Electrophysiological correlates of anticipatory and poststimulus components of task switching

Age-related Electrophysical Correlates of Cross-modal Attention Switching

The human experience demands seamless attentional switches between sensory modalities. Aging raises questions about how declines in auditory and visual processing affect cross-modal attention switching. This study used a cued cross-modal attention-switching paradigm where visual and auditory stimuli were simultaneously presented on either spatially congruent or incongruent sides. A modality cue indicated the target modality, requiring a spatially left versus right key-press response. EEG recordings were collected during task performance. We investigated whether the mixing costs (decreased performance for repetition trials in a mixed task compared with a single task) and switch costs (decreased performance for a switch of target modality compared with a repetition) in cross-modal attention-switching paradigms would exhibit similarities in terms of behavioral performance and the ERP components to those observed in the traditional unimodal attention-switching paradigms. Specifically, we focused on the ERP components: cue-locked P3 (mixing/switch-related increased positivity), target-locked P3 (mixing/switch-related decreased positivity), and target-locked lateralized readiness potential (mixing/switch-related longer latency). In addition, we assessed how aging impacts cross-modal attention-switching performance. Results revealed that older adults exhibited more pronounced mixing and switch costs than younger adults, especially when visual and auditory stimuli were presented on incongruent sides. ERP findings showed increased cue-locked P3 amplitude, prolonged cue-locked P3 latency, decreased target-locked P3 amplitude, prolonged target-locked P3 latency in association with switch costs, and prolonged onset latency of the target-locked lateralized readiness potential in association with the mixing costs. Age-related effects were significant only for cue-locked P3 amplitude, cue-locked P3 latency (switch-related), and target-locked P3 latency (switch-related). These findings suggest that the larger mixing costs and switch costs in older adults were due to the inefficient use of modality cues to update a representation of the relevant task sets, requiring more processing time for evaluating and categorizing the target.

Impaired cognitive flexibility in major depressive disorder: Evidences from spatial-temporal ERPs analysis

BACKGROUND

Major Depressive Disorder (MDD) may exhibit impairments in cognitive flexibility. This study investigated whether the cognitive flexibility deficits in MDD are evident across general stimuli or specific to emotional stimuli, while exploring the underlying neuropsychological mechanism.

METHODS

A total of 41 MDD patients and 42 healthy controls (HCs) were recruited. Event-related potentials (ERPs) were recorded when participants performed a non-emotional and an emotional task switching paradigm (N-ETSP and ETSP), both of which assessed cognitive flexibility. Microstate and source localization analysis were applied to reflect brain activity among different brain areas during task switching.

RESULTS

In the N-ETSP, MDD group showed larger P3 difference wave (Pd3) amplitudes and longer P2 difference wave (Pd2) latencies. In the ETSP, MDD group displayed smaller N2 difference wave (Nd2) amplitudes and larger Pd3 amplitudes. The comparison of sLORETA images of emotional switch task and emotional repeat task showed that MDD group had increased activation in the precentral gyrus in microstate2 of the P2 time window and had reduced activation in the middle occipital gyrus in microstate3 of the N2 time window.

LIMITATIONS

The cross-sectional design failed to capture dynamic changes in cognitive flexibility in MDD.

CONCLUSIONS

MDD demonstrated impaired cognitive flexibility respond to both non-emotional and emotional stimuli, with greater impairment for negative emotional stimuli. These deficits are evident in abnormal ERPs component during the early attention stage and the later task preparation stage. Furthermore, abnormal emotional switching cost in MDD appears to be related to early abnormal perceptual control in the parietal-occipital cortex.

High autistic traits linked with reduced performance on affective task switching: An ERP study

Few studies have investigated affective flexibility in individuals with high autistic traits. In the present study, we employed affective task-switching paradigm combined with event related potential (ERP) technology to explore affective flexibility in individuals with high autistic traits. Participants were instructed to switch between identifying the gender (gender task) and emotion (emotion task) of presented faces. Two groups of participants were recruited based on the Autism Spectrum Quotient (AQ) scores: a High Autistic Group (HAG) and a Low Autistic Group (LAG). The results confirmed that the HAG exhibited greater behavioral emotion switch costs and increased N2 and decreased P3 components when switching to the emotion task. Additionally, we identified an affective asymmetric switch cost in the HAG, where the switch cost for the emotion task was larger than for the gender task at both behavioral and electrophysiological levels. In contrast, a symmetrical switch cost was observed in the LAG. These findings indicate that the HAG experiences difficulties with affective flexibility, particularly in tasks involving emotional processing. The patterns of affective asymmetric switch costs observed in both groups differed from previous results in autistic children and the general population, suggesting that the relative dominance of gender and emotion tasks may vary between the two groups. We propose that the dominance of emotion tasks declines as autistic traits increase.

Exploring "phasic" vs. "tonic" accounts of the effect of switch probability on the auditory attention switch cost

Task-switching experiments have shown that the "switch cost" (poorer performance for task switches than for repetitions) is smaller when the probability of a switch is high (e.g., 0.75) than when it is low (e.g., 0.25). Some theoretical accounts explain this effect in terms of top-down control deployed in advance of the task cue ("pre-cue reconfiguration"). We tested such accounts by manipulating the time available before the onset of the cue (the response-cue interval, RCI), reasoning that top-down pre-cue reconfiguration requires time and therefore its effect should increase with RCI. Participants heard a man and a woman simultaneously speaking number words and categorised the number (< 5 vs. > 5) spoken by the voice specified by a pictorial gender-related cue presented at an RCI of 100 ms or 2,200 ms. The target voice switched with a probability of 0.25 or 0.75 (in separate sessions). In Experiment 1, RTs revealed a large effect of switch probability on the switch cost in the short RCI, which did not increase in the long RCI. Errors hinted at such an increase, but it did not receive clear statistical support and was disconfirmed by a direct and better powered replication in Experiment 2, which fully confirmed the RT pattern from Experiment 1. Thus, the effect of switch probability on the switch cost required little/no time following the response to emerge-it was already at full magnitude at a short RCI-challenging accounts that assume "phasic" deployment of top-down task-set control in advance of the cue.

