An fMRI study of the numerical Stroop task in individuals with and without minimal cognitive impairment

Behaviourally, robust distance and congruity effects were observed in both groups and tasks. Imaging baseline conditions revealed stronger and more distributed activations in MCI patients relative to controls which could not be explained by the higher error rates committed by patients. Across tasks, conjunction analysis revealed highly significant activations in intra-parietal and prefrontal regions suggesting that both groups recruit comparable brain regions upon processing magnitude and interference, respectively. MCI patients exhibited stronger pre-/postcentral and thalamic activations, possibly reflecting more effortful response-selection processes or alternatively, deficient inhibitory control. Moreover, MCI patients exhibited additional activations in fronto-parietal (magnitude) and occipital/cerebellar (congruity) regions. To summarize, though MCI patients needed to recruit more distributed activation patterns conjunction analysis revealed common activation sites in response to magnitude processing and interference control.