Intrinsic Fluctuations in Sustained Attention and Distractor Processing

Abstract

Although sustaining a moderate level of attention is critical in daily life, evidence suggests that attention is not deployed consistently, but rather fluctuates from moment to moment between optimal and suboptimal states. To better characterize these states in humans, the present study uses a gradual-onset continuous performance task with irrelevant background distractors to explore the relationship among behavioral fluctuations, brain activity, and, in particular, the processing of visual distractors. Using fMRI, we found that reaction time variability, a continuous measure of attentional instability, was positively correlated with activity in task-positive networks and negatively correlated with activity in the task-negative default mode network. We also observed greater processing of distractor images during more stable and less error prone "in the zone" epochs compared with suboptimal "out of the zone" epochs of the task. Overall, the data suggest that optimal states of attention are accomplished with more efficient and potentially less effortful recruitment of task-relevant resources, freeing remaining resources to process task irrelevant features of the environment.

Spontaneous default network activity reflects behavioral variability independent of mind-wandering

“…We focused on reaction time (RT) variability in the 30-s prerating period (except where indicated) because relative to shorter prerating time windows, we could use more samples to calculate RT metrics (23 trials) and acknowledge uncertainty in the duration of preprobe periods to which participants' thought-probe responses referred (but results from shorter prerating periods were largely similar; Table S2). For consistency with previous studies on the DMN and RT variability (19,20), we report our main analyses based on RT variance (absolute deviance from the mean) across trials preceding thought probes, but we also report results with RT coefficient of variation (CoV).…”

“…Here, we have shown that increased RT variability is associated with self-reports of greater off-task attention at both intra-and interindividual levels, yet decreased RT variability and off-task self-reports have separately been previously associated with increased DMN activity (9,10,12,19,20). To evaluate each of those relationships in our paradigm, we extracted mean activity level (percent signal change, %SC) in 30-s prerating periods from the DMN, defined from a network atlas developed in an independent, large cohort of subjects, and including gray matter in the medial prefrontal cortex, posterior cingulate cortex, lateral parietal areas, portions of the temporal lobe, and cerebellar A B C components (Fig.…”

“…Other networks besides the DMN could be involved in self-reportable attention and/or behavioral variability. Increased behavioral variability has previously been associated with higher activity in dorsal attention and salience networks (opposite to the DMN pattern) (19)(20)(21), and some but not all previous studies (35,36) have found increased mind-wandering associated with activity in the frontoparietal control network. Additionally, because our measurements occurred in tandem with sensorimotor processes (due to button pressing), it was important to ensure that we had captured effects that were specific to cognitive processes in the DMN.…”

“…Although spontaneous increases of DMN activity are postulated to reflect mind-wandering, a highly consistent finding is that DMN activity is higher when ongoing behavior is stable rather than variable (19)(20)(21). This finding would be counterintuitive if there were a one-to-one mapping between mind-wandering intensity and DMN activity.…”

A Neural Model of Mind Wandering

“…Several recent studies found that activity in the DMN is inversely related to measures of behavioral variability (i.e., poorer task performance) [41][42][43]. For example, in a fingertapping task, increased tap variability was associated with reduced DMN activity [43] even though behavioral variability is consistently associated with mind wandering [44,45].…”