Behavioral and neurophysiological evidence for increased cognitive flexibility in late childhood

Electrophysiological correlates of the effect of set size on object switching in working memory

Previous studies have revealed the effect of set size (the number of activated items) on object switching in working memory, but the underlying neural mechanism remains unclear. In this study, participants were asked to first remember two (small size) or three (large size) two-digit numbers and the corresponding geometrical figures as different references for numerical comparison and then compare a series of numbers (10-99) to the reference numbers cued by different geometrical figures. The cue repeated or switched across trials. Behavioral results revealed that the switch cost was greater in the large-size condition than in the small-size condition. Event-related potential results showed that in the N2 component, an interaction was observed between set size and transition, with a significant transition effect (switch minus repeat) in the large-size condition and a non-significant transition effect in the small-size condition. The same interaction was observed in the P3 component, with a larger amplitude difference (switch minus repeat) in the large-size condition than in the small-size condition. These results suggested that when set size is increased, the effort to inhibit the irrelevant items increases, resulting in large cost of object switching in working memory.

Protocol to decode representations from EEG data with intermixed signals using temporal signal decomposition and multivariate pattern-analysis

The electroencephalogram (EEG) is one of the most widely used techniques in cognitive neuroscience. We present a protocol showing how to combine a temporal signal decomposition approach (RIDE, Residue iteration decomposition) with multivariate pattern analysis (MVPA) to obtain insights into the temporal stability of representations coded in distinct informational fractions of the EEG signal. In this protocol, we describe pre-processing of human EEG data, followed by the set-up and use of MATLAB-based toolboxes for RIDE and MVPA analysis.

For complete details on the use and execution of this protocol, please refer to Petruo et al. (2021).

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A protocol for decoding temporally decomposed EEG signal

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Steps for Residue iteration decomposition (RIDE) and handling the decomposed data

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Steps for subsequent multivariate pattern analysis (MVPA) with different toolboxes

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Recommendations for combined RIDE-MVPA research applications

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Multi-level decoding of task sets in neurophysiological data during cognitive flexibility

Cognitive flexibility is essential to achieve higher level goals. Cognitive theories assume that the activation/deactivation of goals and task rules is central to understand cognitive flexibility. However, how this activation/deactivation dynamic is implemented on a neurophysiological level is unclear. Using EEG-based multivariate pattern analysis (MVPA) methods, we show that activation of relevant information occurs parallel in time at multiple levels in the neurophysiological signal containing aspects of stimulus-related processing, response selection, and motor response execution, and relates to different brain regions. The intensity with which task sets are activated and processed dynamically decreases and increases. The temporal stability of these activations could, however, hardly explain behavioral performance. Instead, task set deactivation processes associated with left orbitofrontal regions and inferior parietal regions selectively acting on motor response task sets are relevant. The study shows how propositions from cognitive theories stressing the importance task set activation/deactivation during cognitive flexibility are implemented on a neurophysiological level.

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Stimulus-related, motor, and response selection aspects of task set were decoded

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Activation of task rule information occurs at multiple neurophysiological levels

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Activation and deactivation of rule sets contributes to cognitive flexibility

Clustering and switching in divergent thinking: Neurophysiological correlates underlying flexibility during idea generation

EEG alpha synchronization, especially in posterior parietal cortical regions of the right hemisphere, is indicative of high internal processing demands that are typically involved in divergent thinking (DT). During the course of DT, as ideation proceeds, ideas tend to become more creative, being more likely to be drawn from new conceptual categories through the use of the cognitive mechanism of flexibility. The present study investigated whether EEG alpha synchronization can be modulated by flexibility in DT by comparing cortical activation patterns during the switch of category (switching) and the stay in the same category (clustering). Twenty participants were required to generate alternative uses of everyday objects during EEG recording. Differential results were specifically found in the lower alpha band (8-10 Hz): whereas clustering showed synchronization typically lateralized in the right posterior parietal areas, switching induced posterior parietal synchronization over both right and left hemispheres. These findings indicate that the two distinct cognitive mechanisms subsuming flexibility (switching and clustering) are associated with a different hemispheric modulation of lower alpha activity, as switching, in comparison to clustering, is related to higher power in the lower alpha band over the left hemisphere. Switching in comparison to clustering may thus require a larger investment of cognitive resources due to the exploratory process of moving from one semantic conceptual category to another in the course of creative ideation.

