Aging and inhibitory control of action: cortico-subthalamic connection strength predicts stopping performance.
Diffusion weighted imaging (DWI) studies in humans have shown that seniors exhibit reduced white matter integrity compared with young adults, with the most pronounced change occurring in frontal white matter. It is generally assumed that this structural deterioration underlies inhibitory control deficits in old age, but specific evidence from a structural neuroscience perspective is lacking. Cognitive action control is thought to rely on an interconnected network consisting of right inferior frontal cortex (r-IFC), pre-supplementary motor area (preSMA), and the subthalamic nucleus (STN). Here we performed probabilistic DWI tractography to delineate this cognitive control network and had the same individuals (20 young, 20 older adults) perform a task probing both response inhibition and action reprogramming. We hypothesized that structural integrity (fractional anisotropy) and connection strength within this network would be predictive of individual and age-related differences in task performance. We show that the integrity of r-IFC white matter is an age-independent predictor of stop-signal reaction time (SSRT). We further provide evidence that the integrity of white matter projecting to STN predicts both outright stopping (SSRT) and transient braking of response initiation to buy time for action reprogramming (stopping interference effects). These associations remain even after controlling for Go task performance, demonstrating specificity to the Stop component of this task. Finally, a multiple regression analysis reveals bilateral preSMA-STN tract strength as a significant predictor of SSRT in older adults. Our data link age-related decline in inhibitory control with structural decline of STN projections.
Movement Control and Neuroplasticity Research Group, Katholieke Universiteit Leuven, 3001 Leuven, Belgium. j.coxon@auckland.ac.nz
James P
JP
Coxon
Annouchka
A
Van Impe
Nicole
N
Wenderoth
Stephan P
SP
Swinnen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology / Q000502:physiology* / Q000523:psychology*; D016880:Anisotropy; D001931:Brain Mapping / Q000379:methods / Q000523:psychology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods / Q000523:psychology; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000502:physiology*; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology / Q000502:physiology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology / Q000502:physiology; D009434:Neural Pathways / Q000473:pathology / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D020531:Subthalamic Nucleus / Q000473:pathology / Q000502:physiology*