Relationship Between the Parietal Cortex and Task Switching: Transcranial Direct Current Stimulation Combined with an Event-related Potential Study

Task switching refers to a set of cognitive processes involved in shifting attention from one task to another. In recent years, researchers have applied transcranial direct current stimulation (tDCS) to investigate the causal relationship between the parietal cortex and task switching. However, results from available studies are highly inconsistent. This may be due to the unclear understanding of the underlying mechanisms. Therefore, the current study utilized event-related potential (ERP) analysis to investigate the modulatory effects of tDCS on task-switching processes. Twenty-four subjects were recruited to perform both predictable and unpredictable parity/magnitude tasks under anodal (RA) and sham conditions. The results showed no significant changes in behavioral performance. However, marked tDCS-induced ERP changes were observed. Specifically, for the predictable task switching, compared with the sham condition, the target-N2 component occurred significantly earlier for switch trials than repeat trials under the RA condition in males, while no difference was found in females. For unpredictable task switching, under the sham condition, the P2 peak was significantly larger for switch trials compared with repeat trials, whereas this difference was not observed under the RA condition. These results indicated the causal relationship between the right parietal cortex and exogenous adjustment processes involved in task switching. Moreover, anodal tDCS over the right parietal cortex may lead to the manifestation of gender differences.

Effect of homeostatic pressure and circadian rhythm on the task-switching: Evidence from drift diffusion model and ERP

The effect of diurnal fluctuations on cognitive functions is widely studied, yet rare research has attempted to separate the role of two crucial processes underlying diurnal fluctuations: homeostatic pressure and circadian rhythm. The present study aimed to dissociate their effects by conducting a task-switching task in the morning, napping afternoon, and no-napping afternoon, respectively. Additionally, DDM and ERP were utilized to explore how these two processes differentially affect cognitive processes involved in task-switching. By a within-participant design, 35 healthy adults (20.03 ± 2.01 year-old, 14 males) with an intermediate-type chronotype were recruited in the current study. The results demonstrated that accumulated homeostatic pressure caused reduced accuracy, drift rate, and decision threshold. In the no-napping afternoon, P1 and P2 amplitudes were also decreased due to homeostatic pressure, whereas an afternoon nap could partially restore performance and neural activity. Conversely, the upward circadian rhythm in the afternoon exerted a compensatory effect, resulting in increases in N2 and P3 amplitudes. The findings highlight the disassociated impacts of homeostatic pressure and circadian rhythm on the cognitive processes involved in task-switching and further underscore the importance of considering diurnal variation in both scientific research and accident prevention.

Consequences of scarcity: the impact of perceived scarcity on executive functioning and its neural basis

Introduction

Previous studies have found a causal relationship between scarcity and the adverse impact it has on executive functioning. However, few studies have directly examined perceived scarcity, and cognitive flexibility (the third component of executive functions) has rarely been included.

Methods

Using a 2 (group: scarcity group vs. control group) × 2 (trial type: repeat trial vs. switch trial) mixed design, this study directly explored perceived scarcity's impact on cognitive flexibility and revealed its neural basis in the switching tasks. Seventy college students participated in this study through open recruitment in China. A priming task was used to induce perceived scarcity, thus exploring the impact of perceived scarcity on participants' performance in switching tasks and enabling the analysis of the neural activity of the brain, combined with electroencephalograph (EEG) technology.

Results

In terms of behavioral outcomes, perceived scarcity led to poorer performance and a greater switching cost of reaction time in the switching tasks. Regarding neural activity, perceived scarcity led to an increase in the amplitude of P3 differential wave (repeat trials minus switch trials) in the parietal cortex during the target-locked epochs in the switching tasks.

Discussion

Perceived scarcity can lead to changes in the neural activity of the brain regions related to executive functioning, resulting in a temporary decrease in cognitive flexibility. It may lead to individuals unable to adapt well to the changing environment, unable to quickly devote themselves to new tasks, and reduce work and learning efficiency in daily life.

Impaired proactive control in individuals with methamphetamine use disorder: Evidence from ERPs

BACKGROUND

Research suggests that methamphetamine use is associated with impaired cognitive control, which may contribute to impulsive drug use. Cognitive control is dynamically mediated by proactive and reactive control (reflecting various processing stages of cognitive control with different properties), and it is crucial to determine whether methamphetamine use impairs proactive and/or reactive control. To address this issue, we conducted an event-related potential (ERP) study to examine proactive and reactive control in individuals with methamphetamine use disorder (MUD).

METHODS

Abstinent individuals with MUD (n = 25) and healthy controls (HC, n = 27) completed a cued task-switching task while brain electrical activity was recorded. Cue- and target-locked ERP components modulated by task switching were linked to proactive and reactive control, respectively.

RESULTS

No behavioral differences between the groups were found. However, the HC group showed cue-locked switch-positivity (i.e., more positive amplitudes for switch than repeat trials) in both the early and late time windows, although the MUD group only showed late switch-positivity, which was smaller than the HC group. Independent of switch or congruent condition, the MUD group had smaller target-locked positivity than the HC group.

CONCLUSIONS

These findings suggest that individuals with MUD exhibit reduced proactive control and mobilize extra reactive control efforts to compensate. Our study contributes to a better understanding of cognitive control impairment in individuals with MUD and has implications for potential interventions.

