Browsing by Subject "jaettu tarkkaavaisuus"

The aim of this study is to examine the development of selective and divided attention in adolescence using functional magnetic resonance imaging (fMRI) and behavioral measures. Although the prefrontal cortex, a key area for attention and cognitive control, is thought to mature well into adulthood, few studies have examined the development of attention in adolescents and young adults. No fMRI studies have been conducted on the development of divided attention. In this study, development was examined both cross-sectionally and longitudinally to also assess the possible differences in the results they produced, as nearly all previous studies have been cross-sectional. Brain activity was measured from 103 participants aged 13–22 who were divided into three age cohorts. The youngest two cohorts were measured again after 1.5 years for the longitudinal study. While in the scanner, participants performed a sentence congruence task where they were instructed either to attend to only the speech or text stimulus or divide their attention between both modalities simultaneously. The cross-sectional results showed improvement in task performance between the youngest cohort (13– 14y.) and the older cohorts in both selective and divided attention tasks. No difference was found between the older two cohorts (16–17y. and 20–22y.) However, the longitudinal results did not indicate clear performance improvement with age in either task type. According to the longitudinal fMRI results from age 13–14 to 15–16, in the selective attention task brain activity decreased mainly in the medial prefrontal area and activity increased slightly in parietal regions. In the divided attention task, the decreased prefrontal activity was more lateral. From age 16–17 to 18– 19, increased activity in motor regions and precuneus was found in both tasks. In general, the effects were very subtle, possibly due to a short measurement interval and relatively small cohort sizes. The cross-sectional results indicated quite a different pattern of change in brain activity, concentrated on temporal areas. This difference in results emphasizes the importance of conducting longitudinal developmental studies in the future. Although the effects were not large, the longitudinal fMRI results were in line with some previous findings that prefrontal areas are recruited less with age, so that activity in more posterior task-related areas increases. The current results suggest that some fine-tuning of the attention and cognitive control-related network still occurs from adolescence to early adulthood, as the prefrontal cortex and its connections mature.