Stimulus-response Mapping Rules Research Articles

Linking the Brain with Behavior: The Neural Dynamics of Success and Failure in Goal-directed Behavior.

The human brain is extremely flexible and capable of rapidly selecting relevant information in accordance with task goals. Regions of frontoparietal cortex flexibly represent relevant task information such as task rules and stimulus features when participants perform tasks successfully, but less is known about how information processing breaks down when participants make mistakes. This is important for understanding whether and when information coding recorded with neuroimaging is directly meaningful for behavior. Here, we used magnetoencephalography to assess the temporal dynamics of information processing and linked neural responses with goal-directed behavior by analyzing how they changed on behavioral error. Participants performed a difficult stimulus-response task using two stimulus-response mapping rules. We used time-resolved multivariate pattern analysis to characterize the progression of information coding from perceptual information about the stimulus, cue and rule coding, and finally, motor response. Response-aligned analyses revealed a ramping up of perceptual information before a correct response, suggestive of internal evidence accumulation. Strikingly, when participants made a stimulus-related error, and not when they made other types of errors, patterns of activity initially reflected the stimulus presented, but later reversed, and accumulated toward a representation of the "incorrect" stimulus. This suggests that the patterns recorded at later time points reflect an internally generated stimulus representation that was used to make the (incorrect) decision. These results illustrate the orderly and overlapping temporal dynamics of information coding in perceptual decision-making and show a clear link between neural patterns in the late stages of processing and behavior.

Modifying food items valuation and weight with gamified executive control training.

Recent lines of research suggest that repeated executive control of motor responses to food items modifies their perceived value and in turn their consumption. Cognitive interventions involving the practice of motor control and attentional tasks have thus been advanced as potential approach to improve eating habits. Yet, their efficacy remains debated, notably due to a lack of proper control for the effects of expectations. We examined whether a one-month intervention combining the practice of Go/NoGo and Cue approach training modified the perceived palatability of food items (i.e. decrease in unhealthy and increase in healthy food items' palatability ratings), and in turn participants’ weights. We assessed our hypotheses with a parallel, double-blind, randomized controlled trial. Motivation and adherence to the intervention were maximized by a professional-level gamification of the training tasks. The control intervention differed from the experimental intervention only in the biasing of the stimulus–response mapping rules, enabling to balance expectations between the two groups and thus to conclude on the causal influence of motoric control on items valuation. We found a larger decrease of the unhealthy items' palatability ratings in the experimental (20.6%) than control group (13.1%). However, we did not find any increase of the healthy items’ ratings or weight loss. Overall, the present registered report confirms that the repeated inhibition of motor responses to food cues, together with the development of attentional biases away from these cues, reduces their perceived value.

Power of instructions for task implementation: superiority of explicitly instructed over inferred rules.

"Power of instructions" originally referred to automatic response activation associated with instructed rules, but previous examination of the power of instructed rules in actual task implementation has been limited. Typical tasks involve both explicit aspects (e.g., instructed stimulus-response mapping rules) and implied, yet easily inferred aspects (e.g., be ready, attend to error beeps) and it is unknown if inferred aspects also become readily executable like their explicitly instructed counterparts. In each mini-block of our paradigm we introduced a novel two-choice task. In the instructions phase, one stimulus was explicitly mapped to a response; whereas the other stimulus' response mapping had to be inferred. Results show that, in most cases, explicitly instructed rules were implemented more efficiently than inferred rules, but this advantage was observed only in the first trial following instructions (though not in the first implementation of the rules), which suggests that the entire task set was implemented in the first trial. Theoretical implications are discussed.

