Testing gustatory function using either a forced-choice or a non-forced-choice paradigm - Does it make a difference?

BACKGROUND: Recently more interest is evolving for research on gustatory function, also due to findings of â€extraoral†taste receptors with postulated participation in a pathogen detection network. Also, bitter taste function seems to be reduced in patients with chronic rhinosinusitis. For testing gustatory function â€taste strips†(TS) have been validated in a forced-choice (fc) and a non-forced-choice (nfc) paradigm and used in several studies. Purpose of the investigation was to evaluate possible differences of named modalities. METHODOLOGY: Healthy subjects (n=102) with subjective normal gustatory function and patients (n=30) with potential taste dysfunction were included. All participants were tested twice (using TS in four concentrations of sweet, sour, salty, and bitter taste), either starting with a fc or a nfc paradigm. RESULTS: In tested patients there was a difference between fc and nfc procedure with higher results for bitter in the fc testing procedure, while other qualities did not differ. This effect was also visible in the overall participants with higher scores in the fc procedure for bitter taste. CONCLUSION: TS are valid to be used in a forced and a non-forced choice paradigm, with bitter taste showing slightly higher scores in forced-choice testing. Future investigators with focus on bitter taste perception should be particularly cautious when comparing results in regard to testing procedure.

Solvers for the cardiac bidomain equations.

The bidomain equations are widely used for the simulation of electrical activity in cardiac tissue. They are especially important for accurately modeling extracellular stimulation, as evidenced by their prediction of virtual electrode polarization before experimental verification. However, solution of the equations is computationally expensive due to the fine spatial and temporal discretization needed. This limits the size and duration of the problem which can be modeled. Regardless of the specific form into which they are cast, the computational bottleneck becomes the repeated solution of a large, linear system. The purpose of this review is to give an overview of the equations and the methods by which they have been solved. Of particular note are recent developments in multigrid methods, which have proven to be the most efficient.

Evaluating intramural virtual electrodes in the myocardial wedge preparation: simulations of experimental conditions.

While defibrillation is the only means for prevention of sudden cardiac death, key aspects of the process, such as the intramural virtual electrodes (VEs), remain controversial. Experimental studies had attempted to assess intramural VEs by using wedge preparations and recording activity from the cut surface; however, applicability of this approach remains unclear. These studies found, surprisingly, that for strong shocks, the entire cut surface was negatively polarized, regardless of boundary conditions. The goal of this study is to examine, by means of bidomain simulations, whether VEs on the cut surface represent a good approximation to VEs in depth of the intact wall. Furthermore, we aim to explore mechanisms that could give rise to negative polarization on the cut surface. A model of wedge preparation was used, in which fiber orientation could be changed, and where the cut surface was subjected to permeable and impermeable boundary conditions. Small-scale mechanisms for polarization were also considered. To determine whether any distortions in the recorded VEs arise from averaging during optical mapping, a model of fluorescent recording was employed. The results indicate that, when an applied field is spatially uniform and impermeable boundary conditions are enforced, regardless of the fiber orientation VEs on the cut surface faithfully represent those intramurally, provided tissue properties are not altered by dissection. Results also demonstrate that VEs are sensitive to the conductive layer thickness above the cut surface. Finally, averaging during fluorescent recordings results in large negative VEs on the cut surface, but these do not arise from small-scale heterogeneities.

Image-Based Personalization of Cardiac Anatomy for Coupled Electromechanical Modeling.

Computational models of cardiac electromechanics (EM) are increasingly being applied to clinical problems, with patient-specific models being generated from high fidelity imaging and used to simulate patient physiology, pathophysiology and response to treatment. Current structured meshes are limited in their ability to fully represent the detailed anatomical data available from clinical images and capture complex and varied anatomy with limited geometric accuracy. In this paper, we review the state of the art in image-based personalization of cardiac anatomy for biophysically detailed, strongly coupled EM modeling, and present our own tools for the automatic building of anatomically and structurally accurate patient-specific models. Our method relies on using high resolution unstructured meshes for discretizing both physics, electrophysiology and mechanics, in combination with efficient, strongly scalable solvers necessary to deal with the computational load imposed by the large number of degrees of freedom of these meshes. These tools permit automated anatomical model generation and strongly coupled EM simulations at an unprecedented level of anatomical and biophysical detail.

Kinematic analysis of facial behaviour in patients with schizophrenia under emotional stimulation by films with "Mr. Bean".

In schizophrenic patients, motor functioning is substantially disturbed. Kinematic analysis is useful in examining this motor dysfunction. Using kinematic analysis, we aimed to investigate facial movement in schizophrenic patients responding to humorous film stimuli ("Mr. Bean"). Ultrasound markers were attached to pre-defined facial points while subjects watched a funny film sketch. The study included 21 schizophrenic in-patients (13 men, 8 women; mean (S.D.) age: 32.1 (10.4) years) and 30 healthy individuals (12 men, 18 women; mean (S.D.) age: 35.7 (11.0) years). Unmedicated schizophrenic patients showed an abnormally high initial velocity of laughing (IV), while patients treated with typical neuroleptics demonstrated an abnormally low IV. There was a significant positive correlation between severity of negative symptoms and IV. Kinematical analysis of facial movement using IV could help to distinguish subclinical Parkinsonian syndromes induced by typical neuroleptics from negative symptoms of schizophrenia.

Prefrontal cortex modulation of mood and emotionally induced facial expressions: a transcranial magnetic stimulation study.

Repetitive transcranial magnetic stimulation (rTMS) can serve as a tool to experimentally test hypotheses of prefrontal cortex (PFC) modulation of emotions. The present study used rTMS to test whether self-rated mood and emotionally induced facial expressions are hemispherically lateralized depending on their valence, as indicated by previous studies. Healthy volunteers underwent mood self-rating and computerized analysis of emotionally induced facial expressions before and after rTMS of left or right PFC. Facial expression analysis revealed lateralized changes of facial expressions after rTMS, whereas changes of subjective mood ratings did not show a hemispheric lateralization. On the basis of this study, the authors propose to combine rTMS and facial expression analysis for further studies of the cortical modulation of emotions in humans.

A novel vacuum device for extremity immobilisation during digital angiography: preliminary clinical experiences.

Our objective was to develop and evaluate a non-invasive device for rigid immobilisation during extremity angiography. The patented BodyFix immobilisation device (Medical Intelligence, Schwabmünchen, Germany) consists of a vacuum pump connected to special cushions and a plastic foil that covers the body part to be immobilised. First, the patient's extremity is covered by a thin plastic bag and then wrapped in one of the cushions, placed on the top of the therapy couch, and covered with the plastic foil. The air is evacuated from the cushion under the covering foil by the vacuum pump, resulting a hardening of the cushion and thus immobilisation of the patient's extremity. The rigid immobilisation resulted in a complete absence of motion artefacts in the majority of patients. No pixeling of the images was required in any of the 100 patients vs 32% in the control group. Repetition of series could be avoided in all cases and a substantial increase in the quality of the images was obtained. Setup of the device takes an additional 1-2 min. Vacuum immobilisation allows for comfortable, effective immobilisation during digital subtraction angiography, eliminating motion artefacts. This device has become an indispensable tool in daily clinical routine at our department.