Composite Measures of Brain Activation Predict Individual Differences in Behavioral Stroop Interference.

The goal of the current study was to interrogate aspects of the cascade-of-control model [Banich, M. T. Executive function: The search for an integrated account. Current Directions in Psychological Science, 18, 89-94, 2009; Banich, M. T. The Stroop effect occurs at multiple points along a cascade of control: Evidence from cognitive neuroscience approaches. Frontiers in Psychology, 10, 2164, 2019], a neurocognitive model that posits how portions of pFC interact in a cascade-like manner to overcome interference from task-irrelevant information, and to test whether it could be used to predict individual differences in cognitive control outside the scanner. Participants (n = 62) completed two fMRI Word-Picture Stroop tasks, one containing emotional stimuli and one containing non-emotional stimuli, as well as a behavioral out-of-scanner Color-Word Stroop task at each of two time points. In a departure from the traditional approach of using a single task contrast to index neural activation across all ROIs, the current study utilized specific ROI by contrast pairings selected based on the specific level of control hypothesized by the cascade-of-control model to occur within that region. In addition, data across both tasks and both time points were combined to create composite measures of neural activation and of behavior. Consistent with the cascade-of-control model, individual differences in brain activation for specific contrasts within each of the three ROIs were associated with behavioral interference on the standard Color-Word Stroop task. Testing of alternative models revealed that these brain-behavior relationships were specific to the theoretically driven ROI by contrast pairings. Furthermore, such relationships were not observed across single-task and single-time point measures, but instead emerged from the composite measures. These findings provide evidence that brain activation observed across multiple regions of frontal cortex, each of which likely exerts cognitive control in a differential manner, is capable of predicting individual differences in behavioral performance.

Topographical functional correlates of interindividual differences in executive functions in young healthy twins.

Executive functions (EF) are a set of higher-order cognitive abilities that enable goal-directed behavior by controlling lower-level operations. In the brain, those functions have been traditionally associated with activity in the Frontoparietal Network, but recent neuroimaging studies have challenged this view in favor of more widespread cortical involvement. In the present study, we aimed to explore whether the network that serves as critical hubs at rest, which we term network reliance, differentiate individuals as a function of their level of EF. Furthermore, we investigated whether such differences are driven by genetic as compared to environmental factors. For this purpose, resting-state functional magnetic resonance imaging data and the behavioral testing of 453 twins from the Colorado Longitudinal Twins Study were analyzed. Separate indices of EF performance were obtained according to a bifactor unity/diversity model, distinguishing between three independent components representing: Common EF, Shifting-specific and Updating-specific abilities. Through an approach of step-wise in silico network lesioning of the individual functional connectome, we show that interindividual differences in EF are associated with different dependencies on neural networks at rest. Furthermore, these patterns show evidence of mild heritability. Such findings add knowledge to the understanding of brain states at rest and their connection with human behavior, and how they might be shaped by genetic influences.

Changes to information in working memory depend on distinct removal operations.

Holding information in working memory is essential for cognition, but removing unwanted thoughts is equally important. Here we use multivariate pattern analyses of brain activity to demonstrate the successful manipulation and removal of information from working memory using different strategies including suppressing a specific thought, replacing a thought with a different one, and clearing the mind of all thought. These strategies are supported by distinct brain regions and have differential consequences for allowing new information to be encoded.

Common and specific dimensions of internalizing disorders are characterized by unique patterns of brain activity on a task of emotional cognitive control.

Alterations in neural systems underlying cognitive control are well-documented across individuals with various internalizing disorders. The current study examined how individual differences in underlying traits related to internalizing disorders influence brain activation, as assessed by fMRI, when cognitive control must be exerted to make a decision about the emotional valence (positive, negative) of a task-relevant word displayed concurrently with a task-irrelevant emotional face. Taking a bi-factor model approach, fifty-five middle-aged female participants were characterized on symptom level on a common internalizing latent factor representing shared symptoms across anxiety and depression, as well as on specific factors remaining after taking the common internalizing factor into account: low positive affect, anxious arousal, and anxious apprehension. Contrasting activation on trials requiring higher vs. lower control revealed that higher levels of the Common Internalizing factor are associated with less deactivation of regions of the default mode network. Higher levels of the Low Positive Affect-specific factor are associated with less differentiation in engagement of portions of the fronto-parietal control network, while higher levels of the Anxious Arousal-specific factor are associated with less of a differentiation in activation of the thalamus. No effects were observed for level of the Anxious Apprehension-specific factor. These results suggest that prior findings of alterations in default mode activity associated with depression may not be specific to depressive symptoms per se but may characterize internalizing symptoms more generally. In addition, they suggest that reduced engagement of cognitive control regions may be more associated with low positive affect than depressive symptoms more generally.