Reconfiguration of response-set in task switching: Event-related potential evidence

In task switching, an interaction between task and response is often observed, with response repetition (RR) benefits in task-repeat trials and RR costs in task-switch trials. The theoretical accounts of the RR effect remain controversial, and neuroscience evidence is scarce. The present study utilized the event-related potentials (ERPs) method to explore the neural mechanism underlying the RR effect by adopting a cued task-switching paradigm. The ERP results revealed the interaction between task and response in the P3b time window, with a response switch positivity under task-repetition conditions and an RR positivity under task-switching conditions. In addition, there were RR positivity in the N2 irrespective of task transition and in the late component (LC, 550-600 ms) that only under the task repetition condition. On the individual level, the RR benefit positively correlated with the RR positivity in the LC, while the RR costs negatively correlated with RR positivity in the N2/P3 component. These results suggest that both response reconfiguration and episodic-retrieval make contributions to the RR effects, which were also discussed in terms of predictive model for a domain-general inference and learning of perceptual categories.

Investigating the involvement of cognitive control processes in innovative and adaptive creativity and their age-related changes

Introduction

Based on the two-factor model of creativity, two distinct types of creative problem solving can be differentiated: innovative ("do things differently") and adaptive ("do things better"). Flexible cognitive control is a crucial concept in connection with both general and specific styles of creativity: innovative problem-solving benefits from broader attention and flexible mental set shifting; while adaptive creativity relies on focused attention and persistent goal-oriented processes. We applied an informatively cued task-switching paradigm which is suitable for measuring different cognitive control processes and mechanisms like proactive and reactive control. We hypothesized that adaptive creativity is connected to effective proactive control processes, while innovative creativity is based on reactive task-execution. As we have found no previous evidence how age-related changes in cognitive control affects creative cognition; we also examined the effect of healthy aging on different problem-solving styles in an explorative way.

Methods

Our participants, 37 younger (18-30 years) and 37 older (60-75 years) adults, were divided into innovative and adaptive creative groups according to the Torrance Test of Creative Thinking's Figural Subtest (Hungarian version).

Results

Our results showed that among younger adults the adaptively creative group had larger cue-locked CNV component (effective preparatory activity connected to proactive control), while the innovatively creative group had a larger target-locked P3b component (effective target evaluation and categorization in line with reactive control) which supports a functional difference in the two creative styles. By contrast, in older adults innovative problem-solving showed larger mixing costs (less effective maintenance and selection of task sets), and the lack of trial type effect on target-locked N2b (target-induced goal reactivation and less effective conflict resolution); while adaptive problem-solving caused them to make fewer errors (accuracy-oriented behavior).

Discussion

All in all, innovative and adaptive creativity is based on distinct cognitive control mechanisms in both age-groups, but their processing level is affected by age-related changes.

The Effect of Code-Switching Experience on the Neural Response Elicited to a Sentential Code Switch

Switching between languages, or codeswitching, is a cognitive ability that multilinguals can perform with ease. This study investigates whether codeswitching during sentence reading affects early access to meaning, as indexed by the robust brain response called the N400. We hypothesize that the brain prioritizes the meaning of the word during comprehension with codeswitching costs emerging at a different stage of processing. Event-related potentials (ERPs) were recorded while Spanish-English balanced bilinguals (n = 24) read Spanish sentences containing a target noun that could create a semantic violation, codeswitch or both. Self-reported frequency of daily codeswitching was used as a regressor to determine if the cost of reading a switch is modulated by codeswitching experience. A robust N400 to semantic violations was followed by a late positive component (LPC). Codeswitches modulated the left anterior negativity (LAN) and LPC, but not the N400, with codeswitched semantic violations resulting in a sub-additive interaction. Codeswitching experience modulated the LPC, but not the N400. The results suggest that early access to semantic memory during comprehension happens independent of the language in which the words are presented. Codeswitching affects a separate stage of comprehension with switching experience modulating the brain's response to experiencing a language switch.

Cognitive control is modulated by hierarchical complexity of task switching: An event-related potential study

The study aimed to explore the effect of hierarchical complexity on task switching. The participants (n = 36) were asked to perform a magnitude or parity judgement on digits (1-9) in the hierarchical simple or complex block. In the simple block, participants made a numerical judgement on the presented digit (1-9) in each trial, whereas in the complex block, they had to first identify whether the digit in the current trial belonged to a predefined category (e.g., whether it was an even number), then perform a numerical judgment or not respond. The behavioural results revealed a significant interaction between hierarchical complexity and transition type (repeat vs. switch), with greater switch cost in the complex than in the simple block. Event-related potentials (ERPs) locked in the cue stage did not reveal this interaction, whereas the ERPs locked in the target stage revealed this interaction during the N2 and P3 time windows, with a larger switch negativity (switch minus repeat) in the complex than in the simple block. These findings demonstrate that an increase in hierarchical complexity triggers increased reactive control in the inhibition of the old task-set and reconfiguration of the new task-set during task switching.

Cognitive Neural Mechanism of Backward Inhibition and Deinhibition: A Review

Task switching is one of the typical paradigms to study cognitive control. When switching back to a recently inhibited task (e.g., “A” in an ABA sequence), the performance is often worse compared to a task without N-2 task repetitions (e.g., CBA). This difference is called the backward inhibitory effect (BI effect), which reflects the process of overcoming residual inhibition from a recently performed task (i.e., deinhibition). The neural mechanism of backward inhibition and deinhibition has received a lot of attention in the past decade. Multiple brain regions, including the frontal lobe, parietal, basal ganglia, and cerebellum, are activated during deinhibition. The event-related potentials (ERP) studies have shown that deinhibition process is reflected in the P1/N1 and P3 components, which might be related to early attention control, context updating, and response selection, respectively. Future research can use a variety of new paradigms to separate the neural mechanisms of BI and deinhibition.

