Functional brain activation during cognitive and emotional processing in young and old adults
Ongoing work includes analyses of two previously collected large functional magnetic resonance imaging (fMRI) datasets. The neural correlates of age-related differences in cognition and emotion are investigated in these analyses. In both projects, genotyping has also been performed, which makes it possible to link genetic information to brain function and structure and to behavioral data. Our four main projects are:
a. In a first study we aimed to examine age-differences in encoding and retrieval of emotional and non-emotional information across different retention intervals (after five minutes, one week and three weeks). Key findings include observations of an increasing rate of false recognition of negative pictures after one and three weeks, and this effect was more pronounced in older adults. Moreover, after three weeks of retention, activity in the amygdala was seen in the older adults, suggesting a reactivation of automatic processes related to emotional information. Another important result found only in the young adults is a reduction of medial temporal lobe engagement (and especially the hippocampus) over time for neutral items, but an increase in or stable activity for emotional items over time1.
b. Thirty young and thirty older adults have been scanned using cognitive and emotional fMRI-protocols, and analyses are currently underway. We found that activity in select regions of the prefrontal cortex may reflect greater affective processing when viewing happy than neutral or angry faces2. Greater activity in yet other regions may reflect more cognitive control involved in decoding and/or regulating negative emotions associated with neutral or angry (rather than happy), and older (rather than young) faces.
c. This study uses a cognitive interference task to investigate functional differences in activity patterns associated with interference resolution and their behavioral implications in young and older adults. Findings suggest that age-related structural brain changes contribute to reductions in efficient recruitment of key brain regions involved in interference control, which triggers a unique neural network facilitating conflict resolution in elderly people (work in progress). In addition to activation tasks using functional MRI, resting state fMRI and DTI data were collected.
d. Another ongoing project includes the study of the structural connectivity of functional networks (such as the default mode network, activated in the absence of any goal-directed external task; or the fronto-parietal attention network). Resting-state fMRI data will be used to identify the exact location of the networks’ nodes, marking the starting points of the white matter tracts whose structural properties will be calculated using tractography on the DTI data. The effects of age on networks’ structural properties will be studied, as well the relationships between the structural properties and cognitive data collected outside the scanner (offline tasks).
- Kalpouzos G, Fischer H, Rieckmann A, MacDonald SW, Bäckman L. Impact of negative emotion on the neural correlates of long-term recognition in younger and older adults. Front Integr Neurosci 2012; 6:74.
- Ebner NC, Johnson MK, Fischer H. Neural mechanisms of reading facial emotions in young and older adults. Front Psychol 2012; 3:223.