Search results for "Process"
showing 10 items of 22310 documents
Quantifying Net Synergy/Redundancy of Spontaneous Variability Regulation via Predictability and Transfer Entropy Decomposition Frameworks.
2017
Objective: Indexes assessing the balance between redundancy and synergy were hypothesized to be helpful in characterizing cardiovascular control from spontaneous beat-to-beat variations of heart period (HP), systolic arterial pressure (SAP), and respiration (R). Methods: Net redundancy/synergy indexes were derived according to predictability and transfer entropy decomposition strategies via a multivariate linear regression approach. Indexes were tested in two protocols inducing modifications of the cardiovascular regulation via baroreflex loading/unloading (i.e., head-down tilt at −25° and graded head-up tilt at 15°, 30°, 45°, 60°, 75°, and 90°, respectively). The net redundancy/synergy of …
Neural dynamics of learning sound-action associations.
2008
A motor component is pre-requisite to any communicative act as one must inherently move to communicate. To learn to make a communicative act, the brain must be able to dynamically associate arbitrary percepts to the neural substrate underlying the pre-requisite motor activity. We aimed to investigate whether brain regions involved in complex gestures (ventral pre-motor cortex, Brodmann Area 44) were involved in mediating association between novel abstract auditory stimuli and novel gestural movements. In a functional resonance imaging (fMRI) study we asked participants to learn associations between previously unrelated novel sounds and meaningless gestures inside the scanner. We use functio…
Neural correlates of interference inhibition, action withholding and action cancelation in adult ADHD
2011
Attention-Deficit/Hyperactivity Disorder (ADHD) is marked by inhibitory and attentional deficits which can persist into adulthood. Those deficits have been associated with dysfunctional fronto-striatal and fronto-parietal circuits. The present study sought to delineate neural correlates of component specific inhibitory deficits in adult ADHD using functional magnetic resonance imaging (fMRI). 20 adult ADHD patients and 24 matched healthy controls were included. Brain activation was assessed during three stages of behavioral inhibition, i.e. interference inhibition (Simon task), action withholding (Go/no-go task) and action cancelation (Stop-signal task). Behaviorally, ADHD patients were aff…
Nicotine effects on anterior cingulate cortex in schizophrenia and healthy smokers as revealed by EEG-informed fMRI
2012
Abstract Nicotine can have beneficial effects on attention performance and corresponding brain function in both schizophrenia patients and healthy controls, but it remains controversial whether nicotine affects brain function differentially in patients vs. controls. The effects of nicotine on brain activity elicited by attention-requiring oddball-type tasks have not been studied in schizophrenia patients. In this study we sought to investigate the impact of nicotine on the p300 evoked potential component and corresponding fMRI (functional magnetic resonance imaging) activation measures in schizophrenia patients and controls. Applying a double-blind, placebo-controlled cross-over design, the…
Interoceptive and multimodal functions of the operculo-insular cortex: tactile, nociceptive and vestibular representations.
2013
The operculo-insular cortex has been termed the 'homeostatic control center' or 'general magnitude estimator' of the human mind. In this study, somatosensory, nociceptive and caloric vestibular stimuli were applied to reveal, whether there are mainly common, or possibly specific regions activated by one modality alone and whether lateralization effects, time pattern differences or influences of the aversive nature of the stimuli could be observed. Activation of the dorsal posterior insula was caused by all stimuli alike thus terming this area multimodal. Early phases of the noxious heat and caloric vestibular stimulation led to responses in the anterior insula. Using conjunction analyses we…
Spatial variability of muscle activity during human walking: The effects of different EMG normalization approaches
2015
Human leg muscles are often activated inhomogeneously, e.g. in standing. This may also occur in complex tasks like walking. Thus, bipolar surface electromyography (sEMG) may not accurately represent whole muscle activity. This study used 64-electrode high-density sEMG (HD-sEMG) to examine spatial variability of lateral gastrocnemius (LG) muscle activity during the stance phase of walking, maximal voluntary contractions (MVCs) and maximal M-waves, and determined the effects of different normalization approaches on spatial and inter-participant variability. Plantar flexion MVC, maximal electrically elicited M-waves and walking at self-selected speed were recorded in eight healthy males aged 2…
Dental implants placed on bone subjected to vertical alveolar distraction show the same performance as those placed on primitive bone
2013
Introduction: Vertical osteogenic alveolar distraction (VOAD) allows for the augmentation of the alveolar ridge for the placement of dental implants in atrophic alveolar ridges. The goal of this paper is to assess long-term peri-implant bone resorption in implants placed on bones subjected to VOAD, comparing it with a group of patients who had implants placed directly on the alveolar bone without previous bone regeneration. Material and Methods: We conducted a follow-up study on 32 patients who were divided into two groups: The Distraction Group (14 patients), and the Distraction-Free Group (18 patients), who received a total of 100 implants. Peri-implant bone loss was measured by means of …
Illusion of Pain: Pre-existing Knowledge Determines Brain Activation of ‘Imagined Allodynia’
2007
Abstract Allodynia means that innocuous tactile stimulation is felt as pain. Accordingly, cerebral activations during allodynia or touch should markedly differ. The aim of this study was to investigate whether the imagination of allodynia affects brain processing of touch in healthy subjects. Seventeen healthy subjects divided into 2 subgroups were investigated: The first group (n = 7) was familiar with allodynia, based on previous pain studies, whereas the second group (n = 10) had never knowingly experienced allodynia. Using functional magnetic resonance imaging, 2 experimental conditions were investigated. In one condition the subjects were simply touched at their left hand, whereas duri…
Multiple Somatotopic Representations of Heat and Mechanical Pain in the Operculo-Insular Cortex: A High-Resolution fMRI Study
2010
Whereas studies of somatotopic representation of touch have been useful to distinguish multiple somatosensory areas within primary (SI) and secondary (SII) somatosensory cortex regions, no such analysis exists for the representation of pain across nociceptive modalities. Here we investigated somatotopy in the operculo-insular cortex with noxious heat and pinprick stimuli in 11 healthy subjects using high-resolution (2 × 2 × 4 mm) 3T functional magnetic resonance imaging (fMRI). Heat stimuli (delivered using a laser) and pinprick stimuli (delivered using a punctate probe) were directed to the dorsum of the right hand and foot in a balanced design. Locations of the peak fMRI responses were c…
Activation of the cortical pain network by soft tactile stimulation after injection of sumatriptan.
2006
The anti-migraine drug sumatriptan often induces unpleasant somatosensory side effects, including a dislike of being touched. With a double-blind cross-over design, we studied the effects of sumatriptan and saline on perception (visual analogue scale) and cortical processing (functional magnetic resonance imaging) of tactile stimulation in healthy subjects. Soft brush stroking on the calf (n = 6) was less pleasant (p < 0.04) and evoked less activation of posterior insular cortex in the sumatriptan compared to the saline condition. Soft brushing activated pain processing regions (anterior insular, lateral orbitofrontal, and anterior cingulate cortices, and medial thalamus) only in the sumatr…