Pre-stimulus EEG effects related to response speed, task switching and upcoming response hand

Electrophysiological evidence of discontinuities in the propagation of lexical decision processes across the motor hierarchy

This research assessed the propagation of decisional effects across multiple electrophysiological indexes related to motor-response implementation within a lexical decision task, a paradigmatic case of a 2-alternative choice task on linguistic stimuli. By co-registering electroencephalographic and electromyographic data, we focused on the lexicality effect (i.e., the difference between responses to words and nonwords), and we tracked its influence across indexes of motor-response planning (indexed by effector-selective lateralization of beta-frequency desynchronizations), programming (indexed by the lateralized readiness potential) and execution (indexed by the chronometric durations of muscular responses). In addition, we explored corticomuscular coherence as the potential physiological underpinning of a continuous mapping of information between stimulus evaluation and response channels. The results revealed lexicality effects only on indexes of motor planning and execution, with no reliable involvement of the other measures. This pattern is discussed with reference to the hypothesis of multiple decisional components exerting different influences across the motor-hierarchy.

How Intermittent Brain States Modulate Neurophysiological Processes in Cognitive Flexibility

Cognitive flexibility is an essential facet of everyday life, for example, when switching between different tasks. Neurophysiological accounts on cognitive flexibility have often focused on the task switch itself, disregarding preceding processes and the possible impact of "brain states" before engaging in cognitive flexibility. In a combined working memory/task-switching paradigm, we examined how neuronal processes during cognitive flexibility are interrelated to preceding neuronal processes across time and brain regions in a sample of n = 42 healthy adults. The interrelation of alpha- and theta-band-related processes over brain states ahead and during response selection was investigated on a functional neuroanatomical level using EEG-beamforming. The results showed that response selection processes (reflected by theta-band activity) seem to be strongly connected to "idling" and preparatory brain activity states (in both the theta- and alpha-band). Notably, the superior parietal cortex seems to play a crucial role by assembling alpha-band-related inhibitory processes from the rule- and goal-based actions during "idling" brain states, namely, short-term maintenance of rules (temporal cortex), task-set reconfiguration (superior frontal/precentral regions), and perceptual control (occipital cortex). This information is further relayed to response selection processes associated with theta-band activity. Notably, when the task has to be switched, theta-band activity in the superior frontal gyrus indicates a need for cognitive control in the "idling" brain state, which also seems to be relayed by BA7. The results indicate the importance of brain activity states ahead of response selection processes for cognitive flexibility.

Research on Top Archer’s EEG Microstates and Source Analysis in Different States

The electroencephalograph (EEG) microstate is a method used to describe the characteristics of the EEG signal through the brain scalp electrode potential’s spatial distribution; as such, it reflects the changes in the brain’s functional state. The EEGs of 13 elite archers from China’s national archery team and 13 expert archers from China’s provincial archery team were recorded under the alpha rhythm during the resting state (with closed eyes) and during archery aiming. By analyzing the differences between the EEG microstate parameters and the correlation between these parameters with archery performance, as well as by combining our findings through standardized low-resolution brain electromagnetic tomography source analysis (sLORETA), we explored the changes in the neural activity of professional archers of different levels, under different states. The results of the resting state study demonstrated that the duration, occurrence, and coverage in microstate D of elite archers were significantly higher than those of expert archers and that their other microstates had the greatest probability of transferring to microstate D. During the archery aiming state, the average transition probability of the other microstates transferring to microstate in the left temporal region was the highest observed in the two groups of archers. Moreover, there was a significant negative correlation between the duration and coverage of microstates in the frontal region of elite archers and their archery performance. Our findings indicate that elite archers are more active in the dorsal attention system and demonstrate a higher neural efficiency during the resting state. When aiming, professional archers experience an activation of brain regions associated with archery by suppressing brain regions unrelated to archery tasks. These findings provide a novel theoretical basis for the study of EEG microstate dynamics in archery and related cognitive motor tasks, particularly from the perspective of the subject’s mental state.

From Expert to Elite? — Research on Top Archer’s EEG Network Topology

It is not only difficult to be a sports expert but also difficult to grow from a sports expert to a sports elite. Professional athletes are often concerned about the differences between an expert and an elite and how to eventually become an elite athlete. To explore the differences in brain neural mechanism between experts and elites in the process of motor behavior and reveal the internal connection between motor performance and brain activity, we collected and analyzed the electroencephalography (EEG) findings of 14 national archers and 14 provincial archers during aiming and resting states and constructed the EEG brain network of the two archer groups based on weighted phase lag index; the graph theory was used to analyze and compare the network characteristics via local network and global network topologies. The results showed that compared with the expert archers, the elite archers had stronger functional coupling in beta1 and beta2 bands, and the difference was evident in the frontal and central regions; in terms of global characteristics of brain network topology, the average clustering coefficient and global efficiency of elite archers were significantly higher than that of expert archers, and the eigenvector centrality of expert archers was higher; for local characteristics, elite archers had higher local efficient; and the brain network characteristics of expert archers showed a strong correlation with archery performance. This suggests that compared with expert archers, elite archers showed stronger functional coupling, higher integration efficiency of global and local information, and more independent performance in the archery process. These findings reveal the differences in brain electrical network topologies between elite and expert archers in the archery preparation stage, which is expected to provide theoretical reference for further training and promotion of professional athletes.

