Search results for "processi"
showing 10 items of 9638 documents
fMRI characterization of visual working memory recognition
2013
Encoding and maintenance of information in visual working memory have been extensively studied, highlighting the crucial and capacity-limiting role of fronto-parietal regions. In contrast, the neural basis of recognition in visual working memory has remained largely unspecified. Cognitive models suggest that recognition relies on a matching process that compares sensory information with the mental representations held in memory. To characterize the neural basis of recognition we varied both the need for recognition and the degree of similarity between the probe item and the memory contents, while independently manipulating memory load to produce load-related fronto-parietal activations. fMR…
Topodiagnostic value of blink reflex R1 changes: a digital postprocessing MRI correlation study.
2001
The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem lesions as identified by magnetic resonance imaging (MRI) of patients with isolated R1 pathology were superimposed into a stereotactic anatomical atlas using a new method of digital postprocessing. Isolated acute brainstem lesions were documented by diffusion-weighted MRI in 12 of 24 patients with unilateral R1 pathology. The lesions were located in the ipsilateral mid- to lower pons. In three patients only, the lesion had partial contact with the principal sensory nucleus of the trigeminal nerve (PSN) on at least one level. In two patients, the …
Complex network analysis of resting-state fMRI of the brain.
2016
Due to the fact that the brain activity hardly ever diminishes in healthy individuals, analysis of resting state functionality of the brain seems pertinent. Various resting state networks are active inside the idle brain at any time. Based on various neuro-imaging studies, it is understood that various structurally distant regions of the brain could be functionally connected. Regions of the brain, that are functionally connected, during rest constitutes to the resting state network. In the present study, we employed the complex network measures to estimate the presence of community structures within a network. Such estimate is named as modularity. Instead of using a traditional correlation …
Magnetic molecularly imprinted polymers for the selective determination of cocaine by ion mobility spectrometry
2018
Abstract Magnetic molecularly imprinted polymers (MMIPs) were prepared for cocaine recognition by bulk polymerization in the presence of magnetic nanoparticles (MNPs). Two reagents (polyethylene glycol (PEG) and 3-(trimethoxysilyl)propyl methacrylate (V)) were used for MNPs modification. MMIPs were characterized and compared in terms of loading capacity, reusability, accuracy and precision for the extraction of cocaine from saliva samples. It was observed that V-MMIPs gave higher physical stability than PEG-MMIPs. Thus, V-MMIP were used for the analysis of cocaine users saliva. The developed procedure based on ion mobility spectrometry (IMS) provided limits of detection and quantification o…
CATCHING FALLING OBJECTS: THE ROLE OF THE CEREBELLUM IN PROCESSING SENSORY-MOTOR ERRORS THAT MAY INFLUENCE UPDATING OF FEEDFORWARD COMMANDS. AN fMRI …
2011
Import JabRef | WosArea Neurosciences and Neurology; International audience; The human motor system continuously adapts to changes in the environment by comparing differences between the brain's predicted outcome of a certain behavior and the observed outcome. This discrepancy signal triggers a sensory-motor error and it is assumed that the cerebellum is a key structure in updating this error and associated feedforward commands. Using fMRI, the aim of the present study was to determine the main cerebellar structures that are involved in the processing of sensory-motor errors and in updating feedforward commands when simply catching a falling ball without displacement of the hand. Subjects o…
Parotid sialosis: morphometrical analysis of the glandular parenchyme and stroma among diabetic and alcoholic patients
2009
J Oral Pathol Med (2010) 39: 10–15 Background: Among the agents that cause parotid sialosis, diabetes mellitus type 2 and chronic alcoholism are included. In this study, the morphometrical modifications in the diabetic parotid sialosis were determined to compare them with the histopathological characteristics of alcoholic parotid sialosis. Methods: Five parotid biopsy samples obtained from patients with diabetic sialosis, 12 samples from patients with alcoholic sialosis and seven from individuals without these pathologies (control group) were analyzed. A morphometrical study of parotid parenchyme and stroma, using a digital image analyzer attached to an optical microscope, was carried out…
Prospective, blinded comparison of cytology and DNA-image cytometry of brush biopsies for early detection of oral malignancy
2012
summary Objectives: Adjunctive techniques like DNA image cytometry (DNA-ICM) have been attributed to enhance the diagnostic performance of oral brush biopsies. The aim of the study was an evaluation of brush biopsies, analysed according to morphological criteria and by DNA-ICM vs. histological findings in a blinded prospective trial. Materials and methods: Eighty eight brush biopsies of 70 patients were sampled. Only clinical suspicious but not evident malignant oral lesions were included. Clinical diagnosis was leukoplakia (n = 36), lichen planus (n = 18), verruciform erythroplakia (n = 12), erythroleukoplakia (n = 9), erosion (n = 7) and induration (n = 6). Evaluation was conducted via hi…
Acute Alcohol Effects on Neuronal and Attentional Processing: Striatal Reward System and Inhibitory Sensory Interactions under Acute Ethanol Challenge
2004
The acute influence of ethanol on cerebral activity induces complex psycho-physiological effects that are considerably more pronounced during acute ethanol influx than during maximal blood alcohol concentration (elimination phase). Despite the psychiatric and forensic relevance of these different ethanol effects, the underlying neuronal mechanisms are still unclear. In total, 20 male healthy volunteers were investigated each with three different experimental conditions in a randomized order using an intravenous ethanol challenge (40 g bolus infusion): during influx phase, elimination phase, and under placebo condition. During and after the ethanol (or placebo) infusion, neuropsychological t…
Cognitive and Motor Loops of the Human Cerebro-cerebellar System
2010
Abstract We applied fMRI and diffusion-weighted MRI to study the segregation of cognitive and motor functions in the human cerebro-cerebellar system. Our fMRI results show that a load increase in a nonverbal auditory working memory task is associated with enhanced brain activity in the parietal, dorsal premotor, and lateral prefrontal cortices and in lobules VII–VIII of the posterior cerebellum, whereas a sensory-motor control task activated the motor/somatosensory, medial prefrontal, and posterior cingulate cortices and lobules V/VI of the anterior cerebellum. The load-dependent activity in the crus I/II had a specific relationship with cognitive performance: This activity correlated negat…
Topicality matters: Position-specific demands on Chinese discourse processing
2011
We report an event-related potential study designed to explore the nature of context-induced topicality in Chinese discourse processing. Topic is what an utterance is about and represents the most prominent discourse element, which occurs sentence-initially in Chinese. We tested question-answer pairs consisting of topic and non-topic questions followed by different continuations (Topic-Continuity, Topic-Shift, Novel-Topic). ERPs were measured at distinct sentential positions and revealed that sentence-initially information processing is guided by topicality, which affects N400 and Late Positivity effects alike. In non-initial positions, the given-new distinction is the dominant principle, a…