A domain-independent source of cognitive control for task sets: shifting spatial attention and switching categorization rules

Abstract

To optimize task performance as circumstances unfold, cognitive control mechanisms configure the brain to prepare for upcoming events through voluntary shifts in task set. A foundational unanswered question concerns whether different domains of cognitive control (e.g., spatial attention shifts, shifts between categorization rules, or shifts between stimulus-response mapping rules) are associated with separate, domain-specific control mechanisms, or whether a common, domain-independent source of control initiates shifts in all domains. Previous studies have tested different domains of cognitive control in separate groups of subjects using different paradigms, yielding equivocal conclusions. Here, using rapid event-related MRI, we report evidence from a single paradigm in which subjects were cued to perform both shifts of spatial attention and switches between categorization rules. A conjunction analysis revealed a common transient signal evoked by switch cues in medial superior parietal lobule for both domains of control, revealing a single domain-independent control mechanism.

Figure 1.

a, Behavioral task. In this example, subjects are instructed at the start of the run to attend to the left central RSVP stream and to prepare to perform the magnitude categorization. When a digit (e.g., “4”) is presented, they perform the high/low judgment on this digit. When the “R” cue is presented in the attended stream, they shift attention covertly to the right central RSVP stream and continue to prepare the magnitude categorization. When the “P” cue is presented in the attended stream, they switch to the parity categorization rule and wait for a digit to perform the odd/even judgment. Each RSVP frame lasts for 250 ms with no temporal gap between frames. Each critical event (cue or target) is separated by 3000–9000 ms. b, Four possible preparatory states subjects could occupy during the task; the double-headed arrows indicate the eight possible switches. c, Behavioral performance: response times and accuracy to targets (mean ± 1 SEM).

Figure 2.

Sustained effects of spatial attention (attend left vs attend right) in extrastriate cortex. The event-related average time courses were computed as percentage signal change relative to the mean BOLD signal across the entire run. Time 0 is when the cue event in question occurred. hL and hR cues produced sustained contralateral activity in each area that did not change when the hold cue appeared; sLR and sRL transitioned from relatively low to sustained high levels of activity (or vice versa) after shift cues. Error bands show ±1 SEM.

Figure 3.

Sources of cognitive control for shifting spatial attention (attSh > attHd). The event-related average time courses are shown for each instance of attention shifts and holds.

Figure 4.

Sources of cognitive control for switching between two categorization rules (rulSw > rulHd). The event-related average time courses are shown for each instance of rule switches and holds.

Figure 5.

Common sources of control for shifting spatial attention and switching categorization rule. The conjunction analysis revealed the overlapping activation in mSPL for attSh > attHd and rulSw > rulHd.

Figure 6.

Event-related time course in mSPL evoked by the second switch cue in a pair as a function of whether the switches were in the same or different domains. The first switch cue occurred <12 s before the onset of the second switch cue.

Figure 7.

Event-related time course evoked by rule switch cues for trials in which the subsequent target response time fell within the fastest or slowest RT quartiles and the average of two middle quartiles. a, mSPL; b, left IPS.

Figure 8.

Execution-dependent cognitive control for rule switching. Mean event-related time course evoked by targets that followed a rule-switch cue (T_rulSw), a rule-hold cue (mean of T_rulHd), or a same-rule target (T_T) in pre-SMA.