The role of conflict, feedback, and action comprehension in monitoring of action errors: Evidence for internal and external routes.

The mechanisms and brain regions underlying error monitoring in complex action are poorly understood, yet errors and impaired error correction in these tasks are hallmarks of apraxia, a common disorder associated with left hemisphere stroke. Accounts of monitoring of language posit an internal route by which production planning or competition between candidate representations provide predictive signals that monitoring is required to prevent error, and an external route in which output is monitored using the comprehension system. Abnormal reliance on the external route has been associated with damage to brain regions critical for sensory-motor transformation and a pattern of gradual error 'clean-up' called conduite d'approche (CD). Action pantomime data from 67 participants with left hemisphere stroke were consistent with versions of internal route theories positing that competition signals monitoring requirements. Support Vector Regression Lesion Symptom Mapping (SVR-LSM) showed that lesions in the inferior parietal, posterior temporal, and arcuate fasciculus/superior longitudinal fasciculus predicted action conduite d'approche, overlapping the regions previously observed in the language domain. A second experiment with 12 patients who produced substantial action CD assessed whether factors impacting the internal route (action production ability, competition) versus external route (vision of produced actions, action comprehension) influenced correction attempts. In these 'high CD' patients, vision of produced actions and integrity of gesture comprehension interacted to determine successful error correction, supporting external route theories. Viewed together, these and other data suggest that skilled actions are monitored both by an internal route in which conflict aids in detection and correction of errors during production planning, and an external route that detects mismatches between produced actions and stored knowledge of action appearance. The parallels between language and action monitoring mechanisms and neuroanatomical networks pave the way for further exploration of common and distinct processes across these domains.

Movement Imitation via an Abstract Trajectory Representation in Dorsal Premotor Cortex.

Humans are particularly good at copying novel and meaningless gestures. The mechanistic and anatomical basis for this specialized imitation ability remains largely unknown. One idea is that imitation occurs by matching body configurations. Here we propose an alternative route to imitation that depends on a body-independent representation of the trajectory path of the end-effector. We studied a group of patients with strokes in the left frontoparietal cortices. We found that they were equally impaired at imitating movement trajectories using the ipsilesional limb (i.e., the nonparetic side) that were cued either by an actor using their whole arm or just by a cursor, suggesting that body configuration information is not always critical for imitation and that a representation of abstract trajectory shape may suffice. In addition, imitation ability was uncorrelated to the ability to identify the trajectory shape, suggesting that imitation deficits were unlikely to arise from perceptual impairments. Finally, a lesion-symptom mapping analysis found that imitation deficits were associated with lesions in left dorsal premotor but not parietal cortex. Together, these findings suggest a novel body-independent route to imitation that relies on the ability to plan abstract movement trajectories within dorsal premotor cortex.SIGNIFICANCE STATEMENT The ability to imitate is critical for rapidly learning to produce new gestures and actions, but how the brain translates observed movements into motor commands is poorly understood. Examining the ability of patients with strokes affecting the left hemisphere revealed that meaningless gestures can be imitated by succinctly representing only the motion of the hand in space, rather than the posture of the entire arm. Moreover, performance deficits correlated with lesions in dorsal premotor cortex, an area not previously associated with impaired imitation of arm postures. These findings thus describe a novel route to imitation that may also be impaired in some patients with apraxia.

Individual differences in mixing costs relate to general executive functioning.

The ability to enact cognitive control under changing environmental demands is commonly studied using set-shifting paradigms. While the control processes required for task set reconfiguration (switch costs) have been studied extensively, less research has focused on the control required during task repetition in blocks containing multiple tasks as compared to those containing a single task (mixing costs). We investigated how individual differences in mixing costs related to other executive functions (EFs) in a large sample (N = 749) of young adults. Individual differences in mixing costs across three different set-shifting paradigms loaded significantly onto a mixing cost latent variable. This Mixing Cost factor moderately correlated with a Common EF factor capturing variance shared across nine EF tasks designed to tap response inhibition, working memory updating, and mental set-shifting. It did not correlate with Updating-Specific and Shifting-Specific factors. Results indicate that the additional cognitive control required during mixed-task block repeat trials relies on general executive processes, as well as unique abilities distinct from both set-shifting and working memory updating. (PsycINFO Database Record (c) 2019 APA, all rights reserved).