A meaningful interaction with our environment relies on the ability to focus on relevant sensory input and to ignore irrelevant information, i.e. top-down control and attention processes are employed to select from competing stimuli following internal goals. In this, the demands for the recruitment of top-down control processes depend on the relative perceptual salience of the competing stimuli. In the present functional magnetic resonance imaging (fMRI) study, we investigated the recruitment of top-down control processes in response to varying degrees of control demands in the auditory modality. For this purpose, we tested 20 male and 20 female subjects with a dichotic listening paradigm, in which the relative perceptual salience of two simultaneously presented stimuli was systematically manipulated by varying the inter-aural intensity difference (IID) and asking the subjects to selectively attend to either ear. The analysis showed that the interaction between IID and attentional direction involves two networks in the brain. A fronto-parietal network, including the pre-supplementary motor area, anterior cingulate cortex, inferior frontal junction, insula and inferior parietal lobe, was recruited during cognitively demanding conditions and can thus be seen as a top-down cognitive control network. In contrast, a second network including the superior temporal and the post-central gyri was engaged under conditions with low cognitive control demands. These findings demonstrate how cognitive control is achieved through the interplay of distinct brain networks, with their differential engagement determined as a function of the level of competition between the sensory stimuli. 相似文献
Studies investigating orthographic similarity effects in semantic tasks have produced inconsistent results. The authors investigated orthographic similarity effects in animacy decision and in contrast with previous studies, they took semantic congruency into account. In Experiments 1 and 2, performance to a target (cat) was better if a previously studied neighbor (rat) was congruent (i.e., belonged to the same animate-inanimate category) than it was if it was incongruent (e.g., mat). In Experiments 3 and 4, performance was better for targets with more preexisting congruent neighbors than for targets with more preexisting incongruent neighbors. These results demonstrate that orthographic similarity effects in semantic categorization are conditional on semantic congruency. This strongly suggests that semantic information becomes available before orthographic processing has been completed. 相似文献
Numerous studies have focused on the diversity of audiovisual integration between younger and older adults. However, consecutive trends in audiovisual integration throughout life are still unclear. In the present study, to clarify audiovisual integration characteristics in middle-aged adults, we instructed younger and middle-aged adults to conduct an auditory/visual stimuli discrimination experiment. Randomized streams of unimodal auditory (A), unimodal visual (V) or audiovisual stimuli were presented on the left or right hemispace of the central fixation point, and subjects were instructed to respond to the target stimuli rapidly and accurately. Our results demonstrated that the responses of middle-aged adults to all unimodal and bimodal stimuli were significantly slower than those of younger adults (p < 0.05). Audiovisual integration was markedly delayed (onset time 360 ms) and weaker (peak 3.97%) in middle-aged adults than in younger adults (onset time 260 ms, peak 11.86%). The results suggested that audiovisual integration was attenuated in middle-aged adults and further confirmed age-related decline in information processing. 相似文献
The article considers the potential of intergenerational encounters and family and social ties for alleviating loneliness and promoting older adults’ wellbeing. Loneliness has been widely recognized as one of the factors that are most deeply and pervasively detrimental to older adults’ wellbeing. We combine theoretical reflections with a comparative study of older adults in Denmark and China. Both countries have to deal with an aging population and growing number of cases of isolation and loneliness in an increasingly individualized society. They differ, however, with regard to how far they have developed a system of institutionalized care, as well as with regard to their culture-specific views of family life and parent-child relationships. We apply the notions of filial piety, known from Confucian philosophy but often misinterpreted as conservative and conformist, and generativity, to qualitative studies of older adults in Denmark and China. The great potential of intergenerational ties is confirmed. Our study also shows that filial piety is still highly valued, in both China and Denmark, and can be maintained even in a highly individualized society. There is, however, considerable uncertainty among both older adults and their younger relatives as to what is required and what can be expected; realism, and an emphasis on the quality, rather than the quantity of interaction, may be sensible coping strategies, but can also lead to unnecessary acquiescence and self-abnegation. Our study also serves to distinguish different aspects and effects on wellbeing of intergenerational relationships.
Exposure to an enriched environment (EE) has been shown to induce cortical plasticity. Considerable amount of research is focused on the effects of EE in the hippocampus; however, effects of EE on other brain regions and the mechanisms involved are not well known. To investigate this, we induced cortical plasticity by placing mice in an EE for one month and measured the effects of EE in the anterior cingulate cortex (ACC). Here, we show that EE enhanced the expression of the plasticity gene, egr-1, in the ACC of EE animals accompanied by enhanced cingulate long-term potentiation (LTP) and decreased cingulate long-term depression (LTD). The increased NMDA receptor NR2B/NR2A subunits current ratio is associated with the plasticity seen in the ACC while total protein levels remain unchanged. Furthermore, behavioral experiments show that these mice exposed to EE demonstrate enhanced responses to acute and long-term inflammation. Our findings suggest that exposure to EE alters physiological properties within the ACC which results in enhanced responses to inflammation. 相似文献
I first argue why Stanley and Williamson fail to eliminate the distinction between knowledge-that and knowledge-how. Then I argue that knowledge-how consists in a special kind of ways of thinking of ways of engaging in actions. So the distinction between knowledge-that and knowledge-how is twofold: the objects of knowledge-that and knowledge-how are different; the ways in which we entertain the object of knowledge are also distinct when we have knowledge-that and knowledge-how. At the end, I consider two recent intellectualist efforts on knowledge-how and show why they fail. 相似文献