scholarly journals Task switching challenge to reveal abnormal brain‐heart signatures in cognitively healthy individuals with abnormal CSF amyloid/tau

2021 ◽  
Vol 17 (S5) ◽  
Author(s):  
Rebecca Johnson Arechavala ◽  
Anqi Liu ◽  
Roger Rochart ◽  
Robert Kloner ◽  
Alfred N. Fonteh ◽  
...  
Author(s):  
B. J. Panessa-Warren ◽  
J. B. Warren ◽  
H. W. Kraner

Our previous studies have demonstrated that abnormally high amounts of calcium (Ca) and zinc (Zn) can be accumulated in human retina-choroid under pathological conditions and that barium (Ba), which was not detected in the eyes of healthy individuals, is deposited in the retina pigment epithelium (RPE), and to a lesser extent in the sensory retina and iris. In an attempt to understand how these cations can be accumulated in the vertebrate eye, a morphological and microanalytical study of the uptake and loss of specific cations (K, Ca,Ba,Zn) was undertaken with incubated Rana catesbiana isolated retina and RPE preparations. Large frogs (650-800 gms) were dark adapted, guillotined and their eyes enucleated in deep ruby light. The eyes were hemisected behind the ora serrata and the anterior portion of the eye removed. The eyecup was bisected along the plane of the optic disc and the two segments of retina peeled away from the RPE and incubated.


VASA ◽  
2012 ◽  
Vol 41 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Hoerth ◽  
Kundi ◽  
Katzenschlager ◽  
Hirschl

Background: Nailfold capillaroscopy (NVC) is a diagnostic tool particularly useful in the differential diagnosis of rheumatic and connective tissue diseases. Although successfully applied since many years, little is known about prevalence and distribution of NVC changes in healthy individuals. Probands and methods: NVC was performed in 120 individuals (57 men and 63 women; age 18 to 70 years) randomly selected according to predefined age and sex strata. Diseases associated with NVC changes were excluded. The nailfolds of eight fingers were assessed according to standardized procedures. A scoring system was developed based on the distribution of the number of morphologically deviating capillaries, microhaemorrhages, and capillary density. Results: Only 18 individuals (15 %) had no deviation in morphology, haemorrhages, or capillary density on any finger. Overall 67 % had morphological changes, 48 % had microhaemorrhages, and 40 % of volunteers below 40 years of age and 18 % above age 40 had less than 8 capillaries/mm. Among morphological changes tortous (43 %), ramified (47 %), and bushy capillaries (27 %) were the most frequently altered capillary types. A semiquantitative scoring system was developed in such a way that a score above 1 indicates an extreme position (above the 90th percentile) in the distribution of scores among healthy individuals. Conclusions: Altered capillaries occur frequently among healthy individuals and should be interpreted as normal unless a suspicious increase in their frequency is determined by reference to the scoring system. Megacapillaries and diffuse loss of capillaries were not found and seem to be of specific diagnostic value.


2018 ◽  
Vol 32 (3) ◽  
pp. 106-130 ◽  
Author(s):  
Zsófia Anna Gaál ◽  
István Czigler

Abstract. We used task-switching (TS) paradigms to study how cognitive training can compensate age-related cognitive decline. Thirty-nine young (age span: 18–25 years) and 40 older (age span: 60–75 years) women were assigned to training and control groups. The training group received 8 one-hour long cognitive training sessions in which the difficulty level of TS was individually adjusted. The other half of the sample did not receive any intervention. The reference task was an informatively cued TS paradigm with nogo stimuli. Performance was measured on reference, near-transfer, and far-transfer tasks by behavioral indicators and event-related potentials (ERPs) before training, 1 month after pretraining, and in case of older adults, 1 year later. The results showed that young adults had better pretraining performance. The reference task was too difficult for older adults to form appropriate representations as indicated by the behavioral data and the lack of P3b components. But after training older adults reached the level of performance of young participants, and accordingly, P3b emerged after both the cue and the target. Training gain was observed also in near-transfer tasks, and partly in far-transfer tasks; working memory and executive functions did not improve, but we found improvement in alerting and orienting networks, and in the execution of variants of TS paradigms. Behavioral and ERP changes remained preserved even after 1 year. These findings suggest that with an appropriate training procedure older adults can reach the level of performance seen in young adults and these changes persist for a long period. The training also affects the unpracticed tasks, but the transfer depends on the extent of task similarities.


Author(s):  
Nachshon Meiran ◽  
Ziv Chorev

Abstract. Participants switched between two randomly ordered discrimination tasks and each trial began with the presentation of a task cue instructing which task to execute. The authors induced phasic alertness by presenting a salient uninformative stimulus after the task cue was provided, and at variable intervals before the target stimulus was presented (Experiments 1-3) or before the task cue (Experiment 4). When the alerting stimulus preceded the target stimulus or the task cue by an optimal interval, RT was faster, indicating an alert state and the task-switching cost was reduced. These results support the suggestion of De Jong (Acta Psychologica, 1999 ) that alertness improves the overcoming of retrieval competition through improved goal representation, but also show that the effect is specific to the residual task-switching cost.


2013 ◽  
Vol 221 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Kerstin Jost ◽  
Wouter De Baene ◽  
Iring Koch ◽  
Marcel Brass

The role of cue processing has become a controversial topic in research on cognitive control using task-switching procedures. Some authors suggested a priming account to explain switch costs as a form of encoding benefit when the cue from the previous trial is repeated and hence challenged theories that attribute task-switch costs to task-set (re)configuration. A rich body of empirical evidence has evolved that indeed shows that cue-encoding repetition priming is an important component in task switching. However, these studies also demonstrate that there are usually substantial “true” task-switch costs. Here, we review this behavioral, electrophysiological, and brain imaging evidence. Moreover, we describe alternative approaches to the explicit task-cuing procedure, such as the usage of transition cues or the task-span procedure. In addition, we address issues related to the type of cue, such as cue transparency. We also discuss methodological and theoretical implications and argue that the explicit task-cuing procedure is suitable to address issues of cognitive control and task-set switching.


2013 ◽  
Vol 221 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Iring Koch ◽  
Marcel Brass
Keyword(s):  

Author(s):  
Thomas Kleinsorge ◽  
Gerhard Rinkenauer

In two experiments, effects of incentives on task switching were investigated. Incentives were provided as a monetary bonus. In both experiments, the availability of a bonus varied on a trial-to-trial basis. The main difference between the experiments relates to the association of incentives to individual tasks. In Experiment 1, the association of incentives to individual tasks was fixed. Under these conditions, the effect of incentives was largely due to reward expectancy. Switch costs were reduced to statistical insignificance. This was true even with the task that was not associated with a bonus. In Experiment 2, there was a variable association of incentives to individual tasks. Under these conditions, the reward expectancy effect was bound to conditions with a well-established bonus-task association. In conditions in which the bonus-task association was not established in advance, enhanced performance of the bonus task was accompanied by performance decrements with the task that was not associated with a bonus. Reward expectancy affected mainly the general level of performance. The outcome of this study may also inform recently suggested neurobiological accounts about the temporal dynamics of reward processing.


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