Spatiotemporal brain dynamics supporting the immediate automatization of inhibitory control by implementation intentions

While cognitive interventions aiming at reinforcing intentional executive control of unwanted response showed only modest effects on impulse control disorders, the establishment of fast automatic, stimulus-driven inhibition of responses to specific events with implementation intention self-regulation strategies has proven to be an effective remediation approach. However, the neurocognitive mechanisms underlying implementation intentions remain largely unresolved. We addressed this question by comparing electrical neuroimaging analyses of event-related potentials recorded during a Go/NoGo task between groups of healthy participants receiving either standard or implementation intentions instructions on the inhibition stimuli. Inhibition performance improvements with implementation intentions were associated with a Group by Stimulus interaction 200–250 ms post-stimulus onset driven by a selective decrease in response to the inhibition stimuli within the left superior temporal gyrus, the right precuneus and the right temporo-parietal junction. We further observed that the implementation intentions group showed already at the beginning of the task the pattern of task-related functional activity reached after practice in the group having received standard instructions. We interpret our results in terms of an immediate establishment of an automatic, bottom-up form of inhibitory control by implementation intentions, supported by stimulus-driven retrieval of verbally encoded stimulus-response mapping rules, which in turn triggered inhibitory processes.

Enhancing frontal top-down inhibitory control with Go/NoGo training.

Whether and how the capacity to inhibit cognitive and motor processes can be trained and the underlying neuroplastic mechanisms remain unclear. Using electrical neuroimaging methods, we investigated how inhibitory control training regimens can be designed to enhance frontal top-down inhibition processes. We trained participants with a Go/NoGo task in which the stimulus-response mapping rules were systematically varied. This task parameter has indeed be hypothesized to determine the extent to which top-down frontal inhibition processes are involved and thus ultimately reinforced during the training. The effects of training on inhibitory control were assessed by analyzing the event-related potentials (ERPs) measured during the Go/NoGo task with a data-driven time- and electrode-wise 2×2 ANOVA with factors Session (beginning; end of the training) and Stimuli (Go; NoGo). To localize the sources of the ERP effects in the brain, the same statistical design was applied to distributed electrical source estimations averaged over the periods of ERP modulations. The training improved inhibitory control performance. Electrophysiologically, we found a significant Session×Stimulus interaction at 300-400ms post-stimulus onset over centro-occipital electrodes. Statistical parametric mapping on the brain source estimations revealed an interaction within right inferior frontal cortices driven by a decrease in response strength to NoGo but not to Go trials in this region. Our collective results demonstrate that frontal top-down inhibition processes can be enhanced with specifically designed inhibitory control training regimens.

Parietal cortex contributions to information granules following memory consolidation

Previous studies have focused on changes in cerebral cortex activity accompanying memory formation and consolidation. Although the role of the parietal cortex in memory retrieval is well established, it is not well understood how parietal cortex memory consolidation for mathematical rules is related to granularity of stored information (i.e., degree of detail or precision). Changes in parietal cortex activity associated with memory consolidation were analyzed using the Ebbinghaus paradigm and functional magnetic resonance imaging (fMRI). Over the course of 1 week, participants learned Boolean arithmetic tasks involving stimulus-response mapping rules containing either low- or high-granularity information. FMRI images were collected on day 1 (i.e., low-granularity condition) and day 7 (i.e., high-granularity condition). The present data suggested that with practice, stored information was converted from a low-granularity to a high-granularity form. By following rule learning, it was hypothesized that the process of consolidation would involve an increased degree of rule representation granularity. Evidence for this process was reflected in parietal cortex activity. This finding was consistent with the hypothesis that mnemonic reconstruction in the parietal cortex is required for memory consolidation, and results suggested that information granules are formed during memory consolidation. The present results could increase the understanding of the relationship between memory consolidation and information granularity.

Decoding cognitive control in human parietal cortex.

Efficient execution of perceptual-motor tasks requires rapid voluntary reconfiguration of cognitive task sets as circumstances unfold. Such acts of cognitive control, which are thought to rely on a network of cortical regions in prefrontal and posterior parietal cortex, include voluntary shifts of attention among perceptual inputs or among memory representations, or switches between categorization or stimulus-response mapping rules. A critical unanswered question is whether task set shifts in these different domains are controlled by a common, domain-independent mechanism or by separate, domain-specific mechanisms. Recent studies have implicated a common region of medial superior parietal lobule (mSPL) as a domain-independent source of cognitive control during shifts between perceptual, mnemonic, and rule representations. Here, we use fMRI and event-related multivoxel pattern classification to show that spatial patterns of brain activity within mSPL reliably express which of several domains of cognitive control is at play on a moment-by-moment basis. Critically, these spatiotemporal brain patterns are stable over time within subjects tested several months apart and across a variety of tasks, including shifting visuospatial attention, switching categorization rules, and shifting attention in working memory.

