Search results for "brain"
showing 10 items of 3997 documents
Integration of sensory information precedes the sensation of vection: a combined behavioral and event-related brain potential (ERP) study.
2014
Illusory self-motion (known as vection) describes the sensation of ego-motion in the absence of physical movement. Vection typically occurs in stationary observers being exposed to visual information that suggest self-motion (e.g. simulators, virtual reality). In the present study, we tested whether sensory integration of visual information triggers vection: participants (N=13) perceived patterns of moving altered black-and-white vertical stripes on a screen that was divided into a central and a surrounding peripheral visual field. In both fields the pattern was either moving or stationary, resulting in four combinations of central and peripheral motions: (1) central and peripheral stripes …
Precision and Bias of Target-Controlled Prolonged Propofol Infusion for General Anesthesia and Sedation in Neurosurgical Patients
2018
The aim of this study was to determine the relationship, precision, and bias of a propofol target-controlled infusion (TCI) system during prolonged infusion in neurosurgical patients. We retrospectively included patients undergoing general anesthesia for elective neurosurgical removal of brain tumors and postoperative sedation in the intensive care unit over a period of 3 months. TCI of propofol (Diprifusor - Marsh model) and remifentanil were used for general anesthesia and sedation. We compared propofol blood concentration (Cmeas) measured by liquid chromatography-mass spectroscopy with predicted concentrations (Cpred) by the TCI system at 40 minutes (T0), 2 hours (T1), and 4 hours (T2) a…
Forensic microbiology applications: A systematic review.
2019
Abstract According to the Human Microbiome Project (HMP), a healthy human body contains ten times more microbes than human cells. Microbial communities colonize different organs of the body, playing fundamental roles both in human health and disease. Despite the vast scientific knowledge of the role of microbial communities in a living body, little is known at present about microbial changes occurring after death, thus leading many authors to investigate the composition of the thanatomicrobiome and its potential applications in the forensic field. The aim of the following review is to provide a general overview of the advances of postmortem microbiology research, mainly focusing on the role…
The hippocampus is required for short-term topographical memory in humans.
2007
The hippocampus plays a crucial role within the neural systems for long-term memory, but little if any role in the short-term retention of some types of stimuli. Nonetheless, the hippocampus may be specialized for allocentric topographical processing, which impacts on short-term memory or even perception. To investigate this we developed performance-matched tests of perception (match-to-sample) and short-term memory (2 s delayed-match-to-sample) for the topography and for the nonspatial aspects of visual scenes. Four patients with focal hippocampal damage and one with more extensive damage, including right parahippocampal gyrus, were tested. All five patients showed impaired topographical m…
Primary motor area contribution to attentional reorienting after distraction
2008
The anatomical structures involved in distraction-related processing in the auditory domain were investigated using magnetoencephalography. Participants performed a duration-discrimination task on a sequence of 200 and 400 ms long tones. Infrequent (12%) task-irrelevant pitch changes resulted in slower discriminative responses and more errors. Event-related potentials to these changes show an increased N1, a mismatch negativity, a P3a, and a reorienting negativity. The event-related magnetic fields revealed focal activities in superior and medial temporal areas in the N1/mismatch negativity time range. No significant activity was found in the P3a interval. In the reorienting negativity inte…
Parafoveal versus foveal N400s dissociate spreading activation from contextual fit.
2009
Using concurrent electroencephalogram and eye movement measures to track natural reading, this study shows that N400 effects reflecting predictability are dissociable from those owing to spreading activation. In comparing predicted sentence endings with related and unrelated unpredicted endings in antonym constructions ('the opposite of black is white/yellow/nice'), fixation-related potentials at the critical word revealed a predictability-based N400 effect (unpredicted vs. predicted words). By contrast, event-related potentials time locked to the last fixation before the critical word showed an N400 only for the nonrelated unpredicted condition (nice). This effect is attributed to a parafo…
Pitch accent type affects the N400 during referential processing
2010
Discourse processing depends on semantic memory as well as maintaining and updating of a mental model. Using event-related potentials, we investigated how a referent's information status (new, accessible, given) is processed in combination with three different prosodic realizations (an appropriate accent and two inappropriate accents). The data reveal a biphasic N400-late positivity pattern, indicating that prosodic information affects an early discourse linking stage, during which prominence information reflecting a referent's accessibility is computed (N400), and a later discourse updating stage, during which conflicts between prosodic information and a referent's actual information statu…
Neural Mechanisms of Placebo Anxiolysis
2015
The beneficial effects of placebo treatments on fear and anxiety (placebo anxiolysis) are well known from clinical practice, and there is strong evidence indicating a contribution of treatment expectations to the efficacy of anxiolytic drugs. Although clinically highly relevant, the neural mechanisms underlying placebo anxiolysis are poorly understood. In two studies in humans, we tested whether the administration of an inactive treatment along with verbal suggestions of anxiolysis can attenuate experimentally induced states of phasic fear and/or sustained anxiety. Phasic fear is the response to a well defined threat and includes attentional focusing on the source of threat and concomitant …
Visual distraction: a behavioral and event-related brain potential study in humans.
2006
Recent studies reported that the detection of changes in the visual stimulation results in distraction of cognitive processing. From event-related brain potentials it was argued that distraction is triggered by the automatic detection of deviants. We tested whether distraction effects are confined to the detection of a deviation or can be triggered by changes per se, namely by rare stimuli that were not deviant with respect to the stimulation. The results obtained comparable early event-related brain potential effects for rare and deviant stimuli, suggesting an automatic detection of these changes. In contrast, behavioral distraction and attention-related event-related brain potential compo…
Time Course of 5-HT2A Receptor Occupancy in the Human Brain after a Single Oral Dose of the Putative Antipsychotic Drug MDL 100,907 Measured by Posit…
1997
MDL 100,907 is a potent and selective antagonist of 5-HT2A serotonin receptors. Animals studies suggest that MDL 100,907 may behave as an atypical antipsychotic drug. Positron emission tomograph (PET) using [11C]NMSP as the radiotracer was used to define the time course of 5-HT2 receptor occupancy in the human frontal cerebral cortex after a single oral dose of MDL 100,907 (10 or 20 mg) in nine healthy subjects. After the baseline scan each subject was studied three times post dosing at various time points. 5-HT2 occupancies were in the range of 70 and 90% after each dose. While the occupancy remains in this range over 24 hours after 20 mg MDL 100,907, it decreases by about 20% at 24 hours …