In dynamic environments, a central task of the attentional system is to keep track of objects changing their spatial location over time. In some instances, it is sufficient to track only the spatial locations of moving objects (i.e., multiple object tracking; MOT). In other instances, however, it is also important to maintain distinct identities of moving objects (i.e., multiple identity tracking; MIT). Despite previous research, it is not clear whether MOT and MIT performance emerge from the same tracking mechanism. In the present report, we study gaze coherence (i.e., the extent to which participants repeat their gaze behaviour when tracking the same object locations twice) across repeated MOT and MIT trials. We observed more substantial gaze coherence in repeated MOT trials compared to the repeated MIT trials or mixed MOT-MIT trial pairs. A subsequent simulation study suggests that MOT is based more on a grouping mechanism than MIT, whereas MIT is based more on a target-jumping mechanism than MOT. It thus appears unlikely that MOT and MIT emerge from the same basic tracking mechanism.

• MeSH
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• oční fixace fyziologie   MeSH
• pozornost * fyziologie   MeSH
• vnímání pohybu * fyziologie   MeSH
• vnímání prostoru fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Contrary to other tasks (free viewing, recognition, visual search), participants often fail to recognize repetition of trials in multiple object tracking (MOT). This study examines the intra- and interindividual variability of eye movements in repeated MOT trials along with the adherence of eye movements to the previously described strategies. I collected eye movement data from 20 subjects during 64 MOT trials at slow speed (5°/s). Half of the trials were repeated four times, and the remaining trials were unique. I measured the variability of eye-movement patterns during repeated trials using normalized scanpath saliency extended to the temporal domain. People tended to make similar eye movements during repeated presentations (with no or vague feeling of repetition) and the interindividual similarity remained at the same level over time. Several strategies (centroid strategy and its variants) were compared with data and they accounted for 48.8% to 54.3% of eye-movement variability, which was less then variability explained by other peoples' eye movements (68.6%). The results show that the observed intra- and interindividual similarity of eye movements is only partly explained by the current models.

• MeSH
• lidé MeSH
• mladý dospělý MeSH
• sakadické oční pohyby fyziologie   MeSH
• světelná stimulace MeSH
• vnímání prostoru fyziologie   MeSH
• vnímání tvaru fyziologie   MeSH
• Check Tag
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

In everyday life, we often view objects through a limited aperture (e.g., soccer players on TV or cars slipping into our blind spot on a busy road), where objects often move out of view and reappear in a different place later. We modelled this situation in a series of multiple object tracking (MOT) experiments, in which we introduced a cover on the edges of the observed area and manipulated its width. This method introduced systematic occlusions, which were longer than those used in previous MOT studies. Experiment 1 (N = 50) showed that tracking under such conditions is possible, although difficult. An item-level analysis confirmed that people made more errors in targets that were covered longer and more often. In Experiment 2 (N = 50), we manipulated the tracking workload and found that the participants were less affected by the cover when the tracking load was low. In Experiment 3 (N = 50), we asked the participants to keep track of the objects' identities (multiple identity tracking [MIT]). Although MIT is subjectively more demanding, memorising identities improved performance in the most difficult cover conditions. Contrary to previous reports, we also found that even partial occlusions negatively affected tracking.

• MeSH
• lidé MeSH
• pozornost * MeSH
• vnímání pohybu * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

In everyday life, people often need to track moving objects. Recently, a topic of discussion has been whether people rely solely on the locations of tracked objects, or take their directions into account in multiple object tracking (MOT). In the current paper, we pose a related question: do people utilise extrapolation in their gaze behaviour, or, in more practical terms, should the mathematical models of gaze behaviour in an MOT task be based on objects' current, past or anticipated positions? We used a data-driven approach with no a priori assumption about the underlying gaze model. We repeatedly presented the same MOT trials forward and backward and collected gaze data. After reversing the data from the backward trials, we gradually tested different time adjustments to find the local maximum of similarity. In a series of four experiments, we showed that the gaze position lagged by approximately 110 ms behind the scene content. We observed the lag in all subjects (Experiment 1). We further experimented to determine whether tracking workload or predictability of movements affect the size of the lag. Low workload led only to a small non-significant shortening of the lag (Experiment 2). Impairing the predictability of objects' trajectories increased the lag (Experiments 3a and 3b). We tested our observations with predictions of a centroid model: we observed a better fit for a model based on the locations of objects 110 ms earlier. We conclude that mathematical models of gaze behaviour in MOT should account for the lags.