A Domain-Independent Source of Cognitive Control for Task Sets: Shifting Spatial Attention and Switching Categorization Rules

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.

Selective activation of the superior frontal gyrus in task-switching: An event-related fNIRS study

In the task-switching paradigm, reaction time is longer and accuracy is worse in switch trials relative to repetition trials. This so-called switch cost has been ascribed to the engagement of control processes required to alternate between distinct stimulus–response mapping rules. Neuroimaging studies have reported an enhanced activation of the human lateral prefrontal cortex and the superior frontal gyrus during the task-switching paradigm. Whether neural activation in these regions is dissociable and associated with separable cognitive components of task switching has been a matter of recent debate. We used multi-channel near-infrared spectroscopy (fNIRS) to measure brain cortical activity in a task-switching paradigm designed to avoid task differences, order predictability, and frequency effects. The results showed a generalized bilateral activation of the lateral prefrontal cortex and the superior frontal gyrus in both switch trials and repetition trials. To isolate the activity selectively associated with the task-switch, the overall activity recorded during repetition trials was subtracted from the activity recorded during switch trials. Following subtraction, the remaining activity was entirely confined to the left portion of the superior frontal gyrus. The present results suggest that factors associated with load and maintenance of distinct stimulus–response mapping rules in working memory are likely contributors to the activation of the lateral prefrontal cortex, whereas only activity in the left superior frontal gyrus can be linked unequivocally to switching between distinct cognitive tasks.

Anticipation of conflict monitoring in the anterior cingulate cortex and the prefrontal cortex.

The anterior cingulate cortex (ACC) has been suggested as a monitoring center that is responsible for online detection of response conflicts. In this view, the conflict signal detected by the ACC is transmitted to other brain regions, such as the dorsal part of the lateral prefrontal cortex (lPFC), to increase the level of cognitive control. In this functional MRI (fMRI) study, we examined the conflict resolution that goes beyond online detection of response conflicts. Participants learned pseudoarithmetic problem-solving tasks that involve stimulus-response mapping rules with high or low conflicts. On half of the trials, participants had a preview of the upcoming operator that allowed advance preparation for the mapping rules. The preview significantly reduced the conflict effects on latency. During the preview, both the ACC and lPFC were activated in anticipation of conflict, and this anticipatory activation was highly predictive of the subsequent latency. These results suggest that the ACC and lPFC are responsible for both anticipatory preparation and online adjustment in response to conflicts. The results also confirm the roles of the lPFC and ACC in managing conflict during problem solving and extend these roles to include responding to anticipation of conflicts that may arise between incompatible stimulus-response mappings maintained in working memory during preparation.

Task- and location-switching effects on visual attention

In two experiments, we examined the effects of task and location switching on the accuracy of reporting target characters in an attentional blink (AB) paradigm. Single-character streams were presented at a rate of 100 msec per character in Experiment 1, and successive pairs of characters on either side of fixation were presented in Experiment 2. On each trial, two targets appeared that were either white letters or black digits embedded in a stream of black letter distractors, and they were separated by between zero and five items in the stream (lags 1-6). Experiment 1 showed that report of the first target was least accurate if it immediately preceded the second target and if the two targets were either both letters or both digits (task repetition cost). Report of the second target was least accurate if one or two distractors intervened between the two targets (the U-shaped AB lag effect) and if one target was a letter and the other a digit (task switch cost). Experiment 2 added location uncertainty as a factor and showed similar effects as Experiment 1, with one exception. Lag 1 sparing (the preserved accuracy in reporting the second of two targets if the second immediately follows the first) was completely eliminated when the task required attention switching across locations. Two-way additive effects were found between task switching and location switching in the AB paradigm. These results suggests separate loci for their attentional effects. It is likely that the AB deficit is due mainly to central memory limitations, whereas location-switching costs occur at early visual levels. Task-switching costs occur at an intermediate visual level, since the present task switch involved encoding differences without changes in stimulus-response mapping rules (i.e., the task was character identification for both letters and digits).

