Search results for " Mapping"
showing 10 items of 1411 documents
A Multi-Variate Predictability Framework to Assess Invasive Cardiac Activity and Interactions during Atrial Fibrillation
2017
Objective: This study introduces a predictability framework based on the concept of Granger causality (GC), in order to analyze the activity and interactions between different intracardiac sites during atrial fibrillation (AF). Methods: GC-based interactions were studied using a three-electrode analysis scheme with multi-variate autoregressive models of the involved preprocessed intracardiac signals. The method was evaluated in different scenarios covering simulations of complex atrial activity as well as endocardial signals acquired from patients. Results: The results illustrate the ability of the method to determine atrial rhythm complexity and to track and map propagation during AF. Conc…
The banding pattern of polytene chromosomes of Drosophila guanche compared with that of D. subobscura.
1987
A detailed map of the salivary gland chromosomes of Drosophila guanche is presented and compared to the standard gene arrangements of D. subobscura. Generally, the polytene chromosomc banding patterns of the two species show a high degrce of homology. Only Segment I of the sex chromosome (Chromosome A) shows marked differences. The banding pattern proposed for this segment in D. guanche could have originated from a cluster of overlapping inversions including A1 arrangement.
Functional brain imaging: a window into the visuo-vestibular systems
2007
Advances have been made in identifying how areas involved in processing vestibular, ocular motor, and visual information are represented in the human cortex as well as the cortical interaction between these systems in healthy subjects.While we know how some vestibular and ocular motor disorders modify visuo-vestibular interaction by changing the 'normal' cortical activation-deactivation patterns, it is still early days in functional magnetic resonance imaging studies of patients with specific disorders. Findings from current brain imaging studies of several vestibular, ocular motor, and cerebellar disorders are presented.The promise of more insights into the complex neuronal networks of the…
Early histological maturation in the hippocampus of the guinea pig.
2000
The vesicular zinc-rich synaptic systems of the principal neurons of the hippocampus are well developed in newborn guinea pigs, a precocial species. In addition, alvear and fimbrial myelinated fibers as well as significant inhibitory interneurons (i.e. somatostatin, parvalbumin and opioid immunoreactive hippocampal interneurons) are also well developed. On the contrary, neither vesicular zinc synapses nor myelinated fibers nor the above mentioned immunoreactive interneurons are detectable in newborn specimens of other related altricial species such as rats or rabbits. These data suggest that early maturation of a highly integrative center related to cognitive map building such as the hippoc…
Evaluation of movement and brain activity
2021
Clinical neurophysiology studies can contribute important information about the physiology of human movement and the pathophysiology and diagnosis of different movement disorders. Some techniques can be accomplished in a routine clinical neurophysiology laboratory and others require some special equipment. This review, initiating a series of articles on this topic, focuses on the methods and techniques. The methods reviewed include EMG, EEG, MEG, evoked potentials, coherence, accelerometry, coherence, posturography (balance), gait, and sleep studies. Functional MRI (fMRI) is also reviewed as a physiological method that can be used independently or together with other methods. A few applicat…
Erfassung von Neurotransmitterinteraktionen mit PET und SPECT durch pharmakologische Challenge-Paradigmen
2000
Functional brain imaging with positron emission tomography (PET) and single photon emission computerized tomography (SPECT) enables the in vivo study of specific neurochemical processes in the context of normal regulatory mechanisms and pathophysiological alterations of the brain. By combining these methods with pharmacological challenge-paradigms, the study of functional interactions of different neurotransmitter systems is possible. This review will present data from animal and healthy volunteer studies as well as first data from investigations in different patient populations with regard to this research direction. Especially, interactions of different neurotransmitter systems with the d…
Non-invasive Spatial Mapping of Frequencies in Atrial Fibrillation: Correlation With Contact Mapping
2021
[EN] Introduction: Regional differences in activation rates may contribute to the electrical substrates that maintain atrial fibrillation (AF), and estimating them non-invasively may help guide ablation or select anti-arrhythmic medications. We tested whether non-invasive assessment of regional AF rate accurately represents intracardiac recordings. Methods: In 47 patients with AF (27 persistent, age 63 +/- 13 years) we performed 57-lead non-invasive Electrocardiographic Imaging (ECGI) in AF, simultaneously with 64-pole intracardiac signals of both atria. ECGI was reconstructed by Tikhonov regularization. We constructed personalized 3D AF rate distribution maps by Dominant Frequency (DF) ana…
Risk Stratification by nrTMS Language Mapping
2017
Resecting language-eloquent brain lesions is a major challenge in neurosurgery since we need to weight the risks of worsening the patients’ functional integrity and achieving a maximum safe resection. Although relevant functional brain structures can be identified intraoperatively by direct cortical mapping during awake surgery, a preoperative identification of functional anatomy is recommended in order to gauge surgical risks, evaluate resectability, plan the surgical approach, and identify potential starting points for intraoperative stimulation mapping.
Recurrence quantification analysis as a tool for complex fractionated atrial electrogram discrimination
2012
International audience; Atrial fibrillation is the most encountered pathology of the heart rate. The reasons of its occurrence and its particular characteristics remain unknown, resulting from complex phenomena interaction. From these interactions emerges Complex Fractionated Atrial Electrograms (CFAE) which are useful for the ablation procedure. This study presents a method based on nonlinear data analysis, the Recurrence Quantification Analysis (RQA) applied on intracardiac atrial electrograms to detect CFAE particularities. The results obtained on areas previously tagged by a cardilogist show a good sensitivity to CFAE. Combination of RQA features offers a larger discrimination potential…
A topodiagnostic investigation on body lateropulsion in medullary infarcts.
2005
Body lateropulsion may occur without signs of vestibular dysfunction and vestibular nucleus involvement. The authors examined 10 such patients with three-dimensional brainstem mapping. Body lateropulsion without limb ataxia reflected an impairment of vestibulospinal postural control caused by a lesion of the descending lateral vestibulospinal tract, whereas body lateropulsion with limb ataxia was probably the consequence of impaired or absent proprioceptive information caused by a lesion of the ascending dorsal spino-cerebellar tract.