Short-term Smartphone App–Based Focused Attention Meditation Diminishes Cognitive Flexibility

Cognitive flexibility is an important aspect relevant to daily life situations, and there is an increasing public interest to optimize these functions, for example, using (brief) meditation practices. However, the underlying neurophysiological mechanisms remain poorly understood. On the basis of theoretical considerations, both improvements and deteriorations of cognitive flexibility are possible through focused attention meditation (FAM). We investigated the effect of a brief smartphone app–based FAM on task switching using EEG methods, temporal signal decomposition, and source localization techniques (standardized low-resolution electromagnetic brain tomography). The study was conducted using a crossover study design. We show that even 15 min of FAM practicing modulates memory-based task switching, on a behavioral level and a neurophysiological level. More specifically, FAM hampers response selection and conflict resolution processes and seem to reduce cognitive resources, which are necessary to rapidly adapt to changing conditions. These effects are represented in the N2 and P3 time windows and associated with ACC. It seems that FAM increases the attention to one specific aspect, which may help to focus but carries also the risk that behavior becomes too rigid. FAM thus seems to modulate both the stimulus- and response-related aspects of conflict monitoring in ACC. Motor-related processes were not affected. The results can be explained using a cognitive control dilemma framework, suggesting that particularly alterations in background monitoring may be important to consider when explaining the effects of FAM during task switching.

EEG Signal Decomposition Evidence for a Role of Perceptual Processes during Conflict-related Behavioral Adjustments in Middle Frontal Regions

Conflict monitoring processes are central to cope with fluctuating environmental demands. However, the efficacy of these processes depends on previous trial history/experience, which is reflected in the "congruency sequence effect" (CSE). Several theoretical accounts have been put forward to explain this effect. Some accounts stress the role of perceptual processes in the emergence of the CSE. As yet, it is elusive how these perceptual processes are implemented on a neural level. We examined this question using a newly developed moving dots flanker task. We combine decomposition methods of EEG data and source localization. We show that perceptual processes modulate the CSE and can be isolated in neurophysiological signals, especially in the N2 ERP time window. However, mechanisms relating perception to action are also coded and modulated in this time window. We show that middle frontal regions (BA 6) are associated with processes dealing with purely perceptual processes. Inferior frontal regions (BA 45) are associated with processes dealing with stimulus-response transition processes. Likely, the neurophysiological modulations reflect unbinding processes at the perceptual level, and stimulus-response translation level needed to respond correctly on the presented (changed) stimulus-response relationships. The data establish a direct relationship between psychological concepts focusing on perceptual processes during conflict monitoring and neurophysiological processes using signal decomposition.

Working memory load affects repetitive behaviour but not cognitive flexibility in adolescent autism spectrum disorder

OBJECTIVES

Autism spectrum disorder (ASD) is associated with repetitive and stereotyped behaviour, suggesting that cognitive flexibility may be deficient in ASD. A central, yet not examined aspect to understand possible deficits in flexible behaviour in ASD relates (i) to the role of working memory and (ii) to neurophysiological mechanisms underlying behavioural modulations.

METHODS

We analysed behavioural and neurophysiological (EEG) correlates of cognitive flexibility using a task-switching paradigm with and without working memory load in adolescents with ASD and typically developing controls (TD).

RESULTS

Adolescents with ASD versus TD show similar performance in task switching with no memory load, indicating that 'pure' cognitive flexibility is not in deficit in adolescent ASD. However performance during task repetition decreases with increasing memory load. Neurophysiological data reflect the pattern of behavioural effects, showing modulations in P2 and P3 event-related potentials.

CONCLUSIONS

Working memory demands affect repetitive behaviour while processes of cognitive flexibility are unaffected. Effects emerge due to deficits in preparatory attentional processes and deficits in task rule activation, organisation and implementation of task sets when repetitive behaviour is concerned. It may be speculated that the habitual response mode in ASD (i.e. repetitive behaviour) is particularly vulnerable to additional demands on executive control processes.