Proactive and reactive control differ between task switching and response rule switching: Event-related potential evidence

The distinction between task-switching (T-switch) and response-rule switching (RR-switch) has been reported in previous studies. However, it is unclear whether the neural correlates of proactive and reactive control differ between T-switch and RR-switch. In this study, a modified cue-target task was adopted. When the cue in the current trial differed from that in the preceding trial in shape (or color), the participants had to perform a T-switch (or RR-switch). Otherwise, they performed the same task following the same response rule. The behavioral results showed that the switch cost was greater for the RR-switch than for the T-switch. The event-related potential results indicated that (1) for cues, the switch-positivity in the late positive component (LPC) (500-800 ms) was more enhanced for the RR-switch than for the T-switch over the central to parietal regions, reflecting increased proactive control for the RR-switch compared with the T-switch; (2) for targets, the P3 amplitude was more attenuated in the RR-switch than the T-switch over the central and parietal regions, reflecting increased reactive control for the RR-switch; and (3) under the T-switch, the switch-positivity in the cue-LPC was negatively correlated with accuracy cost, while under the RR-switch, the switch negativity in the target-P3 was positively correlated with the reaction time cost. These findings suggest that similar proactive and reactive control are recruited in the T-switch and RR-switch, whereas cognitive control efforts clearly differ between them, perhaps due to different sub-processes.

Potential Diffusion Tensor Imaging Biomarkers for Elucidating Intra-Individual Age-Related Changes in Cognitive Control and Processing Speed

Cognitive aging, especially cognitive control, and processing speed aging have been well-documented in the literature. Most of the evidence was reported based on cross-sectional data, in which inter-individual age effects were shown. However, there have been some studies pointing out the possibility of overlooking intra-individual changes in cognitive aging. To systematically examine whether age-related differences and age-related changes might yield distinctive patterns, this study directly compared cognitive control function and processing speed between different cohorts versus follow-up changes across the adult lifespan. Moreover, considering that cognitive aging has been attributed to brain disconnection in white matter (WM) integrity, this study focused on WM integrity via acquiring diffusion-weighted imaging data with an MRI instrument that are further fitted to a diffusion tensor model (i.e., DTI) to detect water diffusion directionality (i.e., fractional anisotropy, FA; mean diffusivity, MD; radial diffusivity, RD; axial diffusivity, AxD). Following data preprocessing, 114 participants remained for further analyses in which they completed the two follow-up sessions (with a range of 1-2 years) containing a series of neuropsychology instruments and computerized cognitive control tasks. The results show that many significant correlations between age and cognitive control functions originally shown on cross-sectional data no longer exist on the longitudinal data. The current longitudinal data show that MD, RD, and AxD (especially in the association fibers of anterior thalamic radiation) are more strongly correlated to follow-up aging processes, suggesting that axonal/myelin damage is a more robust phenomenon for observing intra-individual aging processes. Moreover, processing speed appears to be the most prominent cognitive function to reflect DTI-related age (cross-sectional) and aging (longitudinal) effects. Finally, converging the results from regression analyses and mediation models, MD, RD, and AxD appear to be the representative DTI measures to reveal age-related changes in processing speed. To conclude, the current results provide new insights to which indicator of WM integrity and which type of cognitive changes are most representative (i.e., potentially to be neuroimaging biomarkers) to reflect intra-individual cognitive aging processes.

Reconfiguration of response rule is more difficult than that of task goal: Behavior and electrophysiological evidence

Previous studies have investigated the neural mechanisms underlying cognitive control by using the task-switching paradigm, but differentiation from response rule switching (RR-switch) remains poorly explored. In this study, a partial voluntary task-switching (VTS) paradigm was used to explore the electrophysiological differences between task switching (T-switch) and RR-switching. Participants were sequentially presented with Arabic numerals colored red or green. If the color in the current trial was the same as that in the previous trial, the participants had to perform the same task following the same response rule. Otherwise, they had to voluntarily switch tasks (e.g., from parity task to magnitude task) or switch response rules (e.g., from "pressing F for odd and J for even number' to 'pressing J for odd and F for even number"). The behavioral results indicated that RR-switch was infrequently selected, and the performance was less efficient than that of the T-switch. Event-related potential results showed that both T- and RR-switches elicited a larger switch-positivity in the P2 and P3 time windows than that in the repeat condition. Switch-positivity was larger for RR-switch than for T-switch over the frontal sites, suggesting that more attention and cognitive resources were required to update information for the RR-switch than for the T-switch. These findings suggest that in the VTS, the hierarchical relationship between task goals and response rules is relatively loose, resulting in the neural disassociation of task reconfiguration and response change.

Neural markers of proactive and reactive cognitive control are altered during walking: A Mobile Brain-Body Imaging (MoBI) study

The processing of sensory information and the generation of motor commands needed to produce coordinated actions can interfere with ongoing cognitive tasks. Even simple motor behaviors like walking can alter cognitive task performance. This cognitive-motor interference (CMI) could arise from disruption of planning in anticipation of carrying out the task (proactive control) and/or from disruption of the execution of the task (reactive control). In young healthy adults, walking-induced interference with behavioral performance may not be readily observable because flexibility in neural circuits can compensate for the added demands of simultaneous loads. In this study, cognitive-motor loads were systematically increased during cued task-switching while underlying neurophysiologic changes in proactive and reactive mechanisms were measured. Brain activity was recorded from 22 healthy young adults using 64-channel electroencephalography (EEG) based Mobile Brain/Body Imaging (MoBI) as they alternately sat or walked during performance of cued task-switching. Walking altered neurophysiological indices of both proactive and reactive control. Walking amplified cue-evoked late fontal slow waves, and reduced the amplitude of target-evoked fronto-central N2 and parietal P3. The effects of walking on evoked neural responses systematically increased as the task became increasingly difficult. This may provide an objective brain marker of increasing cognitive load, and may prove to be useful in identifying seemingly healthy individuals who are currently able to disguise ongoing degenerative processes through active compensation. If, however, degeneration continues unabated these people may reach a compensatory limit at which point both cognitive performance and control of coordinated actions may decline rapidly.