Stimulus–response translation in manual and vocal modality: Is age‐related slowing influenced by changes in working memory functioning?

In some conditions, age‐related slowing rates are higher for manual than for vocal responses. The interaction between age and response modality was examined in four experiments in which the performance of younger (M = 22.6 years) and older (M = 70.8 years) adults was compared under various stimulus–response mapping rules. The interaction effect was not observed in a simple localisation task on which the manual modality had an advantage in both age groups (Experiment 1). When congruence between stimulus and response was reduced (Experiment 2), manual responses were disproportionately slowed in older participants. In conceptual and size comparison tasks (Experiment 3), the age‐by‐modality effect was not influenced by working memory load during the interval between the first and the second stimulus presentation. In an identification task, age‐related slowing effects were less when responses were spoken names than when nonwords were used as labels (Experiment 4). These results indicate that older participants experience a specific difficulty in activating arbitrary S–R mapping rules during executive control.

Attention Systems and the Organization of the Human Parietal Cortex

Event-related functional magnetic resonance imaging was used to compare activity in the human parietal cortex in two attention-switching paradigms. On each trial of the visual switching (VS) paradigm, subjects attended to one of two visual stimuli on the basis of either their color or shape. Trials were presented in blocks interleaved with cues instructing subjects to either continue attending to the currently relevant dimension or to switch to the other stimulus dimension. In the response switching (RS) paradigm, subjects made one of two manual responses to the single stimulus presented on each trial. The rules for stimulus-response mapping were reversed on different trials. Trials were presented in blocks interleaved with cues that instructed subjects to either switch stimulus-response mapping rules or to continue with the current rule. Brain activity at "switch" and "stay" events was compared. The results revealed distinct parietal areas concerned with visual attentional set shifts (VS) and visuomotor intentional set shifts (RS). In VS, activity was recorded in the lateral part of the intraparietal region. In RS, activity was recorded in the posterior medial intraparietal region and adjacent posterior superior and dorsomedial parietal cortex. The results also suggest that the basic functional organization of the intraparietal sulcus and surrounding regions is similar in both macaque and human species.

Attention systems and the organization of the human parietal cortex

Event-related functional magnetic resonance imaging was used to compare activity in the human parietal cortex in two attention-switching paradigms. On each trial of the visual switching (VS) paradigm, subjects attended to one of two visual stimuli on the basis of either their color or shape. Trials were presented in blocks interleaved with cues instructing subjects to either continue attending to the currently relevant dimension or to to the other stimulus dimension. In the response switching (RS) paradigm, subjects made one of two manual responses to the single stimulus presented on each trial. The rules for stimulus-response mapping were reversed on different trials. Trials were presented in blocks interleaved with cues that instructed subjects to either stimulus-response mapping rules or to continue with the current rule. Brain activity at switch and stay events was compared. The results revealed distinct parietal areas concerned with visual attentional set shifts (VS) and visuomotor intentional set shifts (RS). In VS, activity was recorded in the lateral part of the intraparietal region. In RS, activity was recorded in the posterior medial intraparietal region and adjacent posterior superior and dorsomedial parietal cortex. The results also suggest that the basic functional organization of the intraparietal sulcus and surrounding regions is similar in both macaque and human species.

The Basis of Stroop Interference Involving the Multimodal Correlates of Auditory Pitch

A pure auditory tone has a range of multimodal qualities that are determined by its pitch. A reaction-time task was used to demonstrate that subjects respond immediately and automatically to these qualities. Subjects were required to press one of two keys depending on which word, from a limited set, appeared on a microcomputer screen. The words were antonyms that represented multimodal stimulus qualities, and they were assigned to alternative responses so that the two words that shared the same response were correlated in the same way with pitch. As an incidental stimulus, either a 50 Hz tone or a 5500 Hz tone accompanied the presentation of each word. Subjects were found to respond more slowly when the multimodal qualities of the tone were incongruent with the qualities represented by the test word. When the stimulus-response mapping rules were changed, however, the Stroop effect did not occur; suggesting that a polarised semantic code of the incidental tone, that embraces its multimodal features, accesses the same semantic register as the equivalent code for the test word itself.