• MeSH
• časové faktory MeSH
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• oční fixace fyziologie   MeSH
• pozornost fyziologie   MeSH
• psychologické modely * MeSH
• rozpoznávání obrazu fyziologie   MeSH
• vnímání pohybu fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Although the Multiple Object Tracking (MOT) task is a widely used experimental method for studying divided attention, tracking objects in the real world usually looks different. For example, in the real world, objects are usually clearly distinguishable from each other and also possess different movement patterns. One such case is tracking groups of creatures, such as tracking fish in an aquarium. We used movies of fish in an aquarium and measured general tracking performance in this task (Experiment 1). In Experiment 2, we compared tracking accuracy within-subjects in fish tracking, tracking typical MOT stimuli, and in a third condition using standard MOT uniform objects which possessed movement patterns similar to the real fish. This third condition was added to further examine the impact of different motion characteristics on tracking performance. Results within a Bayesian framework showed that tracking real fish shares similarities with tracking simple objects in a typical laboratory MOT task. Furthermore, we observed a close relationship between performance in both laboratory MOT tasks (typical and fish-like) and real fish tracking, suggesting that the commonly used laboratory MOT task possesses a good level of ecological validity.

• Publikační typ
• časopisecké články MeSH

We present a fast and robust approach to tracking the evolving shape of whole fluorescent cells in time-lapse series. The proposed tracking scheme involves two steps. First, coherence-enhancing diffusion filtering is applied on each frame to reduce the amount of noise and enhance flow-like structures. Second, the cell boundaries are detected by minimizing the Chan-Vese model in the fast level set-like and graph cut frameworks. To allow simultaneous tracking of multiple cells over time, both frameworks have been integrated with a topological prior exploiting the object indication function. The potential of the proposed tracking scheme and the advantages and disadvantages of both frameworks are demonstrated on 2-D and 3-D time-lapse series of rat adipose-derived mesenchymal stem cells and human lung squamous cell carcinoma cells, respectively.

• MeSH
• buněčné jádro chemie   MeSH
• buněčný tracking metody   MeSH
• fluorescenční mikroskopie metody   MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• mezenchymální kmenové buňky cytologie   MeSH
• nádorové buněčné linie MeSH
• počítačové zpracování obrazu metody   MeSH
• tvar buňky fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Úvod: Selektivní dorzální rizotomie (SDR) představuje standardní terapeutickou metodu léčby spasticity. Kromě snížení spasticity dolních končetin bylo v literatuře opakovaně popisováno i zlepšení motorických dovedností na horních končetinách, zlepšení řeči a očních pohybů. Cíl: Cílem této studie bylo objektivizovat zlepšení fonace a sledovacích očních pohybů. Metodika: Osm pacientů podstoupilo vyšetření videookulografií a 11 akustickou analýzu řeči. Měřenými parametry byly odchylka od základní frekvence, shimmer, jitter a fonační index v akustické analýze řeči a korelační koeficient horizontálního stimulu při videookulografii. Výsledky: Sedm z 11 pacientů vykazovali zlepšení v akustických parametrech, u čtyř subjektů došlo ke zlepšení sledovacích očních pohybů. Závěr: Zlepšení fonace a sledovacích očních pohybů po selektivní dorzální rizotomii bylo objektivizováno vyšetřovacími metodami. Popsané suprasegmentální efekty SDR lze vysvětlit možným snížením odpovědi patologického polysynaptického reflexu vzniklé deaferentací po selektivní dorzální rizotomii.