Serial or parallel proactive control of components of task-set? A task-switching investigation with concurrent EEG and eye-tracking

Among the issues examined by studies of cognitive control in multitasking is whether processes underlying performance in the different tasks occur serially or in parallel. Here we ask a similar question about processes that pro-actively control task-set. In task-switching experiments, several indices of task-set preparation have been extensively documented, including anticipatory orientation of gaze to the task-relevant location (an unambiguous marker of reorientation of attention), and a positive polarity brain potential over the posterior cortex (whose functional significance is less well understood). We examine whether these markers of preparation occur in parallel or serially, and in what order. On each trial a cue required participants to make a semantic classification of one of three digits presented simultaneously, with the location of each digit consistently associated with one of three classification tasks (e.g., if the task was odd/even, the digit at the top of the display was relevant). The EEG positivity emerged following, and appeared time-locked to, the anticipatory fixation on the task-relevant location, which might suggest serial organisation. However, the fixation-locked positivity was not better defined than the cue-locked positivity; in fact, for the trials with the earliest fixations the positivity was better time-locked to the cue onset. This is more consistent with (re)orientation of spatial attention occurring in parallel with, but slightly before, the reconfiguration of other task-set components indexed by the EEG positivity.

Dissociable theta networks underlie the switch and mixing costs during task switching

During task‐switching paradigms, both event‐related potentials and time‐frequency analyses show switch and mixing effects at frontal and parietal sites. Switch and mixing effects are associated with increased power in broad frontoparietal networks, typically stronger in the theta band (~4–8 Hz). However, it is not yet known whether mixing and switch costs rely upon common or distinct networks. In this study, we examine proactive and reactive control networks linked to task switching and mixing effects, and whether strength of connectivity in these networks is associated with behavioural outcomes. Participants (n = 197) completed a cued‐trials task‐switching paradigm with concurrent electroencephalography, after substantial task practice to establish strong cue‐stimulus–response representations. We used inter‐site phase clustering, a measure of functional connectivity across electrode sites, to establish cross‐site connectivity from a frontal and a parietal seed. Distinct theta networks were activated during proactive and reactive control periods. During the preparation interval, mixing effects were associated with connectivity from the frontal seed to parietal sites, and switch effects with connectivity from the parietal seed to occipital sites. Lateralised occipital connectivity was common to both switch and mixing effects. After target onset, frontal and parietal seeds showed a similar pattern of connectivity across trial types. These findings are consistent with distinct and common proactive control networks and common reactive networks in highly practised task‐switching performers.

Two-Year Follow-Up Study of the Relationship Between Brain Structure and Cognitive Control Function Across the Adult Lifespan

Age-related decline in cognitive control and general slowing are prominent phenomena in aging research. These declines in cognitive functions have been shown to also involve age-related decline in brain structure. However, most evidence in support of these associations is based on cross-sectional data. Therefore, the aim of this study is to contrast cross-sectional and longitudinal analyses to re-examine if the relationship between age-related brain structure and cognitive function are similar between the two approaches. One hundred and two participants completed two sessions with an average interval of 2 years. All participants were assessed by questionnaires, a series of cognitive tasks, and they all underwent neuroimaging acquisition. The main results of this study show that the majority of the conclusions regarding age effect in cognitive control function and processing speed in the literature can be replicated based on the cross-sectional data. Conversely, when we followed up individuals over an average interval of 2 years, then we found much fewer significant relationships between age-related change in gray matter structure of the cognitive control network and age-related change in cognitive control function. Furthermore, there was no "initial age" effect in the relationships between age-related changes in brain structure and cognitive function. This finding suggests that the "aging" relationship between brain structure and cognitive function over a short period of time are independent of "initial age" difference at time point 1. The result of this study warrants the importance of longitudinal research for aging studies to elucidate actual aging processes on cognitive control function.

Response variations can promote the efficiency of task switching: Electrophysiological evidence

Previous studies have investigated sequence effect on task switching and found that increased cognitive control in preceding trials would transfer to the current trial. However, it remains unclear whether response variations during task repetition can enhance cognitive control and promote task switching. In the present study, we designed two sequence contexts, the response-change (r-change) and response-repeat (r-repeat) contexts, by adopting a classical task-switching paradigm in which participants were asked to make an odd-even or large-small judgment of the presented digit. The only difference between the two sequence contexts was whether responses varied frequently during task repetition. Behavioral results showed that the r-change context induced smaller switch costs and higher accuracy for task switching than the r-repeat context. Event-related potential (ERP) results revealed (1) the effect of context on N2 amplitudes, with greater N2 in the r-change context than the r-repeat context at frontal-central regions; (2) the interaction between context and transition type during the stimulus-locked P3 component, with a marked context effect for the task-switch trials; (3) non-significant context effect on task switching during the response-locked P3 component. These findings suggest that response variations during a sequence of task-repeat trials can trigger the increase in cognitive control that promotes the efficiency of followed task switching.

Task Switching and the Role of Motor Reprogramming in Parietal Structures

Human behaviour amazes with extraordinary flexibility and the underlying neural mechanisms have often been studied using task switching. Despite extensive research, the relative importance of "cognitive" and "motor" aspects during switching is unclear. In the current study we examine this question combining EEG analysis techniques and source localization to examine whether the selection of the response, or processes during the execution of the response, contribute most to switching effects. A clear dissociation was observed in the signal decomposition, since codes relating to motor aspects play a significant role in task switching and the scope of the switching costs. This was not the case for signals that denote reaction selection or decision processes that respond to selection or basic stimulus processing codes. On a functional neuroanatomical level, these modulations in motor processes showed a clear temporal sequence in that motor codes are processed primarily in superior parietal regions (Brodman area 7) and only then in premotor regions (Brodman area 6). The observed modulations may reflect motor reprogramming processes. The study shows how EEG signal analysis in combination with brain mapping methods can inform debates on theories of human cognitive flexibility.