Information processes of task-switching and modality-shifting across development

Developmental research on flexible attentional control in young children has often focused on the role of attention in task-switching in a unimodal context. In real life, children must master the art of switching attention not only between task demands, but also between sensory modalities. Previous study has shown that young children can be efficient at switching between unimodal tasks when the situation allows, incurring no greater task-switching costs than adults. However, young children may still experience a greater demand to shift attention between modalities than older participants. To address this, we tested 4-year-olds, 6-year-olds and adults on a novel cross-modal task-switching paradigm involving multisensory detection tasks. While we found age differences in absolute reaction time and accuracy, young children and adults both exhibited strikingly similar effects in task-switching, modality-shifting, and the interaction between them. Young children did not exhibit a greater attentional bottleneck on either the task level, or on the modality level; thus, the evidence suggests that young children engaged in similar cognitive operations in the current cross-modal tasks to adult participants. It appears that cognitive operations in multisensory task configuration are relatively mature between 4 and 6 years old.

On the role of the prefrontal cortex in fatigue effects on cognitive flexibility - a system neurophysiological approach

Demanding tasks like cognitive flexibility show time-related deterioration of performance (i.e. fatigability effects). Fatigability has been associated with structural and functional properties of the prefrontal cortex. However, the electrophysiological underpinnings of these processes are not well understood. We examined n = 34 healthy participants with a task switching paradigm in which switches were either signaled by cues or needed to be maintained by working memory processes. We analyzed event-related potentials (ERPs) and performed residue iteration decomposition (RIDE) to account for effects of fatigue on intra-individual variability of neurophysiological data. This was combined with source localization methods. We show that task switching is affected by time on task (TOT) effects mostly when working memory processes are needed. On a neurophysiological level, this effect could not be observed in standard ERPs, but only after accounting for intra-individual variability using RIDE. The RIDE data suggests that during task switching, fatigability specifically affects response recoding processes that are associated with functions of the middle frontal gyrus (MFG; BA10). The results underline propositions of the ‘opportunity cost model’, which states that fatigability effects of executive functions depend on the degree to which tasks engage similar prefrontal regions - in this case working memory and task switching mechanisms.

Different Electrophysiological Responses to Informative Value of Feedback Between Children and Adults

The ability to learn from feedback is important for children's adaptive behavior and school learning. Feedback has two main components, informative value and valence. How to disentangle these two components and what is the developmental neural correlates of using the informative value of feedback is still an open question. In this study, 23 children (7-10 years old) and 19 adults (19-22 years old) were asked to perform a rule induction task, in which they were required to find a rule, based on the informative value of feedback. Behavioral results indicated that the likelihood of correct searching behavior under negative feedback was low for children. Event-related potentials showed that (1) the effect of valence was processed in a wide time window, particularly in the N2 component; (2) the encoding process of the informative value of negative feedback began later for children than for adults; (3) a clear P300 was observed for adults; for children, however, P300 was absent in the frontal region; and (4) children processed the informative value of feedback chiefly in the left sites during the P300 time window, whereas adults did not show this laterality. These results suggested that children were less sensitive to the informative value of negative feedback possibly because of the immature brain.

Effects of high-dose ethanol intoxication and hangover on cognitive flexibility

The effects of high-dose ethanol intoxication on cognitive flexibility processes are not well understood, and processes related to hangover after intoxication have remained even more elusive. Similarly, it is unknown in how far the complexity of cognitive flexibility processes is affected by intoxication and hangover effects. We performed a neurophysiological study applying high density electroencephalography (EEG) recording to analyze event-related potentials (ERPs) and perform source localization in a task switching paradigm which varied the complexity of task switching by means of memory demands. The results show that high-dose ethanol intoxication only affects task switching (i.e. cognitive flexibility processes) when memory processes are required to control task switching mechanisms, suggesting that even high doses of ethanol compromise cognitive processes when they are highly demanding. The EEG and source localization data show that these effects unfold by modulating response selection processes in the anterior cingulate cortex. Perceptual and attentional selection processes as well as working memory processes were only unspecifically modulated. In all subprocesses examined, there were no differences between the sober and hangover states, thus suggesting a fast recovery of cognitive flexibility after high-dose ethanol intoxication. We assume that the gamma-aminobutyric acid (GABAergic) system accounts for the observed effects, while they can hardly be explained by the dopaminergic system.

