent exploitation in social interactions. Hence, the inference of another person's mental state might be most pronounced in order to improve social decision‐making. Here, we tested the hypothesis that brain regions associated with Theory of Mind (ToM), particularly the right temporo–parietal junction (rTPJ), show higher neural responses when interacting with a selfish person and that the rTPJ‐activity as well as cooperative tendencies will change over time. We used functional magnetic resonance imaging (fMRI) and a modified prisoner's dilemma game in which 20 participants interacted with three fictive playing partners who behaved a…
Confabulation: damage to a specific inferior medial prefrontal system
2008
Confabulation, the pathological production of false memories, occurs following a variety of aetiologies involving the frontal lobes, and is frequently held to be underpinned by combined memory and executive deficits. However, the critical frontal regions and specific cognitive deficits involved are unclear. Studies in amnesic patients have associated confabulation with damage to the orbital and ventromedial prefrontal cortices. However, neuroimaging studies have associated memory-control processes which are assumed to underlie confabulation with the right lateral prefrontal cortex. We used a confabulation battery to investigate the occurrence and localisation of confabulation in an unselect…