Neural electrophysiological mechanism of joint hierarchical rule shifting: an event-related potential study

Although previous studies have explored the brain mechanism by which an individual independently accomplishes task switching or rule shifting with different hierarchical structures, electrophysiological evidence indicating that two actors cooperate to complete the hierarchical rule shift remains unclear. This study adopts a modified joint hierarchical rule shifting paradigm in which one actor judged the parity task and the other decided the magnitude task. Results demonstrated that cues in high- and low-shift conditions elicited larger P2 amplitudes and that low-shift had a larger P3 amplitude than high-shift. Results further indicated that participants required more attention resources to ascertain who would make a judgment for the current trial and that low hierarchical features were superior in reconfiguring changed rules. Regarding the target, the high-shift condition evoked smaller P2 and larger N2 amplitudes when compared to low-shift and repeat conditions, whereas when compared to high- and low-shifts, the repeat condition elicited a larger P3 amplitude. The findings revealed that participants required more control resources to process the varied features and that repeat condition required the least cognitive resources to update rules. Thus, participants had different process patterns between cues and targets when cooperating with their co-actors.

Impaired set-shifting in drug-naïve patients with borderline personality disorder: an event-related potentials study

BACKGROUND

Neurocognitive impairments might play a key role in the development of Borderline Personality Disorder (BPD), however, the pathophysiological mechanism underlying cognitive impairment of BPD is largely unknown. This study was aimed to examine the electrophysiological mechanism of deficits in set-shifting processing in patients with BPD.

METHODS

Twenty-seven drug-naïve patients with BPD and twenty-four healthy controls were recruited. Demographic variables and clinical characteristics of all subjects were collected. Behavioral data and event-related potentials (ERPs) were recorded when subjects were performing the task-switching paradigm, which was applied to investigate the set-shifting function. The P2, N2 and P3 components in the task-switching paradigm would be analyzed.

RESULTS

Patients with BPD had significantly higher level of impulsivity, depression and anxiety than healthy controls. When performing the switching task, the BPD group had lower P2 amplitude and higher N2 amplitude than the control group. In the BPD group, the P2 latency at Fz electrode in repeat task was correlated positively with the level of depression, and P2 latency at Pz electrode in repeat task and switch task both had significantly negative relationships with the the level of anxiety.

LIMITATIONS

This cross-sectional designed study did not clarify the causal relationship of the electrophysiological characteristics and the development of BPD.

CONCLUSIONS

Patients with BPD might have abnormal brain activities when overcoming the inhibition of current task and inhibiting the effects of prior task, and their top-down control function might be impaired. These findings provide some useful clues for the underlying pathophysiological mechanism of BPD.

More change in task repetition, less cost in task switching: Behavioral and event-related potential evidence

Previous studies have shown that the probability of task switching can vary the level of cognitive control and modulate the size of switch costs. However, it is unclear whether switch costs would be affected by a task-repetition context formed by varying the degree of response (and task-relevant stimulus property) change within the task repetition sequences while the probability of task switching remains constant. In the present study, participants were presented with a string of digits (e.g., ②②②). Basing on stimulus color, they were required to indicate either the presented digit, or the number of presented digits. Before task switching, stimulus and response in consecutive task-repeat trials varied more or less frequently. Behavioral results showed that the frequent-change context elicited smaller switch costs than the rare-change context. Event-related potential (ERP) results indicated that: (1) the frequent-change context evoked greater fronto-central N2 amplitudes for both task-repeat and task-switch trials, implying that cognitive control increased due to the variation of stimulus and response associations; (2) for the task switch trials, smaller P300 amplitudes were evoked in the frequent-change context than the rare-change context, reflecting the promoted task-set reconfiguration. These findings suggest that, the more change in stimulus and response during task repetition, the higher the overall level of cognitive control and the higher efficiency of task-switching.

Training and Transfer of Cue Updating in Older Adults Is Limited: Evidence From Behavioral and Neuronal Data

Cognitive control processes, such as updating task-relevant information while switching between multiple tasks, are substantially impaired in older adults. However, it has also been shown that these cognitive control processes can be improved by training interventions, e.g., by training in task switching. Here, we applied an event-related potential (ERP) approach to identify whether a cognitive training improves task-preparatory processes such as updating of relevant task goals. To do so, we applied a pretest-training-posttest design with eight training sessions. Two groups of older adults were either trained in task switching (treatment group) or in performing single tasks (control group) and we compared their performance to a group of untrained younger adults. To foster cue updating in the treatment group, we applied a cue-based switching task in which the two task cues were randomly selected prior to target presentation so that participants had time to prepare for the upcoming task. In contrast, the control group also received task cues but those were redundant as only one task had to be performed. We also examined whether training in cue updating during task switching can be transferred to a similar cognitive control task measuring updating of context information, namely a modified version of the AX-Continuous Performance Task (AX-CPT). The results revealed training-specific improvements in task switching, that is, a larger improvement in blocks requiring switching in comparison to single tasks at the behavioral level. In addition, training specific-effects were also found at the neuronal level. Older adults trained in cue updating while switching showed a reduction in mixing costs in the cue-related P3, indicating an improvement in preparatory updating processes. Additionally, P3 topography changed with training from a very broad to a parietally focused scalp distribution similar to the one found in younger adults. However, we did not obtain training-specific improvements in context updating in the AX-CPT neither at the behavioral level nor at the neuronal level. Results are discussed in the context of the ongoing debate on whether transfer of cognitive training improvements is possible.