On the relevance of the alpha frequency oscillation's small-world network architecture for cognitive flexibility

Cognitive flexibility is a major requirement for successful behavior. nNeural oscillations in the alpha frequency band were repeatedly associated with cognitive flexibility in task-switching paradigms. Alpha frequencies are modulated by working memory load and are used to process information during task switching, however we do not know how this oscillatory network communication is modulated. In order to understand the mechanisms that drive cognitive flexibility, ERPs, oscillatory power and how the communication within these networks is organized are of importance. The EEG data show that during phases reflecting preparatory processes to pre-activate task sets, alpha oscillatory power but not the small world properties of the alpha network architecture was modulated. During the switching only the N2 ERP component showed clear modulations. After the response, alpha oscillatory power reinstates and therefore seems to be important to deactivate or maintain the previous task set. For these reactive control processes the network architecture in terms of small-world properties is modulated. Effects of memory load on small-world aspects were seen in repetition trials, where small-world properties were higher when memory processes were relevant. These results suggest that the alpha oscillatory network becomes more small-world-like when reactive control processes during task switching are less complex.

Specific neurophysiological mechanisms underlie cognitive inflexibility in inflammatory bowel disease

Inflammatory bowel disease (IBD) is highly prevalent. While the pathophysiological mechanisms of IBD are increasingly understood, there is a lack of knowledge concerning cognitive dysfunctions in IBD. This is all the more the case concerning the underlying neurophysiological mechanisms. In the current study we focus on possible dysfunctions of cognitive flexibility (task switching) processes in IBD patients using a system neurophysiological approach combining event-related potential (ERP) recordings with source localization analyses. We show that there are task switching deficits (i.e. increased switch costs) in IBD patients. The neurophysiological data show that even though the pathophysiology of IBD is diverse and wide-spread, only specific cognitive subprocesses are altered: There was a selective dysfunction at the response selection level (N2 ERP) associated with functional alterations in the anterior cingulate cortex and the right inferior frontal gyrus. Attentional selection processes (N1 ERP), perceptual categorization processes (P1 ERP), or mechanisms related to the flexible implementation of task sets and related working memory processes (P3 ERP) do not contribute to cognitive inflexibility in IBD patients and were unchanged. It seems that pathophysiological processes in IBD strongly compromise cognitive-neurophysiological subprocesses related to fronto-striatal networks. These circuits may become overstrained in IBD when cognitive flexibility is required.

Task intentions and their implementation into actions: cognitive control from adolescence to middle adulthood

Cognitive control processes involved in human multitasking arise, mature, and decline across age. This study investigated how age modulates cognitive control at two different levels: the level of task intentions and the level of the implementation of intentions into the corresponding actions. We were particularly interested in specifying maturation of voluntary task choice (intentions) and task-switching execution (their implementations) between adolescence and middle adulthood. Seventy-four participants were assigned to one of the four age groups (adolescents, 12-17 years; emerging adults, 18-22 years; young adults, 23-27 years; middle-aged adults, 28-56 years). Participants chose between two simple cognitive tasks at the beginning of each trial before pressing a spacebar to indicate that the task choice was made. Next, a stimulus was presented in one of the three adjacent boxes, with participants identifying either the location or the shape of the stimulus, depending on their task choice. This voluntary task-switching paradigm allowed us to investigate the intentional component (task choice) separately from its implementation (task execution). Although all participants showed a tendency to repeat tasks more often than switching between them, this repetition bias was significantly stronger in adolescents than in any adult group. Furthermore, participants generally responded slower after task switches than after task repetitions. This switch cost was similar across tasks in the two younger groups but larger for the shape than the location task in the two older groups. Together, our results demonstrate that both task intentions and their implementation into actions differ across age in quite specific ways.

