The role of regional heterogeneity in age-related differences in functional hemispheric asymmetry: an fMRI study
Heng et al (2017) examined age-related differences in functional hemispheric asymmetry using functional magnetic resonance imaging (FMRI). The study used a Japanese rhyming task and a line judgment task to respectively measure language and visuospatial processing in young (20’s) and older adults (60’s). Findings indicated that both young and older adults were equally as accurate in both tasks, however, the older adults required more time to complete each task.
Further, authors found that for the Japanese rhyming task, there was an over-activation in the dorsal inferior frontal gyrus (BA 44) (specialized in phonological processing, which is the main type of language processing required for the Japanese rhyming task) in older adults and was related to better performance. This indicates that older adults recruited additional regions in BA 44 to help compensate and maintain similar behavioural performance similar to young adults in phonological processing. However, this effect was seen only when the Japanese rhyming task was contrasted against the fixation condition* and not the line judgment condition**. Thus, these findings have to be considered together with general age-related cognitive processes.
*The contrast of rhyming condition and fixation condition is not a perfect indicator for language processing because it also reflects general cognitive processes.
** The line judgment condition functions as a baseline for the rhyming task as it involves minimal verbal processes.
Functional Connectivity and Perceived Stress In Men and Women
A recent article published by Archer et al (2017) observed the connectivity between brain regions and perceived stress in men and women. Twenty-two women and twenty-four men completed questionnaires to indicate how stressed they have felt over the last month. They then completed a working-memory task and an inhibition task whilst undergoing functional Magnetic Resonance Imaging (FMRI). Findings indicate that in women higher levels of stress were related to increased functional connectivity within the limbic region, (i.e. middle cingulate, anterior cingulate cortex and the hippocampus) during tasks and at rest. These areas of the brain are heavily involved with emotion and affective processing. Similarly, stress was related to greater functional connectivity activations in the limbic regions during tasks in male participants, but was not associated with any changes in neural processing at rest. The findings support past research suggesting women employ emotion focused coping skills when stressed and challenges existing ideas that men are more reward focused when stressed.
Link to article : Archer, J. A., Lee, A., Qiu, A., & Chen, S. H. A. (2017). Functional connectivity of resting-state, working memory and inhibition networks in perceived stress. Neurobiology of Stress.
The above figure adapted from Archer et al (2017) illustrates the connectivity map for a) women, b) men and their resting-state and task dependent functional connectivity. Red = positive correlation and Blue = negative correlation. Yellow numbers indicate slice in MNI space. Voxel: p < 0.001, cluster: p < 0.05FWE. ACC = anterior cingulate cortex.