PEP Does Not Dispense with but Implements Task-Set Reconfiguration. Can It Handle Phenomena More Diagnostic of Endogenous Control?

Invited commentary on Schmidt, Liefooghe, and De Houwer (2020) An episodic model of task switching effects: erasing the homunculus from memory. Journal of Cognition.

Using the perceptual past to predict the perceptual future influences the perceived present - A novel ERP paradigm

The information available through our senses is noisy, incomplete, and to varying degrees ambiguous. The perceptual system must create stable and reliable percepts out of this restricted information. It solves this perceptual inference problem by integrating memories of previous percepts and making predictions about the perceptual future.

Using ambiguous figures and a new experimental approach, we studied whether generating predictions based on regularities in the past affects processing of the present and how this is done. Event-related potentials (ERPs) were measured to investigate whether a highly regular temporal context of either ambiguous or unambiguous stimulus variants differently affects processing of a current stimulus and/or task execution. Further, we tested whether symbolic announcements about the immediate perceptual future can replace the past experience of regularities as a source for making predictions. Both ERP and reaction time varied as a function of stimulus ambiguity in the temporal context of a present stimulus. No such effects were found with symbolic announcements.

Our results indicate that predictions about the future automatically alter processing of the present, even if the predictions are irrelevant for the present percept and task. However, direct experiences of past regularities are necessary for predicting the future whereas symbolic information about the future is not sufficient.

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.

Age-Related Differences Between Young and Old Adults: Effects of Advance Information on Task Switching

In this study we investigated the effects of advance information on task switching in young and old adults, using two forms of advance information (memory-based and cue-based) and a no advance information task. We compared 19 healthy young and 19 healthy older adults in terms of their behavioral performance and neural correlates under these three task-switching paradigms. We observed a significant difference in mixing cost between the two age groups. There was no switch cost group difference on the memory-based and cue-based tasks, but older adults showed a larger switch cost than younger adults on the no advance information task. On evoked potential measures, there was no group effect in P3 cue-locked positivity; but there was, a frontal shift of the target-locked P3, indexed as reactive control, among older adults. We observed an increased target-locked P3 in the no-information paradigm compared with the cue-based and memory-based paradigms in both groups. Task cue facilitated advance preparation and proactive control under the cue-based paradigm in both groups. Age-related decline and difficulty in control processes required for task goal maintenance were apparent among the older adults.

Neural Dynamics of Cognitive Control in Various Types of Incongruence

Conflict-control is a core function of cognitive control. Although numerous studies have considered cognitive control to be domain-general, the shared and distinct brain responses to different types of incongruence or conflict remain unclear. Using a hybrid flanker task, the present study explored the temporal dynamics of brain activation to three types of incongruence: flanker interference, rule-based response switch (rule-switch), and action-based response switch (response-alternation). The results showed that: (1) all three types of incongruence evoked larger N2 amplitudes than the congruent condition in the frontal region, with the N2 amplitudes and topographical distribution of the N2 effect differing between the different types of incongruence; and (2) in the P300 time window, the flanker interference condition yielded the most delayed P300 latency, whereas the rule-switch and response-alternation conditions yielded smaller P300 amplitudes with a longer interval from P300 peak to a keypress. These findings suggest that different types of incongruence are first monitored similarly by the cognitive control system and then resolved differently.

Connecting EEG signal decomposition and response selection processes using the theory of event coding framework

The neurophysiological mechanisms underlying the integration of perception and action are an important topic in cognitive neuroscience. Yet, connections between neurophysiology and cognitive theoretical frameworks have rarely been established. The theory of event coding (TEC) details how perceptions and actions are associated (bound) in a common representational domain (the “event file”), but the neurophysiological mechanisms underlying these processes are hardly understood. We used complementary neurophysiological methods to examine the neurophysiology of event file processing (i.e., event‐related potentials [ERPs], temporal EEG signal decomposition, EEG source localization, time‐frequency decomposition, EEG network analysis). We show that the P3 ERP component and activity modulations in inferior parietal regions (BA40) reflect event file binding processes. The relevance of this parietal region is corroborated by source localization of temporally decomposed EEG data. We also show that temporal EEG signal decomposition reveals a pattern of results suggesting that event file processes can be dissociated from pure stimulus and response‐related processes in the EEG signal. Importantly, it is also documented that event file binding processes are reflected by modulations in the network architecture of theta frequency band activity. That is, when stimulus–response bindings in event files hamper response selection this was associated with a less efficient theta network organization. A more efficient organization was evident when stimulus–response binding in event files facilitated response selection. Small‐world network measures seem to reflect event file processing. The results show how cognitive‐theoretical assumptions of TEC can directly be mapped to the neurophysiology of response selection.

Neuro-dynamics of executive control in bilingual language switching: An MEG study

Bilinguals have a remarkable ability to juggle two languages. A central question in the field is concerned with the control mechanisms that enable bilinguals to switch language with ease. Theoretical models and neuroimaging evidence suggest that a range of control processes are at play during language switching, and their underlying neural mechanisms are closely related to executive function. What remains unclear is when these control processes are engaged in language switching. In this study, we used magnetoencephalography (MEG) to examine the brain activity while unbalanced Mandarin-English bilinguals performed a digit-naming task with cued language switching. Following presentation of the language cue, an asymmetrical switch effect was observed in the left inferior frontal gyrus (IFG), where switch-related increase in evoked brain activity was larger for switching into the non-dominant language. Following presentation of the naming target, evoked brain activity in the right IFG was larger when naming was required in the non-dominant language compared to the dominant language. We conclude that control processes take place in two stages during language switching, with the left IFG resolving interference following cue presentation and the right IFG inhibiting competing labels following target presentation.

Altered proactive control in adults with ADHD: Evidence from event-related potentials during cued task switching

Cognitive control has two distinct modes - proactive and reactive (Braver, T. S. (2012). The variable nature of cognitive control: a dual mechanisms framework. Trends in Cognitive Sciences, 16(2), 105-112). ADHD has been associated with cognitive control impairments. However, studies have mainly focused on reactive control and not proactive control. Here we investigated neural correlates of proactive and reactive cognitive control in a group of adults with ADHD versus healthy controls by employing a cued switching task while cue informativeness was manipulated and EEG recorded. On the performance level, only a trend to generally slower responding was found in the ADHD group. Cue-locked analyses revealed an attenuated informative-positivity - a differential component appearing when contrasting informative with non-informative alerting cues - and potentially altered lateralisation of the switch-positivity - evident in the contrast between switch and repeat trials for informative cues - in ADHD. No difference in target-locked activity was found. Our results indicate altered proactive rather than reactive control in adults with ADHD, evidenced by less use of cued advance information and abnormal preparatory processes for upcoming tasks.

Revisiting the relationship between the P3b and working memory updating

The P3b is an extensively studied neurophysiological phenomenon that is predominantly explained in the cognitive neuroscience literature as reflecting context updating, presumably in working memory (WM). Despite the prevalence and influence of the context updating hypothesis, direct empirical support for the role of WM updating in eliciting the P3b is still missing. The present study was designed to address the empirical gap in understanding the functional role of P3b in general, and specifically in relation to WM updating. A mass-univariate approach was used to test the unique contribution of WM updating, categorization, and stimulus probability to the P3b. The results indicated that the P3b is only modulated by the categorization process, a finding that challenges the WM updating hypothesis. Taken together these results, we suggest that the P3b reflects a WM guided target identification mechanism, which operates as part of a goal-directed learning strategy.

Common and distinct neural correlates of dual-tasking and task-switching: a meta-analytic review and a neuro-cognitive processing model of human multitasking

Although there are well-known limitations of the human cognitive system in performing two tasks simultaneously (dual-tasking) or alternatingly (task-switching), the question for a common vs. distinct neural basis of these multitasking limitations is still open. We performed two Activation Likelihood Estimation meta-analyses of neuroimaging studies on dual-tasking or task-switching and tested for commonalities and differences in the brain regions associated with either domain. We found a common core network related to multitasking comprising bilateral intraparietal sulcus (IPS), left dorsal premotor cortex (dPMC), and right anterior insula. Meta-analytic contrasts revealed eight fronto-parietal clusters more consistently activated in dual-tasking (bilateral frontal operculum, dPMC, and anterior IPS, left inferior frontal sulcus and left inferior frontal gyrus) and, conversely, four clusters (left inferior frontal junction, posterior IPS, and precuneus as well as frontomedial cortex) more consistently activated in task-switching. Together with sub-analyses of preparation effects in task-switching, our results argue against purely passive structural processing limitations in multitasking. Based on these findings and drawing on current theorizing, we present a neuro-cognitive processing model of multitasking.

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.

When repetitive mental sets increase cognitive flexibility in adolescent obsessive-compulsive disorder

BACKGROUND

A major facet of obsessive-compulsive disorder (OCD) is cognitive inflexibility. However, sometimes, cognitive flexibility can be needed to reuse recently abandoned mental sets. Therefore, cognitive flexibility can in certain cases be useful to reinstate some form of rigid, repetitive behavior characterizing OCD. We test the counterintuitive hypothesis that under such circumstances, cognitive flexibility is better in OCD patients than controls.

METHODS

We examined N = 20 adolescent OCD patients and N = 22 controls in a backward inhibition (BI) paradigm. This was combined with event-related potential (ERP) recordings and source localization. The BI effect describes the cost of overcoming the inhibition of a recently abandoned mental set that is relevant again. Therefore, a strong BI effect is disadvantageous for cognitive flexibility.

RESULTS

Compared to controls, OCD patients revealed a smaller backward inhibition effect. The EEG data revealed larger P1 amplitudes in backward inhibition trials in the OCD group, which was due to activation differences in the inferior frontal gyrus (BA47). The severity of clinical symptoms predicted these neurophysiological modulations. The power of the observed effects was about 95%.

CONCLUSIONS

The study shows that cognitive flexibility can be better in OCD than controls. This may be the case in situations where superior abilities in the reactivation of repeating mental sets and difficulties to process new ones coincide. This may be accomplished by intensified inhibitory control mechanisms. The results challenge the view on OCD, since OCD is not generally associated with cognitive inflexibility.

Task-Switching Training and Transfer

Abstract. We used task-switching (TS) paradigms to study how cognitive training can compensate age-related cognitive decline. Thirty-nine young (age span: 18–25 years) and 40 older (age span: 60–75 years) women were assigned to training and control groups. The training group received 8 one-hour long cognitive training sessions in which the difficulty level of TS was individually adjusted. The other half of the sample did not receive any intervention. The reference task was an informatively cued TS paradigm with nogo stimuli. Performance was measured on reference, near-transfer, and far-transfer tasks by behavioral indicators and event-related potentials (ERPs) before training, 1 month after pretraining, and in case of older adults, 1 year later. The results showed that young adults had better pretraining performance. The reference task was too difficult for older adults to form appropriate representations as indicated by the behavioral data and the lack of P3b components. But after training older adults reached the level of performance of young participants, and accordingly, P3b emerged after both the cue and the target. Training gain was observed also in near-transfer tasks, and partly in far-transfer tasks; working memory and executive functions did not improve, but we found improvement in alerting and orienting networks, and in the execution of variants of TS paradigms. Behavioral and ERP changes remained preserved even after 1 year. These findings suggest that with an appropriate training procedure older adults can reach the level of performance seen in young adults and these changes persist for a long period. The training also affects the unpracticed tasks, but the transfer depends on the extent of task similarities.

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.