Self-Regulatory Capacities Are Depleted in a Domain-Specific Manner

Performing an act of self-regulation such as making decisions has been suggested to deplete a common limited resource, which impairs all subsequent self-regulatory actions (ego depletion theory). It has however remained unclear whether self-referred decisions truly impair behavioral control even in seemingly unrelated cognitive domains, and which neurophysiological mechanisms are affected by these potential depletion effects. In the current study, we therefore used an inter-individual design to compare two kinds of depletion, namely a self-referred choice-based depletion and a categorization-based switching depletion, to a non-depleted control group. We used a backward inhibition (BI) paradigm to assess the effects of depletion on task switching and associated inhibition processes. It was combined with EEG and source localization techniques to assess both behavioral and neurophysiological depletion effects. The results challenge the ego depletion theory in its current form: Opposing the theory’s prediction of a general limited resource, which should have yielded comparable effects in both depletion groups, or maybe even a larger depletion in the self-referred choice group, there were stronger performance impairments following a task domain-specific depletion (i.e., the switching-based depletion) than following a depletion based on self-referred choices. This suggests at least partly separate and independent resources for various cognitive control processes rather than just one joint resource for all self-regulation activities. The implications are crucial to consider for people making frequent far-reaching decisions e.g., in law or economy.

Modulations of cognitive flexibility in obsessive compulsive disorder reflect dysfunctions of perceptual categorization

BACKGROUND

Despite cognitive inflexibility is trait like in obsessive compulsive disorder (OCD) patients and underlies clinical symptomatology, it is elusive at what stage of information processing deficits, leading to cognitive inflexibility, emerges. We hypothesize that inhibitory control mechanisms during early stimulus categorization and integration into a knowledge system underlie these deficits.

METHODS

We examined N = 25 adolescent OCD patients and matched healthy controls (HC) in a paradigm manipulating the importance of the knowledge system to perform task switching. This was done using a paradigm in which task switches were signaled either by visual stimuli or by working memory processes. This was combined with event-related potential recordings and source localization.

RESULTS

Obsessive compulsive disorder patients showed increased switch costs in the memory as compared with the cue-based block, while HC showed similar switch costs in both blocks. At the neurophysiological level, these changes in OCD were not reflected by the N2 and P3 reflecting response-associated processes but by the P1 reflecting inhibitory control during sensory categorization processes. Activation differences in the right inferior frontal gyrus and superior temporal gyrus are associated with the P1 effect.

CONCLUSIONS

Cognitive flexibility in adolescent OCD patients is strongly modulated by working memory load. Contrary to common sense, not response-associated processes, but inhibitory control mechanisms during early stimulus categorization processes are likely to underlie cognitive inflexibility in OCD. These processes are associated with right inferior frontal and superior temporal gyrus mechanisms.

Dysfunctions in striatal microstructure can enhance perceptual decision making through deficits in predictive coding

An important brain function is to predict upcoming events on the basis of extracted regularities of previous inputs. These predictive coding processes can disturb performance in concurrent perceptual decision-making and are known to depend on fronto-striatal circuits. However, it is unknown whether, and if so, to what extent striatal microstructural properties modulate these processes. We addressed this question in a human disease model of striosomal dysfunction, i.e. X-linked dystonia-parkinsonism (XDP), using high-density EEG recordings and source localization. The results show faster and more accurate perceptual decision-making performance during distraction in XDP patients compared to healthy controls. The electrophysiological data show that sensory memory and predictive coding processes reflected by the mismatch negativity related to lateral prefrontal brain regions were weakened in XDP patients and thus induced less cognitive conflict than in controls as reflected by the N2 event-related potential (ERP). Consequently, attentional shifting (P3a ERP) and reorientation processes (RON ERP) were less pronounced in the XDP group. Taken together, these results suggests that striosomal dysfunction is related to predictive coding deficits leading to a better performance in concomitant perceptual decision-making, probably because predictive coding does not interfere with perceptual decision-making processes. These effects may reflect striatal imbalances between the striosomes and the matrix compartment.