Factors influencing the role of cardiac autonomic regulation in the service of cognitive control.

Working from a model of neurovisceral integration, we examined whether adding response contingencies and motivational involvement would increase the need for cardiac autonomic regulation in maintaining effective cognitive control. Respiratory sinus arrhythmia (RSA) was recorded during variants of the Stroop color-word task. The Basic task involved "accepting" congruent items and "rejecting" words printed in incongruent colors (BLUE in red font); an added contingency involved rejecting a particular congruent word (e.g., RED in red font), or a congruent word repeated on an immediately subsequent trial. Motivation was increased by adding a financial incentive phase. Results indicate that pre-task RSA predicted accuracy best when response contingencies required the maintenance of a specific item in memory or on the Basic Stroop task when errors resulted in financial loss. Overall, RSA appeared to be most relevant to performance when the task encouraged a more proactive style of cognitive control, a control strategy thought to be more metabolically costly, and hence, more reliant on flexible cardiac autonomic regulation.

Cardiac workload and inhibitory control in younger and older adults.

Our goal was to investigate age differences in the role played by cardiovascular regulation in response control. We questioned whether pre-test respiratory sinus arrhythmia (RSA; an index of phasic vagal cardiac control) and/or rate pressure product (RPP; a measure of cardiac workload) were associated with error rate and/or error-related electrocortical responses (ERPs) during a Go/NoGo inhibitory control task across three levels of working memory load. ERPs, RSA and RPP were indirectly associated with performance in young adults. Within the older group, higher resting RPP was directly associated with NoGo errors at all levels of load, an association not seen in the younger group. Thus, for older adults, excessive hemodynamic demands at rest were more relevant than on-task electrocortical responses in the prediction of inhibitory control errors. These data support the relevance of autonomic regulation in understanding age-related change in higher-order neurocognitive function.

Age-related differences during simple working memory decisions: ERP indices of early recognition and compensation failure.

Imaging data has identified frontal cortical activation in older adults during simple recognition tasks that relates positively with performance and could, therefore, be considered compensatory. However, in a previous electrophysiological study involving a Sternberg task with proactive interference manipulations, we observed a frontal positive scalp potential between 400 and 500 ms that was unique to older adults and predictive of poorer performance. These results led us to ask whether unique frontal activation in older adults serves a compensatory role only during relatively simple tasks when stimulus familiarity provides an unambiguous basis for response selection. In the current study, we tested this hypothesis by having younger and older adults complete a verbal Sternberg task without interference manipulations. In younger adults, we observed an early posterior negativity (90-120 ms) that predicted performance accuracy. Older adults failed to show this early negativity but did produce the expected frontal positivity. However, the frontal positivity was again associated with poorer performance. These data support the view that younger adults are able to bias early target discrimination to benefit response selection whereas older adults rely on later controlled processes that are not always effective in buffering against normative age-related decline.