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EN
The performance of semantic verbal fluency task is considered as an indicator of semantic memory and linguistic competence. The neural mechanisms of semantic memory are still discussed. Aim. In our study, brain activation associated with the performance (silent) in two tasks of verbal fluency (living: Animals, non-living: Vehicles) was described and compared. Brain activation was measured with functional magnetic resonance (fMRI) during a block schema tasks in 35 healthy individuals. Results. Brain activation during tasks performance compared to baseline condition involved many brain areas, especially in the left brain hemisphere and in the right cerebellum hemisphere. There were also found the differences in brain activation between non-living and living tasks; higher activation was observed in the fusiform gyri, in the hippocampus and in the parahipoccampal gyri. Conclusions. The data indicates that these tasks, despite of similar formal properties, are associated with partly different cognitive and neural mechanisms.
PL
Wykonanie zadań semantycznej fluencji słownej uznawane jest za wskaźnik stanu pamięci semantycznej i kompetencji językowych. Dyskusja na temat neuronalnych mechanizmów wiedzy semantycznej jest ciągle obecna w literaturze. Cel. W badaniach własnych opisano i porównano aktywacje mózgowe towarzyszące wykonaniu 2 zadań (ożywione: zwierzęta, nieożywione: pojazdy). Badania zrealizowano w schemacie blokowym z zastosowaniem funkcjonalnego rezonansu magnetycznego (fMRI). Uczestnikami były osoby zdrowe (N=35). Wyniki. Aktywność mózgu podczas generowania nazw obiektów z każdej kategorii w porównaniu do warunków kontrolnych dotyczyła głównie lewej półkuli mózgu i prawej półkuli móżdżku. Odnotowano także częściowe zróżnicowanie poziomu aktywacji podczas sekwencji funkcjonalnych: wymienianiu nazw obiektów nieożywionych w porównaniu do ożywionych towarzyszy wyższa aktywacja m.in. zakrętów wrzecionowatych, hipokampa i zakrętów przyhipokampalnych. Wnioski. Dane wskazują na to, że zadania te, mimo podobnych wymagań formalnych (rzeczowniki) angażują częściowo odmienne mechanizmy poznawczo-neuronalne.
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EN
Perceptual asymmetry is one of the most important characteristics of our visual functioning. We carefully reviewed the scientific literature in order to examine such asymmetries, separating them into two major categories: within-visual field asymmetries and between-visual field asymmetries. We explain these asymmetries in terms of perceptual aspects or tasks, thewhatof the asymmetries; and in terms of underlying mechanisms, thewhyof the asymmetries. The within-visual field asymmetries are fundamental to orientation, motion direction, and spatial frequency processing. The between-visual field asymmetries have been reported for a wide range of perceptual phenomena. The foveal dominance over the periphery, in particular, has been prominent for visual acuity, contrast sensitivity, and colour discrimination. This also holds true for object or face recognition and reading performance. The upper-lower visual field asymmetries in favour of the lower have been demonstrated for temporal and contrast sensitivities, visual acuity, spatial resolution, orientation, hue and motion processing. In contrast, the upper field advantages have been seen in visual search, apparent size, and object recognition tasks. The left-right visual field asymmetries include the left field dominance in spatial (e.g., orientation) processing and the right field dominance in non-spatial (e.g., temporal) processing. The left field is also better at low spatial frequency or global and coordinate spatial processing, whereas the right field is better at high spatial frequency or local and categorical spatial processing. All these asymmetries have inborn neural/physiological origins, theprimary why, but can be also susceptible to visual experience, thecritical why(promotes or blocks the asymmetries by altering neural functions).
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