The functional oculomotor network and saccadic cognitive control in healthy elders.

Decline in executive function is the most common age-associated cognitive deficit and may be a risk factor for neurodegenerative disease. The antisaccade (AS) task involves inhibition of a prepotent visuomotor response and is a well-validated executive function test in aging and neurodegeneration. We investigated the functional connectivity of the cortical oculomotor network during successful AS performance in healthy elders. Elevated BOLD activity in the right lateral frontal eye field (rlatFEF), a region linked to volume loss in individuals with impaired AS performance, was associated with worse AS performance and weaker network efficiency. In contrast, hub integrity of the right dorsolateral prefrontal cortex (rDLPFC) and anterior cingulate cortex (rACC) was associated with better AS performance. These data suggest that while several right lateral frontal regions are central nodes in the oculomotor network, the rlatFEF demonstrates early neural aberrations and the rDLPFC and rACC continue to support inhibitory cognitive control in healthy elders. We conclude that alterations in AS task functional connectivity, quantified as hub and network efficiency, may be clinically-relevant biomarkers of cognitive decline in executive functioning.

Antisaccade task reflects cortical involvement in mild cognitive impairment.

OBJECTIVE: The aims of this study were to examine executive dysfunction using an antisaccade (AS) task in normal elderly (NE) and patients with mild cognitive impairment (MCI) and Alzheimer disease (AD) as well as to evaluate the relationship between AS performance and cortical thinning within AD-associated regions. METHODS: We recorded eye movements in 182 subjects (NE: 118; MCI: 36; AD: 28) during an AS task. We also performed neuropsychological measures of executive function for comparison. Brain MRI scans were collected on most subjects, and cortical thickness was determined in 9 regions known to exhibit atrophy in AD dementia ("AD signature"). We investigated the relationships between AS and neuropsychological performance, as well as possible correlations between AS performance and cortical thickness. RESULTS: AS performance in MCI resembled that in NE; subjects with AD were impaired relative to both MCI and NE. In all subjects, AS performance correlated with neuropsychological measures of executive function, even after controlling for disease severity. In the subjects with MCI but not in NE, cortical thickness in frontoparietal AD signature regions correlated with AS performance. CONCLUSIONS: The AS task is a useful measure of executive function across the AD spectrum. In MCI, AS performance may reflect disease burden within cortical brain regions involved in oculomotor control; however, AS impairments in NE may have etiologies other than incipient AD.