Backgrounds: Selective dorsal rhizotomy (SDR) represents a standard therapeutic technique for the treatment of spasticity. Besides reducing spasticity of the lower limbs, an improvement in motor skills of the upper limbs and an improvement in speech and eye movements have also been repeatedly documented in literature. Aim: The objective of this study was to objectify the improvement in phonation and eye tracking. Methods: Eight patients underwent videooculographic testing and 11 underwent acoustic speech analysis. The measured parameters were a deviation from basic frequency, shimmer, jitter and phonation index in the acoustic speech analysis and a correlation coefficient of the horizontal stimulus upon videooculography. Results: Seven of the eleven patients demonstrated an improvement in acoustic parameters; four subjects reported an improvement in eye tracking. Conclusion: Improvement in phonation and eye tracking following selective dorsal rhizotomy was objectified by testing techniques. The described suprasegmental effects of SDR can be explained by a possibly reduced response of the pathologic polysynaptic due to deafferentation, which developed following selective dorsal rhizotomy.

• MeSH
• audiovizuální záznam využití   MeSH
• dítě MeSH
• elektromyografie metody   využití   MeSH
• elektrookulografie metody   využití   MeSH
• financování organizované MeSH
• fonace MeSH
• laminektomie metody   využití   MeSH
• lidé MeSH
• neurochirurgické výkony metody   MeSH
• retrospektivní studie MeSH
• rizotomie metody   využití   MeSH
• statistika jako téma MeSH
• svalová spasticita diagnóza   terapie   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH

BACKGROUND AND OBJECTIVE: The geodesic ray-tracing method has shown its effectiveness for the reconstruction of fibers in white matter structure. Based on reasonable metrics on the spaces of the diffusion tensors, it can provide multiple solutions and get robust to noise and curvatures of fibers. The choice of the metric on the spaces of diffusion tensors has a significant impact on the outcome of this method. Our objective is to suggest metrics and modifications of the algorithms leading to more satisfactory results in the construction of white matter tracts as geodesics. METHODS: Starting with the DTI modality, we propose to rescale the initially chosen metric on the space of diffusion tensors to increase the geodetic cost in the isotropic regions. This change should be conformal in order to preserve the angles between crossing fibers. We also suggest to enhance the methods to be more robust to noise and to employ the fourth order tensor data in order to handle the fiber crossings properly. RESULTS: We propose a way to choose the appropriate conformal class of metrics where the metric gets scaled according to tensor anisotropy. We use the logistic functions, which are commonly used in statistics as cumulative distribution functions. To prevent deviation of geodesics from the actual paths, we propose a hybrid ray-tracing approach. Furthermore, we suggest how to employ diagonal projections of 4th order tensors to perform fiber tracking in crossing regions. CONCLUSIONS: The algorithms based on the newly suggested methods were succesfuly implemented, their performance was tested on both synthetic and real data, and compared to some of the previously known approaches.

• MeSH
• algoritmy MeSH
• anizotropie MeSH
• bílá hmota * diagnostické zobrazování   MeSH
• mozek diagnostické zobrazování   MeSH
• zobrazování difuzních tenzorů MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: An early diagnosis together with an accurate disease progression monitoring of multiple sclerosis is an important component of successful disease management. Prior studies have established that multiple sclerosis is correlated with speech discrepancies. Early research using objective acoustic measurements has discovered measurable dysarthria. METHOD: The objective was to determine the potential clinical utility of machine learning and deep learning/AI approaches for the aiding of diagnosis, biomarker extraction and progression monitoring of multiple sclerosis using speech recordings. A corpus of 65 MS-positive and 66 healthy individuals reading the same text aloud was used for targeted acoustic feature extraction utilizing automatic phoneme segmentation. A series of binary classification models was trained, tuned, and evaluated regarding their Accuracy and area-under-the-curve. RESULTS: The Random Forest model performed best, achieving an Accuracy of 0.82 on the validation dataset and an area-under-the-curve of 0.76 across 5 k-fold cycles on the training dataset. 5 out of 7 acoustic features were statistically significant. CONCLUSION: Machine learning and artificial intelligence in automatic analyses of voice recordings for aiding multiple sclerosis diagnosis and progression tracking seems promising. Further clinical validation of these methods and their mapping onto multiple sclerosis progression is needed, as well as a validating utility for English-speaking populations.