Disruptions of Sustained Spatial Attention Can Be Resistant to the Distractor's Prior Reward Associations

Attention can be involuntarily biased toward reward-associated distractors (value-driven attentional capture, VDAC). Yet past work has primarily demonstrated this distraction phenomenon during a particular set of circumstances: transient attentional orienting to potentially relevant stimuli occurring in our visual environment. Consequently, it is not well-understood if reward-based attentional capture can occur under other circumstances, such as during sustained visuospatial attention. Using EEG, we investigated whether associating transient distractors with reward value would increase their distractibility and lead to greater decrements in concurrent sustained spatial attention directed elsewhere. Human participants learned to associate three differently colored, laterally presented squares with rewards of varying magnitude (zero, small, and large). These colored squares were then periodically reintroduced as distractors at the same lateral locations during a demanding sustained-attention rapid-serial-visual-presentation (RSVP) task at the midline. Behavioral and neural evidence indicated that participants had successfully learned and maintained the reward associations to the distractors. During the RSVP task, consistent with prior work, we found that the distractors generated dips in the instantaneous amplitude of the steady-state visual evoked potentials (SSVEPs) elicited by the midline RSVP stimuli, indicating that the distractors were indeed transiently disrupting sustained spatial attention. Contrary to our hypotheses, however, the magnitude of this dip did not differ by the magnitude of the distractor’s reward associations. These results indicate that while sustained spatial attention can be impaired by the introduction of distractors at another location, the main distraction process is resistant to the distractors’ reward associations, thus providing evidence of an important boundary condition to value-driven attentional capture.

Event-related synchronization/desynchronization and functional neuroanatomical regions associated with fatigue effects on cognitive flexibility

Cognitive flexibility is an essential prerequisite for goal-directed behavior, and daily observations already show that it deteriorates when one is engaged in a task for a (too) long time. Yet, the neural mechanisms underlying such fatigability effect in cognitive flexibility are poorly understood. We examined how theta, alpha, and beta frequency event-related synchronization and desynchronization processes during cued memory-based task switching are modulated by time-on-task effects. We put special emphasis on the examination of functional neuroanatomical regions being associated with these modulations, using EEG beamforming. We show clear declines in task switching performance (increased switch costs) with time on task. For processes occurring before rule switching or repetition processes, we show that anticipatory attentional sampling and selection mechanisms associated with fronto-parietal structures are modulated by time-on-task effects but sensory areas (occipital cortex) also show fatigability-dependent modulations. After target stimulus presentation, the allocation of processing resources for response selection as reflected by theta-related activity in parietal cortices is compromised with time on task and similarly a concomitant increase in alpha and beta band-related attentional processing or gating mechanisms in frontal and occipital regions. Yet, considering the behavioral data showing an apparent decline in performance, this probably compensatory increase is still insufficient to allow reasonable performance. The same is likely the case for processes occurring before rule switching or repetition processes. Comparative analyses show that modulations of alpha band activity are as strongly modulated by fatigability as theta band activity. Implications of these findings for theoretical concepts on fatigability are discussed.NEW & NOTEWORTHY We examine the neurophysiological and functional neuroanatomical basis of fatigability in cognitive flexibility. We show that alpha and theta modulations in fronto-parietal and primary sensory areas are central for the understanding of fatigability effects in cognitive flexibility.

On the Boundaries between Decision and Action: Effector-selective Lateralization of Beta-frequency Power Is Modulated by the Lexical Frequency of Printed Words

Current computational and neuroscientific models of decision-making posit a discrete, serial processing distinction between upstream decisional stages and downstream processes of motor-response implementation. We investigated this framework in the context of two-alternative forced-choice tasks on linguistic stimuli, words and pseudowords. In two experiments, we assessed the impact of lexical frequency and action semantics on two effector-selective EEG indexes of motor-response activation: the lateralized readiness potential and the lateralization of beta-frequency power. This allowed us to track potentially continuous streams of processing progressively mapping the evaluation of linguistic stimuli onto corresponding response channels. Whereas action semantics showed no influence on EEG indexes of motor-response activation, lexical frequency affected the lateralization of response-locked beta-frequency power. We argue that these observations point toward a continuity between linguistic processing of word input stimuli and implementation of corresponding choice in terms of motor behavior. This interpretation challenges the commonly held assumption of a discrete processing distinction between decisional and motor-response processes in the context of decisions based on symbolic stimuli.

The high-working load states induced by action real-time strategy gaming: An EEG power spectrum and network study

Action Real-time Strategy Gaming (ARSG) is a cognitively demanding task that requires attention, sensorimotor skills, high-level team coordination, and strategy-making abilities. Thus, ARSG can offer important, new insights into learning-related neural plasticity. However, little research has examined how the brain allocates cognitive resources in ARSG. By analyzing power spectrums and electroencephalograph (EEG) functional connectivity (FC) networks, this study compared multiple conditions (resting, movie watching, ARSG, and Life simulation gaming - LSG) in two experiments. Consistent with previous research, we found that brain waves appeared to be de-assimilated after activation. Furthermore, results showed that ARSG was associated with higher activation and workload as indicated by θ-waves, and required higher attention as reflected by β-waves. Furthermore, as participants began ARSG, the allocation of cognitive resource gradually prioritized the frontal area, which controls attention, decision-making, monitoring, and mnemonic processing, while participants also showed an enhanced ability to process information under the ARSG condition as indicated by network characteristics. These electrophysiological changes observed in ARSG were not found under LSG. Thus, this study applied both power spectrum and EEG FC networks analyses to ARSG research, revealing characteristics of brain waves in typical areas and how the brain gradually changes from low-working load states to high-working load states based on real-time EEG recordings.

The strength of alpha and gamma oscillations predicts behavioral switch costs

Cognitive flexibility is often examined using task-switch paradigms, whereby individuals either switch between tasks or repeat the same task on successive trials. The behavioral costs of switching in terms of accuracy and reaction time are well-known, but the oscillatory dynamics underlying such costs are poorly understood. Herein, we examined 25 healthy adults who performed a task-switching paradigm during magnetoencephalography (MEG). All MEG data were transformed into the time-frequency domain and significant oscillatory responses were imaged separately per condition (i.e., switch, repeat) using a beamformer. To determine the impact of task-switching on the neural dynamics, the resulting images were examined using paired-samples t-tests. Whole-brain correlations were also computed using the switch-related difference images (switch - repeat) and the switch-related behavioral data (i.e., switch costs). Our key results indicated stronger decreases in alpha and beta activity, and greater increases in gamma activity in nodes of the cingulo-opercular and fronto-parietal networks during switch relative to repeat trials. In addition, behavioral switch costs were positively correlated with switch-related differences in right frontal and inferior parietal alpha activity, and negatively correlated with switch effects in anterior cingulate and right temporoparietal gamma activity. In other words, participants who had a greater decrease in alpha or increase in gamma in these respective regions had smaller behavioral switch costs, which suggests that these oscillations are critical to supporting cognitive flexibility. In sum, we provide novel data linking switch effects and gamma oscillations, and employed a whole-brain approach to directly link switch-related oscillatory differences with switch-related performance differences.

Dynamic low frequency EEG phase synchronization patterns during proactive control of task switching

Cognitive flexibility is critical for humans living in complex societies with ever-growing multitasking demands. Yet the low-frequency neural dynamics of distinct task-specific and domain-general mechanisms sub-serving mental flexibility are still ill-defined. Here we estimated phase electroencephalogram synchronization by using inter-trial phase coherence (ITPC) at the source space while twenty six young participants were intermittently cued to switch or repeat their perceptual categorization rule of Gabor gratings varying in color and thickness (switch task). Therefore, the aim of this study was to examine whether a proactive control is associated with connectivity only in the frontoparietal theta network, or also involves distinct neural connectivity within the delta band, as distinct neural signatures while preparing to switch or repeat a task set, respectively. To this end, we focused the analysis on late-latencies (from 500 to 800 msec post-cue onset), since they are known to be associated with top-down cognitive control processes. We confirmed that proactive control during a task switch was associated with frontoparietal theta connectivity. But importantly, we also found a distinct role of delta band oscillatory synchronization in proactive control, engaging more posterior frontotemporal regions as opposed to frontoparietal theta connectivity. Additionally, we built a regression model by using the ITPC results in delta and theta bands as predictors, and the behavioral accuracy in the switch task as the criterion, obtaining significant results for both frequency bands. All these findings support the existence of distinct proactive cognitive control processes related to functionally distinct though highly complementary theta and delta frontoparietal and temporoparietal oscillatory networks at late-latency temporal scales.

Data-driven visualization of multichannel EEG coherence networks based on community structure analysis

An electroencephalography (EEG) coherence network is a representation of functional brain connectivity, and is constructed by calculating the coherence between pairs of electrode signals as a function of frequency. Typical visualizations of coherence networks use a matrix representation with rows and columns representing electrodes and cells representing coherences between electrode signals, or a 2D node-link diagram with vertices representing electrodes and edges representing coherences. However, such representations do not allow an easy embedding of spatial information or they suffer from visual clutter, especially for multichannel EEG coherence networks. In this paper, a new method for data-driven visualization of multichannel EEG coherence networks is proposed to avoid the drawbacks of conventional methods. This method partitions electrodes into dense groups of spatially connected regions. It not only preserves spatial relationships between regions, but also allows an analysis of the functional connectivity within and between brain regions, which could be used to explore the relationship between functional connectivity and underlying brain structures. As an example application, the method is applied to the analysis of multichannel EEG coherence networks obtained from older and younger adults who perform a cognitive task. The proposed method can serve as a preprocessing step before a more detailed analysis of EEG coherence networks.

Statistical non-parametric mapping in sensor space

Establishing the significance of observed effects is a preliminary requirement for any meaningful interpretation of clinical and experimental Electroencephalography or Magnetoencephalography (MEG) data. We propose a method to evaluate significance on the level of sensors whilst retaining full temporal or spectral resolution. Input data are multiple realizations of sensor data. In this context, multiple realizations may be the individual epochs obtained in an evoked-response experiment, or group study data, possibly averaged within subject and event type, or spontaneous events such as spikes of different types. In this contribution, we apply Statistical non-Parametric Mapping (SnPM) to MEG sensor data. SnPM is a non-parametric permutation or randomization test that is assumption-free regarding distributional properties of the underlying data. The method, referred to as Maps SnPM, is demonstrated using MEG data from an auditory mismatch negativity paradigm with one frequent and two rare stimuli and validated by comparison with Topographic Analysis of Variance (TANOVA). The result is a time- or frequency-resolved breakdown of sensors that show consistent activity within and/or differ significantly between event or spike types. TANOVA and Maps SnPM were applied to the individual epochs obtained in an evoked-response experiment. The TANOVA analysis established data plausibility and identified latencies-of-interest for further analysis. Maps SnPM, in addition to the above, identified sensors of significantly different activity between stimulus types.

Transient Distraction and Attentional Control during a Sustained Selective Attention Task

Distracting stimuli in the environment can pull our attention away from our goal-directed tasks. fMRI studies have implicated regions in right frontal cortex as being particularly important for processing distractors [e.g., de Fockert, J. W., & Theeuwes, J. Role of frontal cortex in attentional capture by singleton distractors. Brain and Cognition, 80, 367-373, 2012; Demeter, E., Hernandez-Garcia, L., Sarter, M., & Lustig, C. Challenges to attention: A continuous arterial spin labeling (ASL) study of the effects of distraction on sustained attention. Neuroimage, 54, 1518-1529, 2011]. Less is known, however, about the timing and sequence of how right frontal or other brain regions respond selectively to distractors and how distractors impinge upon the cascade of processes related to detecting and processing behaviorally relevant target stimuli. Here we used EEG and ERPs to investigate the neural consequences of a perceptually salient but task-irrelevant distractor on the detection of rare target stimuli embedded in a rapid, serial visual presentation (RSVP) stream. We found that distractors that occur during the presentation of a target interfere behaviorally with detection of those targets, reflected by reduced detection rates, and that these missed targets show a reduced amplitude of the long-latency, detection-related P3 component. We also found that distractors elicited a right-lateralized frontal negativity beginning at 100 msec, whose amplitude negatively correlated across participants with their distraction-related behavioral impairment. Finally, we also quantified the instantaneous amplitude of the steady-state visual evoked potentials elicited by the RSVP stream and found that the occurrence of a distractor resulted in a transient amplitude decrement of the steady-state visual evoked potential, presumably reflecting the pull of attention away from the RSVP stream when distracting stimuli occur in the environment.

Electrophysiological evidence for preparatory reconfiguration before voluntary task switches but not cued task switches

An unresolved issue in the task-switching literature is whether preparatory reconfiguration occurs before a change of task. In this study, we used event-related potentials (ERPs) to determine whether preparatory reconfiguration occurs during two different task-switching procedures: voluntary and cued task switching. We focused on two ERP components that index different cognitive operations. The contingent negative variation (CNV) is a sensitive measure of a participant's preparedness to use a specific stimulus-response mapping. In contrast, the P3 indexes memory updating. We found a pronounced modulation of the CNV before voluntary task switches, but not before cued task switches. Instead, cued task switches were preceded by a larger P3, as compared with task repetitions. Our findings suggest that task set reconfiguration is carried out prior to voluntary task switches, whereas memory processes dominate cued task switches.

The Influence of Pre-stimulus EEG Activity on Reaction Time During a Verbal Sternberg Task is Related to Musical Expertise

Previous work highlighted the possibility that musical training has an influence on cognitive functioning. The suggested reason for this influence is the strong recruitment of attention, planning, and working memory functions during playing a musical instrument. The purpose of the present work was twofold, namely to evaluate the general relationship between pre-stimulus electrophysiological activity and cognition, and more specifically the influence of musical expertise on working memory functions. With this purpose in mind, we used covariance mapping analyses to evaluate whether pre-stimulus electroencephalographic activity is predictive for reaction time during a visual working memory task (Sternberg paradigm) in musicians and non-musicians. In line with our hypothesis, we replicated previous findings pointing to a general predictive value of pre-stimulus activity for working memory performance. Most importantly, we also provide first evidence for an influence of musical expertise on working memory performance that could distinctively be predicted by pre-stimulus spectral power. Our results open novel perspectives for better comprehending the vast influences of musical expertise on cognition.

Neural basis of postural focus effect on concurrent postural and motor tasks: phase-locked electroencephalogram responses

Dual-task performance is strongly affected by the direction of attentional focus. This study investigated neural control of a postural-suprapostural procedure when postural focus strategy varied. Twelve adults concurrently conducted force-matching and maintained stabilometer stance with visual feedback on ankle movement (visual internal focus, VIF) and on stabilometer movement (visual external focus, VEF). Force-matching error, dynamics of ankle and stabilometer movements, and event-related potentials (ERPs) were registered. Postural control with VEF caused superior force-matching performance, more complex ankle movement, and stronger kinematic coupling between the ankle and stabilometer movements than postural control with VIF. The postural focus strategy also altered ERP temporal-spatial patterns. Postural control with VEF resulted in later N1 with less negativity around the bilateral fronto-central and contralateral sensorimotor areas, earlier P2 deflection with more positivity around the bilateral fronto-central and ipsilateral temporal areas, and late movement-related potential commencing in the left frontal-central area, as compared with postural control with VIF. The time-frequency distribution of the ERP principal component revealed phase-locked neural oscillations in the delta (1-4Hz), theta (4-7Hz), and beta (13-35Hz) rhythms. The delta and theta rhythms were more pronounced prior to the timing of P2 positive deflection, and beta rebound was greater after the completion of force-matching in VEF condition than VIF condition. This study is the first to reveal the neural correlation of postural focusing effect on a postural-suprapostural task. Postural control with VEF takes advantage of efficient task-switching to facilitate autonomous postural response, in agreement with the "constrained-action" hypothesis.

Temporal dynamics of sensorimotor integration in speech perception and production: independent component analysis of EEG data

Activity in anterior sensorimotor regions is found in speech production and some perception tasks. Yet, how sensorimotor integration supports these functions is unclear due to a lack of data examining the timing of activity from these regions. Beta (~20 Hz) and alpha (~10 Hz) spectral power within the EEG μ rhythm are considered indices of motor and somatosensory activity, respectively. In the current study, perception conditions required discrimination (same/different) of syllables pairs (/ba/ and /da/) in quiet and noisy conditions. Production conditions required covert and overt syllable productions and overt word production. Independent component analysis was performed on EEG data obtained during these conditions to (1) identify clusters of μ components common to all conditions and (2) examine real-time event-related spectral perturbations (ERSP) within alpha and beta bands. 17 and 15 out of 20 participants produced left and right μ-components, respectively, localized to precentral gyri. Discrimination conditions were characterized by significant (pFDR < 0.05) early alpha event-related synchronization (ERS) prior to and during stimulus presentation and later alpha event-related desynchronization (ERD) following stimulus offset. Beta ERD began early and gained strength across time. Differences were found between quiet and noisy discrimination conditions. Both overt syllable and word productions yielded similar alpha/beta ERD that began prior to production and was strongest during muscle activity. Findings during covert production were weaker than during overt production. One explanation for these findings is that μ-beta ERD indexes early predictive coding (e.g., internal modeling) and/or overt and covert attentional/motor processes. μ-alpha ERS may index inhibitory input to the premotor cortex from sensory regions prior to and during discrimination, while μ-alpha ERD may index sensory feedback during speech rehearsal and production.

Human EEG uncovers latent generalizable rule structure during learning

Human cognition is flexible and adaptive, affording the ability to detect and leverage complex structure inherent in the environment and generalize this structure to novel situations. Behavioral studies show that humans impute structure into simple learning problems, even when this tendency affords no behavioral advantage. Here we used electroencephalography to investigate the neural dynamics indicative of such incidental latent structure. Event-related potentials over lateral prefrontal cortex, typically observed for instructed task rules, were stratified according to individual participants' constructed rule sets. Moreover, this individualized latent rule structure could be independently decoded from multielectrode pattern classification. Both neural markers were predictive of participants' ability to subsequently generalize rule structure to new contexts. These EEG dynamics reveal that the human brain spontaneously constructs hierarchically structured representations during learning of simple task rules.

Lateralized power spectra of the EEG as an index of visuospatial attention

The electroencephalogram (EEG) was measured in an endogenous orienting paradigm where symbolic cues indicated the likely side of to-be-discriminated targets. Combined results of event-related lateralizations (ERLs) and a newly derived measure from wavelet analyses that we applied on the raw EEG and individual event-related potentials (ERPs), the lateralized power spectra (LPS) and the LPS-ERP, respectively, confirmed the common view that endogenous orienting operates by anterior processes, probably originating from the frontal eye fields, modulating processing in parietal and occipital areas. The LPS data indicated that modulation takes place by increased inhibition of the irrelevant visual field and/or disinhibition of the relevant to-be-attended visual field. Combined use of ERLs, the LPS, and the LPS-ERP indicated that most of the involved processes can be characterized as externally evoked, either or not with clear individual differences as some evoked effects were only visible in the LPS-ERERP, whereas few processes seemed to have an internally induced nature. Use of the LPS and the LPS-ERP may be advantageous as it enables to determine the involvement of internally generated lateralized processes that are not strictly bound to an event like stimulus onset.

Reconciling the influence of task-set switching and motor inhibition processes on stop signal after-effects

Executive response functions can be affected by preceding events, even if they are no longer associated with the current task at hand. For example, studies utilizing the stop signal task have reported slower response times to “GO” stimuli when the preceding trial involved the presentation of a “STOP” signal. However, the neural mechanisms that underlie this behavioral after-effect are unclear. To address this, behavioral and electroencephalography (EEG) measures were examined in 18 young adults (18–30 years) on “GO” trials following a previously “Successful Inhibition” trial (pSI), a previously “Failed Inhibition” trial (pFI), and a previous “GO” trial (pGO). Like previous research, slower response times were observed during both pSI and pFI trials (i.e., “GO” trials that were preceded by a successful and unsuccessful inhibition trial, respectively) compared to pGO trials (i.e., “GO” trials that were preceded by another “GO” trial). Interestingly, response time slowing was greater during pSI trials compared to pFI trials, suggesting executive control is influenced by both task set switching and persisting motor inhibition processes. Follow-up behavioral analyses indicated that these effects resulted from between-trial control adjustments rather than repetition priming effects. Analyses of inter-electrode coherence (IEC) and inter-trial coherence (ITC) indicated that both pSI and pFI trials showed greater phase synchrony during the inter-trial interval compared to pGO trials. Unlike the IEC findings, differential ITC was present within the beta and alpha frequency bands in line with the observed behavior (pSI > pFI > pGO), suggestive of more consistent phase synchrony involving motor inhibition processes during the ITI at a regional level. These findings suggest that between-trial control adjustments involved with task-set switching and motor inhibition processes influence subsequent performance, providing new insights into the dynamic nature of executive control.

Sustained and transient attentional processes modulate neural predictors of memory encoding in consecutive time periods

Memory formation is commonly thought to rely on brain activity following an event. Yet, recent research has shown that even brain activity previous to an event can predict later recollection (subsequent memory effect, SME). In order to investigate the attentional sources of the SME, event-related potentials (ERPs) elicited by task cues preceding target words were recorded in a switched task paradigm that was followed by a surprise recognition test. Stay trials, that is, those with the same task as the previous trial, were contrasted with switch trials, which included a task switch compared to the previous trial. The underlying assumption was that sustained attention would be dominant in stay trials and that transient attentional reconfiguration processes would be dominant in switch trials. To determine the SME, local and global statistics of scalp electric fields were used to identify differences between subsequently remembered and forgotten items. Results showed that the SME in stay trials occurred in a time window from 2 to 1 sec before target onset, whereas the SME in switch trials occurred subsequently, in a time window from 1 to 0 sec before target onset. Both SMEs showed a frontal negativity resembling the topography of previously reported effects, which suggests that sustained and transient attentional processes contribute to the prestimulus SME in consecutive time periods.

Dissociable neural correlates of intention and action preparation in voluntary task switching

This electroencephalographic (EEG) study investigated the impact of between-task competition on intentional control in voluntary task switching. Anticipatory preparation for an upcoming task switch is a hallmark of top-down intentional control. Meanwhile, asymmetries in performance and voluntary choice when switching between tasks differing in relative strength reveal the effects of between-task competition, reflected in a surprising bias against switching to an easier task. Here, we assessed the impact of this bias on EEG markers of intentional control during preparation for an upcoming task switch. The results revealed strong and varied effects of between-task competition on EEG markers of global task preparation—a frontal contingent negative variation (CNV), a posterior slow positive wave, and oscillatory activity in the alpha band (8–12 Hz) over posterior scalp sites. In contrast, we observed no between-task differences in motor-specific task preparation, as indexed by the lateralized readiness potential and by motor-related amplitude asymmetries in the mu (9–13 Hz) and beta (18–26 Hz) frequency bands. Collectively, these findings demonstrate that between-task competition directly influences the formation of top-down intentions, not only their expression in overt behavior. Specifically, this influence occurs at the level of global task intention rather than the preparation of specific actions.

Do resting brain dynamics predict oddball evoked-potential?

Background

The oddball paradigm is widely applied to the investigation of cognitive function in neuroscience and in neuropsychiatry. Whether cortical oscillation in the resting state can predict the elicited oddball event-related potential (ERP) is still not clear. This study explored the relationship between resting electroencephalography (EEG) and oddball ERPs. The regional powers of 18 electrodes across delta, theta, alpha and beta frequencies were correlated with the amplitude and latency of N1, P2, N2 and P3 components of oddball ERPs. A multivariate analysis based on partial least squares (PLS) was applied to further examine the spatial pattern revealed by multiple correlations.

Results

Higher synchronization in the resting state, especially at the alpha spectrum, is associated with higher neural responsiveness and faster neural propagation, as indicated by the higher amplitude change of N1/N2 and shorter latency of P2. None of the resting quantitative EEG indices predict P3 latency and amplitude. The PLS analysis confirms that the resting cortical dynamics which explains N1/N2 amplitude and P2 latency does not show regional specificity, indicating a global property of the brain.

Conclusions

This study differs from previous approaches by relating dynamics in the resting state to neural responsiveness in the activation state. Our analyses suggest that the neural characteristics carried by resting brain dynamics modulate the earlier/automatic stage of target detection.

Addiction, adolescence, and the integration of control and motivation

The likelihood of initiating addictive behaviors is higher during adolescence than during any other developmental period. The differential developmental trajectories of brain regions involved in motivation and control processes may lead to adolescents' increased risk taking in general, which may be exacerbated by the neural consequences of drug use. Neuroimaging studies suggest that increased risk-taking behavior in adolescence is related to an imbalance between prefrontal cortical regions, associated with executive functions, and subcortical brain regions related to affect and motivation. Dual-process models of addictive behaviors are similarly concerned with difficulties in controlling abnormally strong motivational processes. We acknowledge concerns raised about dual-process models, but argue that they can be addressed by carefully considering levels of description: motivational processes and top-down biasing can be understood as intertwined, co-developing components of more versus less reflective states of processing. We illustrate this with a model that further emphasizes temporal dynamics. Finally, behavioral interventions for addiction are discussed. Insights in the development of control and motivation may help to better understand - and more efficiently intervene in - vulnerabilities involving control and motivation.

Are voluntary switches corrected repetitions?

While recent years have witnessed a growing interest in Voluntary Task Switching (VTS), the control mechanisms that are required in order to switch tasks on a voluntary basis remain to be identified. Starting from the finding that in VTS the proportion of task repetitions is usually higher than the proportion of task switches (task-repetition bias), the present electrophysiological study tests and confirms the hypothesis that, during VTS, one initially re-selects the previously executed task, before correcting this bias and selecting the alternative task. On the one hand, these findings allow us to describe how people switch cognitive tasks voluntarily. On the other hand, our approach underlines the usefulness of electrophysiological measures in understanding the processes by which voluntary behavior occurs.

It's about Time

The purpose of this review/opinion paper is to argue that human cognitive neuroscience has focused too little attention on how the brain may use time and time-based coding schemes to represent, process, and transfer information within and across brain regions. Instead, the majority of cognitive neuroscience studies rest on the assumption of functional localization. Although the functional localization approach has brought us a long way toward a basic characterization of brain functional organization, there are methodological and theoretical limitations of this approach. Further advances in our understanding of neurocognitive function may come from examining how the brain performs computations and forms transient functional neural networks using the rich multi-dimensional information available in time. This approach rests on the assumption that information is coded precisely in time but distributed in space; therefore, measures of rapid neuroelectrophysiological dynamics may provide insights into brain function that cannot be revealed using localization-based approaches and assumptions. Space is not an irrelevant dimension for brain organization; rather, a more complete understanding of how brain dynamics lead to behavior dynamics must incorporate how the brain uses time-based coding and processing schemes.

Neural correlates of task and source switching: similar or different?

Controlling everyday behaviour relies on the ability to configure appropriate task sets and guide attention towards information relevant to the current context and goals. Here, we ask whether these two aspects of cognitive control have different neural bases. Electrical brain activity was recorded while sixteen adults performed two discrimination tasks. The tasks were performed on either a visual input (letter on the screen) or self-generated information (letter generated internally by continuing the alphabetical sequence). In different blocks, volunteers either switched between (i) the two tasks, (ii) the two sources of information, or (iii) tasks and source of information. Event-related potentials differed significantly between switch and no-switch trials from an early point in time, encompassing at least three distinct effects. Crucially, although these effects showed quantitative differences across switch types, no qualitative differences were observed. Thus, at least under the current circumstances, switching between different tasks and between perceptually derived or self-generated sources of information rely on similar neural correlates until at least 900 ms after the onset of a switch event.

Dynamic crossmodal links revealed by steady-state responses in auditory-visual divided attention

Frequency tagging has been often used to study intramodal attention but not intermodal attention. We used EEG and simultaneous frequency tagging of auditory and visual sources to study intermodal focused and divided attention in detection and discrimination performance. Divided-attention costs were smaller, but still significant, in detection than in discrimination. The auditory steady-state response (SSR) showed no effects of attention at frontocentral locations, but did so at occipital locations where it was evident only when attention was divided between audition and vision. Similarly, the visual SSR at occipital locations was substantially enhanced when attention was divided across modalities. Both effects were equally present in detection and discrimination. We suggest that both effects reflect a common cause: An attention-dependent influence of auditory information processing on early cortical stages of visual information processing, mediated by enhanced effective connectivity between the two modalities under conditions of divided attention.

Movement planning and reprogramming in individuals with autism

Two experiments explored how individuals with and without autism plan and reprogram movements. Participants were given partial or complete information regarding the location of the upcoming manual movement. In Experiment 1, direct information specified the hand or direction of the upcoming movement. These results replicated previous reports that participants with autism utilize advance information to prepare their movements in the same manner as their chronologically age matched peers. Experiment 2 examined how individuals respond to an unexpected change in the movement requirements. Participants received advance information about the hand and direction of the upcoming movement. On 20% of the trials participants needed to adjust either the hand or direction they had prepared. Overall, the individuals with autism had difficulty reprogramming already planned movements, particularly if a different effector was required.

Adaptive control of response preparedness in task switching

When rapidly switching between two tasks, bivalent stimuli can accidentally trigger the previously executed and therefore still activated response. Recently, it has been suggested that behavioral response-repetition effects reflect response inhibition that reduces the risk of such erroneous response repetitions. The present study investigated neural correlates of this inhibition process using lateralized readiness potentials (LRP). In three experiments, we demonstrate a response-switch bias emerging during the preparatory interval which is independent of task sequence (Experiment 1), which is linked to task preparation (Experiment 2), and which is present only under task-switching conditions (Experiment 3). These results suggest that the bias reflects a control process that adaptively regulates response preparedness.

When the brain changes its mind: flexibility of action selection in instructed and free choices

The neural mechanisms underlying the selection and initiation of voluntary actions in the absence of external instructions are poorly understood. These mechanisms are usually investigated using a paradigm where different movement choices are self-generated by a participant on each trial. These "free choices" are compared with "instructed choices," in which a stimulus informs subjects which action to make on each trial. Here, we introduce a novel paradigm to investigate these modes of action selection, by measuring brain processes evoked by an instruction to either reverse or maintain free and instructed choices in the period before a "go" signal. An unpredictable instruction to change a response plan had different effects on free and instructed choices. In instructed trials, change cues evoked a larger P300 than no-change cues, leading to a significant interaction of choice and change condition. Free-choice trials displayed a trend toward the opposite pattern. These results suggest a difference between updating of free and instructed action choices. We propose a theoretical framework for internally generated action in which representations of alternative actions remain available until a late stage in motor preparation. This framework emphasizes the high modifiability of voluntary action.

Neural predictors of moment-to-moment fluctuations in cognitive flexibility

Cognitive flexibility is a crucial human ability allowing efficient adaptation to changing task challenges. Although a person's degree of flexibility can vary from moment to moment, the conditions regulating such fluctuations are not well understood. Using a task-switching procedure with fMRI, we found several brain regions in which neural activity preceding each trial predicted subsequent cognitive flexibility. Specifically, as pretrial activity increased, performance improved on trials when the task switched but did not improve when the task repeated. Regions from which flexibility could be predicted reliably included the basal ganglia, anterior cingulate cortex, prefrontal cortex, and posterior parietal cortex. Although further analysis revealed similarities across the regions in how flexibility was predicted, results supported the existence of multiple independent sources of prediction. These results reveal distinct neural mechanisms underlying fluctuations in cognitive flexibility.

Neurophysiological signature of effective anticipatory task-set control: a task-switching investigation

Changing between cognitive tasks requires a reorganization of cognitive processes. Behavioural evidence suggests this can occur in advance of the stimulus. However, the existence or detectability of an anticipatory task-set reconfiguration process remains controversial, in part because several neuroimaging studies have not detected extra brain activity during preparation for a task switch relative to a task repeat. In contrast, electrophysiological studies have identified potential correlates of preparation for a task switch, but their interpretation is hindered by the scarcity of evidence on their relationship to performance. We aimed to: (i) identify the brain potential(s) reflecting effective preparation for a task-switch in a task-cuing paradigm that shows clear behavioural evidence for advance preparation, and (ii) characterize this activity by means of temporal segmentation and source analysis. Our results show that when advance preparation was effective (as indicated by fast responses), a protracted switch-related component, manifesting itself as widespread posterior positivity and concurrent right anterior negativity, preceded stimulus onset for approximately 300 ms, with sources primarily in the left lateral frontal, right inferior frontal and temporal cortices. When advance preparation was ineffective (as implied by slow responses), or made impossible by a short cue-stimulus interval (CSI), a similar component, with lateral prefrontal generators, peaked approximately 300 ms poststimulus. The protracted prestimulus component (which we show to be distinct from P3 or contingent negative variation, CNV) also correlated over subjects with a behavioural measure of preparation. Furthermore, its differential lateralization for word and picture cues was consistent with a role for verbal self-instruction in preparatory task-set reconfiguration.

Data-driven visualization and group analysis of multichannel EEG coherence with functional units

A typical data-driven visualization of electroencephalography (EEG) coherence is a graph layout, with vertices representing electrodes and edges representing significant coherences between electrode signals. A drawback of this layout is its visual clutter for multichannel EEG. To reduce clutter, we define a functional unit (FU) as a data-driven region of interest (ROI). An FU is a spatially connected set of electrodes recording pairwise significantly coherent signals, represented in the coherence graph by a spatially connected clique. Earlier we presented two methods to detect FUs: a maximal clique based (MCB) method (time complexity O(3n/3), with n being the number of vertices) and a more efficient watershed based (WB) method (time complexity O (n2 log n)). To reduce the potential over-segmentation of the WB method, we introduce here an improved WB (IWB) method (time complexity O(n2 log n)). The IWB method merges basins representing FUs during the segmentation if they are spatially connected and if their union is a clique. The WB and IWB methods are both up to a factor of 100,000 faster than the MCB method for a typical multichannel setting with 128 EEG channels, thus making interactive visualization of multichannel EEG coherence possible. Results show that considering the MCB method as the gold standard, the difference between IWB and MCB FU maps is smaller than between WB and MCB FU maps. We also introduce two novel group maps for data-driven group analysis as extensions of the IWB method. First, the group mean coherence map preserves dominant features from a collection of individual FU maps. Second, the group FU size map visualizes the average FU size per electrode across a collection of individual FU maps. Finally, we employ an extensive case study to evaluate the IWB FU map and the two new group maps for data-driven group analysis. Results, in accordance with the conventional findings, indicate differences in EEG coherence between younger and older adults. However, they also suggest that an initial selection of hypothesis-driven ROIs could be extended with additional data-driven ROIs.

Dissociations between motor-related EEG measures in a cued movement sequence task

Different aspects of preparation, especially processes related to knowing what to prepare versus applying that foreknowledge effectively, may be reflected in different types of brain activity, e.g., the lateralized readiness potential (LRP), beta-band event-related desynchronization and phase locking. In a previous study in which subjects had to switch between response hands, dissociations were found between types of preparatory hand-related lateralization in evoked potentials, amplitude and phase locking (Gladwin et al., 2006) knowing what task set to switch to and effectively preparing that task set affected the different measures of lateralization. Similarly to how, in task switching, stimuli and responses must be correctly related to each other, in the preparation of movement sequences relations must be specified concerning motor processes. Similar dissociations as found in the task switching data might then be found in a cued movement sequence task. This possibility was explored by precueing elements of a two-movement sequence involving the left and right index fingers, and comparing various measures of electroencephalogram activity. Cues could specify the full sequence, either the first or the second element, or neither element. Knowing the first element was sufficient to lateralize the pattern of phase locking, but effects were found in the LRP and lateralized amplitude only when the full sequence was known. It seems likely that subjects only fully prepared the first response when they had full knowledge of the sequence so that the dissociation may be closely related to that found for task switching. Thus, the present data would appear to agree with previous results that couple response-foreknowledge with phase locking and the transformation of that foreknowledge into effective changes in component processes with evoked potential shifts. The results further underscore the general importance of considering different types of brain activity: depolarization, desynchronization and phase locking all appear to be involved in different aspects of cognitive control.

Movement-related EEG indices of preparation in task switching and motor control

Lateralized readiness potential (LRP) and time-frequency domain LRP-type measures, called motor-related amplitude asymmetries (MRAA), in the mu band (9-13 Hz; mu-MRAA) and the beta band (18-26 Hz; beta-MRAA) were used to study the time course of preparation in a task-switching task and a response precuing task. Several dissociations between LRP and mu-MRAA and beta-MRAA were found. Mu-MRAA and beta-MRAA, but not LRP, exhibited an early and strong reversal in cortical lateralization when advance preparation for a switch of response hand was required. LRP, but not mu-MRAA or beta-MRAA, was sensitive to manipulation of the probability that advance preparation of response hand would be useful in a response precuing task. These dissociations replicate earlier findings and suggest that movement-related cortical rhythms and cortical potentials are associated with distinct preparatory component processes that differ in terms of level of abstraction and effort, in line with similar functional distinctions between component processes underlying executive control in task switching. This suggests that a fine-grained analysis of subprocesses involved in motor control may provide important guiding principles for the study and understanding of levels and mechanisms of cognitive control.