Virve Vuontela

Working Memory and Sleep in 6- to 13-Year-Old Schoolchildren

OBJECTIVE To study the associations between sleep quality/quantity and performance in auditory/visual working memory tasks of different load levels. METHOD Sixty schoolchildren aged 6 to 13 years from normal school classes voluntarily participated. Actigraphy measurement was done during a typical school week for 72 consecutive hours. It was timed together with the working memory experiments to obtain information on childrens sleep during that period. The n-back task paradigm was used to examine auditory and visual working memory functions. RESULTS Lower sleep efficiency and longer sleep latency were associated with a higher percentage of incorrect responses in working memory tasks at all memory load levels (partial correlations, controlling for age, all p values < .05, except in visual 0-back and auditive 2-back tasks); shorter sleep duration was associated with performing tasks at the highest load level only (partial correlations, controlling for age,p < .05). Also in general linear models (controlling for age, gender, and socioeconomic status), sleep efficiency (F = 11.706, p = .050) and latency (F = 3.588, p = .034) were significantly associated with the mean incorrect response rate in auditory working memory tasks. CONCLUSIONS Sleep quality and quantity affect performance of working memory tasks in school-age children. In children with learning difficulties the possibility of underlying sleep problems should be excluded.

Working memory, psychiatric symptoms, and academic performance at school

Previous studies of the relationship among working memory function, academic performance, and behavior in children have focused mainly on clinical populations. In the present study, the associations of the performance in audio- and visuospatial working memory tasks to teacher reported academic achievement and psychiatric symptoms were evaluated in a sample of fifty-five 6-13-year-old school children. Working memory function was measured by visual and auditory n-back tasks. Information on incorrect responses, reaction times, and multiple and missed responses were collected during the tasks. The childrens academic performance and behavioral and emotional status were evaluated by the Teacher Report Form. The results showed that good spatial working memory performance was associated with academic success at school. Children with low working memory performance, especially audiospatial memory, were reported to have more academic and attentional/behavioral difficulties at school than children with good working memory performance. An increased number of multiple and missed responses in the auditory and visual tasks was associated with teacher reported attentional/behavioral problems and in visual tasks with teacher reported anxiety/depressive symptoms. The results suggest that working memory deficits may underlie some learning difficulties and behavioral problems related to impulsivity, difficulties in concentration, and hyperactivity. On the other hand, it is possible that anxiety/depressive symptoms affect working memory function, as well as the ability to concentrate, leading to a lower level of academic performance at school.

Selective interference reveals dissociation between memory for location and colour

The aim was to study whether there is indication of a dissociation in processing of visuospatial and colour information in working memory in humans. Experimental subjects performed visuospatial and colour n-back tasks with and without visuospatial and colour distractive stimuli presented in the middle of the delay period to specifically affect mnemonic processing of task-related information. In the high memory-load condition, the visuospatial, but not the colour, task was selectively disrupted by visuospatial but not colour distractors. When subvocal rehearsal of the memoranda in the colour task was prevented by articulatory suppression; colour task performance was also selectively disrupted by distractors qualitatively similar to the memoranda. The results support the suggestion that visual working memory for location is processed separate from that for colour.

Brain activation and deactivation during location and color working memory tasks in 11-13-year-old children.

Using functional magnetic resonance imaging (fMRI) and n-back tasks we investigated whether, in 11-13-year-old children, spatial (location) and nonspatial (color) information is differentially processed during visual attention (0-back) and working memory (WM) (2-back) tasks and whether such cognitive task performance, compared to a resting state, results in regional deactivation. The location 0-back task, compared to the color 0-back task, activated segregated areas in the frontal, parietal and occipital cortices whereas no differentially activated voxels were obtained when location and color 2-back tasks were directly contrasted. Several midline cortical areas were less active during 0- and 2-back task performance than resting state. The task-induced deactivation increased with task difficulty as demonstrated by larger deactivation during 2-back than 0-back tasks. The results suggest that, in 11-13-year-old children, the visual attentional network is differently recruited by spatial and nonspatial information processing, but the functional organization of cortical activation in WM in this age group is not based on the type of information processed. Furthermore, 11-13-year-old children exhibited a similar pattern of cortical deactivation that has been reported in adults during cognitive task performance compared to a resting state.

Processing of auditory and visual location information in the monkey prefrontal cortex

Visuospatial working memory mechanisms have been studied extensively at single cell level in the dorsolateral prefrontal cortex (PFCd) in nonhuman primates. Despite the importance of short-term memory of sound location for behavioral orientation, there are only a few studies on auditory spatial working memory. The purpose of this study was to investigate neuronal mechanisms underlying working memory processing of auditory and visual location information at single cell level in the PFCd. Neuronal activity was recorded in monkeys performing a delayed matching-to-sample task (DMTS). The location of a visual or auditory stimulus was used as a memorandum. The majority of the neurons that were activated during presentation of the cue memorandum were selective either for visual or auditory spatial information. A small group of cue related bimodal neurons were sensitive to the location of the cue regardless of whether the stimulus was visual or auditory, suggesting modality independent processing of spatial information at cellular level in the PFCd. Most neurons that were activated during the delay period were modality specific, responding either during visual or auditory trials. All bimodal delay related neurons that responded during both visual and auditory trials were spatially nonselective. The results of the present study suggest that in addition to the modality specific parallel mechanism, working memory of auditory and visual space also involves modality independent processing at cellular level in the PFCd.

Brain activity during divided and selective attention to auditory and visual sentence comprehension tasks

Using functional magnetic resonance imaging (fMRI), we measured brain activity of human participants while they performed a sentence congruence judgment task in either the visual or auditory modality separately, or in both modalities simultaneously. Significant performance decrements were observed when attention was divided between the two modalities compared with when one modality was selectively attended. Compared with selective attention (i.e., single tasking), divided attention (i.e., dual-tasking) did not recruit additional cortical regions, but resulted in increased activity in medial and lateral frontal regions which were also activated by the component tasks when performed separately. Areas involved in semantic language processing were revealed predominantly in the left lateral prefrontal cortex by contrasting incongruent with congruent sentences. These areas also showed significant activity increases during divided attention in relation to selective attention. In the sensory cortices, no crossmodal inhibition was observed during divided attention when compared with selective attention to one modality. Our results suggest that the observed performance decrements during dual-tasking are due to interference of the two tasks because they utilize the same part of the cortex. Moreover, semantic dual-tasking did not appear to recruit additional brain areas in comparison with single tasking, and no crossmodal inhibition was observed during intermodal divided attention.

Regulation of brain activity in the fusiform face and parahippocampal place areas in 7―11-year-old children

Developmental studies have demonstrated that cognitive processes such as attention, suppression of interference and memory develop throughout childhood and adolescence. However, little is currently known about the development of top-down control mechanisms and their influence on cognitive performance. In the present study, we used functional magnetic resonance imaging to investigate modulation of activity in the ventral visual cortex in healthy 7-11-year-old children and young adults. The participants performed tasks that required attention to either face (Fs task) or scene (Sf task) images while trying to ignore distracting scene or face images, respectively. A face-selective area in the fusiform gyrus (fusiform face area, FFA) and an area responding preferentially to scene images in the parahippocampal gyrus (parahippocampal place area, PPA) were defined using functional localizers. Children responded slower and less accurately in the tasks than adults. In children, the right FFA was less selective to face images and regulation of activity between the Fs and Sf tasks was weaker compared to adults. In the PPA, selectivity to scenes and regulation of activity, there according to the task demands were comparable between children and adults. During the tasks, children activated prefrontal cortical areas including the middle (MFG) and superior (SFG) frontal gyrus more than adults. Functional connectivity between the right FFA and left MFG was stronger in adults than children in the Fs task. Children, on the other hand, had stronger functional connectivity than adults in the Sf task between the right FFA and right PPA and between right MFG and medial SFG. There were no group differences in the functional connectivity between the PPA and the prefrontal cortex (PFC). Together the results suggest that, in 7-11-year-old children, the FFA is still immature, whereas the selectivity to scenes and regulation of activity in the PPA is comparable to adults. The results also indicated functional immaturity of the PFC in children compared to adults and weaker connectivity between the PFC and the rFFA, explaining the weaker regulation of activity in the rFFA between the Fs and Sf tasks.

Gaming is related to enhanced working memory performance and task-related cortical activity

Gaming experience has been suggested to lead to performance enhancements in a wide variety of working memory tasks. Previous studies have, however, mostly focused on adult expert gamers and have not included measurements of both behavioral performance and brain activity. In the current study, 167 adolescents and young adults (aged 13-24 years) with different amounts of gaming experience performed an n-back working memory task with vowels, with the sensory modality of the vowel stream switching between audition and vision at random intervals. We studied the relationship between self-reported daily gaming activity, working memory (n-back) task performance and related brain activity measured using functional magnetic resonance imaging (fMRI). The results revealed that the extent of daily gaming activity was related to enhancements in both performance accuracy and speed during the most demanding (2-back) level of the working memory task. This improved working memory performance was accompanied by enhanced recruitment of a fronto-parietal cortical network, especially the dorsolateral prefrontal cortex. In contrast, during the less demanding (1-back) level of the task, gaming was associated with decreased activity in the same cortical regions. Our results suggest that a greater degree of daily gaming experience is associated with better working memory functioning and task difficulty-dependent modulation in fronto-parietal brain activity already in adolescence and even when non-expert gamers are studied. The direction of causality within this association cannot be inferred with certainty due to the correlational nature of the current study.

Attention and Working Memory in Adolescents with Autism Spectrum Disorder: A Functional MRI Study

Abstract The present study examined attention and memory load-dependent differences in the brain activation and deactivation patterns between adolescents with autism spectrum disorders (ASDs) and typically developing (TD) controls using functional magnetic resonance imaging. Attentional (0-back) and working memory (WM; 2-back) processing and load differences (0 vs. 2-back) were analysed. WM-related areas activated and default mode network deactivated normally in ASDs as a function of task load. ASDs performed the attentional 0-back task similarly to TD controls but showed increased deactivation in cerebellum and right temporal cortical areas and weaker activation in other cerebellar areas. Increasing task load resulted in multiple responses in ASDs compared to TD and in inadequate modulation of brain activity in right insula, primary somatosensory, motor and auditory cortices. The changes during attentional task may reflect compensatory mechanisms enabling normal behavioral performance. The inadequate memory load-dependent modulation of activity suggests diminished compensatory potential in ASD.

Responsiveness and functional connectivity of the scene-sensitive retrosplenial complex in 7-11-year-old children

Brain imaging studies have identified two cortical areas, the parahippocampal place area (PPA) and the retrosplenial complex (RSC), that respond preferentially to the viewing of scenes. Contrary to the PPA, little is known about the functional maturation and cognitive control of the RSC. Here we used functional magnetic resonance imaging and tasks that required attention to scene (or face) images and suppression of face (or scene) images, respectively, to investigate task-dependent modulation of activity in the RSC and whole-brain functional connectivity (FC) of this area in 7-11-year-old children and young adults. We compared responsiveness of the RSC with that of the PPA. The RSC was selectively activated by scene images in both groups, albeit less than the PPA. Children modulated activity between the tasks similarly in the RSC and PPA, and to the same extent as adults in PPA, whereas adults modulated activity in the RSC less than in PPA. In children, the whole brain FC of the RSC was stronger in the Sf than Fs task between the left RSC and right fusiform gyrus. The between groups comparison suggested stronger FC in children than adults in the Sf task between the right RSC and the left inferior parietal lobule and intraparietal sulcus. Together the results suggest that the function of the RSC and the related networks undergo dynamic changes over the development from 7-11-year-old children to adulthood.