• MeSH
• lidé MeSH
• pilotní projekty MeSH
• řeč * MeSH
• roztroušená skleróza * MeSH
• strojové učení MeSH
• umělá inteligence MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Tento výzkum je zaměřen na vysvětlení sportovního výkonu z hlediska úhlu, rychlosti, časové a prostorové charakteristiky těžiště, polohy těla, končetin a tyče při přiblížení, vzletu a realizaci skoku o tyči žen. Kinematické parametry byly získány dvourozměrným analyzátorem Consport Motion Analysis System (CMAS). Bylo zahrnuto 19 juniorek, skokanek o tyči, se sportovním výkonem 408,1–490,5 cm (průměrný výsledek 431,2 cm). Z hlediska analýzy biomechanické pohybové aktivity považujeme za objektivnější výkonnostní kritérium (závislou proměnnou) maximální výšku těžiště, které bylo dosaženo při platných pokusech při skoku o tyči. Dvojrozměrnou (2-D) analýzou skupiny skokanek o tyči se zjistilo 76 nezá- vislých proměnných, které vstoupily do procesu multikorelační a regresní analýzy. Na úrovni prvního výkonnostního faktoru sportovní struktury jsme izolovali dva komplexní parametry: absolutní úchop a zvrat, čímž dokážeme vysvětlit závislou proměnnou maximální výšku těžiště na 100%. S uvedeným postupem jsme mohli na 2. úrovni oddělit sedm faktorů. Tři z parametrů horizontální rychlosti těžiště v okamžiku odletu, výška těžiště v okamžiku odletu a pracovní úhel při vzletu jsou vysvětlením absolutní proměnné úchopu. Další čtyři parametry vertikální rychlosti těžiště na konci tahu s otočením, výška těžiště v okamžiku ukončení zdvihu, doba trvání vzletu a úhel stoupání vysvětlují zvrat. Na úrovni 3. úrovně sportovní struktury je nalezeno dalších 14 faktorů. Tím se nám podařilo v tomto procesu snížit počet rozhodujících proměnných s jejich vzájemnými vztahy a hierarchií. Transparentní a zjednodušený model struktury sportovních výkonů ve skoku o tyči žen umožňuje trenérům a skokanům zlepšit technický trénink.

This research is oriented at explanation of sport performance by angle, speed, time and space characteristics of centre of gravity, positions of body, extremities and pole during approach, take-off and jump realization in female pole vault. Kinematic parameters were gained by two-dimension analyser Consport Motion Analysis System (CMAS). There are involved 19 female pole vault jumpers with sport performance 408.1–490.5 cm (average result 431.2 cm). From the point of biomechanical movement activity analyse we consider as a more objective performance criterion (dependent variable) maximal centre of gravity height that were reached at valid attempts by female pole vault jumpers. By twodimension (2-D) analyse of group of female pole vault jumpers there were revealed 76 independent variables that entered into process of multiple correlation and regression analysis. On 1st sport structure performance factor level we isolated two complex parameters absolute grip and standing over by which we can explain dependent variable maximal centre of gravity height on 100%. With stated proceeding we could separate seven factors on 2nd level. Three of the parameters horizontal speed of centre of gravity at moment of take-off end, centre of gravity height at moment of take-off end and operating angle during take-off are bound with explanation of absolute grip variable. Four others parameters vertical speed of centre of gravity at the end of pull with turn, centre of gravity height at moment of end of lifting, time duration of take-off and climb angle explain standing over. 14 more factors are found on 3rd sport structure performance level. Thus we succeeded in this process to reduce number of decisive variables with their mutual relationships and hierarchy. Transparent and simplified model of female pole vault sport performance structure enables to coaches and jumpers improve technical training.

• Klíčová slova
• těžiště v průběhu skoku,
• MeSH
• biomechanika * MeSH
• lehká atletika * statistika a číselné údaje   MeSH
• lidé MeSH
• pohybová aktivita MeSH
• statistika jako téma MeSH
• tělesná výkonnost MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH