Age-related Increase in Activation of Effort-related Brain Areas During a Sustained Fatiguing Contraction.

Abstract

Fatiguing contractions result in an overall increase in activation of the motor cortical areas. Older adults activate additional, ipsilateral areas during a non-fatiguing motor task. The activity pattern in older adults during a fatiguing motor task is not well studied. PURPOSE: To examine the effects of age on brain activation during a sustained fatiguing contraction with the right index finger abductor. METHODS: Thirty subjects (age-range: 19-64 years) performed a fatiguing maximal force task with their right first dorsal interosseous (FDI) in a 3 Tesla MR scanner during which the blood oxygen level dependent (BOLD) signal was recorded. The age-related changes in brain activation were determined using a one-sample t-test with age square as a covariate. RESULTS: The left inferior and superior parietal lobe, left rolandic operculum, left precuneus, left middle occipital gyrus, right hippocampus, bilateral parahippocampal gyrus, bilateral middle temporal gyrus, bilateral fusiform gyrus, bilateral insula and bilateral middle cingulate cortex were significantly more active with age (t>3.41, p<0.001 uncorrected). CONCLUSION: There is an age-related increase in brain activation, including the activation of several structures ipsilateral to the contracting hand, during a sustained fatiguing contraction. Most areas are thought to be involved in sensory-motor integration, effort- or cost-benefit analysis.