Central and parietal event-related lateralizations in a flanker task

Affective associations towards running: fuzzy patterns of implicit-explicit interaction in young female runners and non-runners

Empirical evidence demonstrates that high concordance and low discrepancy of implicit and explicit affective processes facilitate consistent exercise behavior. Novice runners often have difficulties implementing their running behavior on a regular basis resulting in irregular running behavior. To investigate the potential value of affective associations 89 young female runners (regular and irregular) and non-runners were recruited. Affective associations towards running were measured through a Single-Target Implicit Association Test on the implicit level and by self-report on the explicit level. Implicit-explicit interaction (IEI) scores (i.e., implicit-explicit concordance and discrepancy) were derived from principal component analysis. Fuzzy k-means cluster analysis was used to identify patterns of interacting implicit-explicit affective associations. The resulting clusters were assessed for differences in previous running experience, current running behavior, motivational and intentional aspects. Four meaningful overlapping clusters were found and labeled according to their prevalent IEI patterns (i.e., "positive non-discrepant", "positive discrepant", "negative discrepant", "negative non-discrepant"). Significant differences between clusters were found for past running experience, current running behavior, motivational and intentional aspects. The results indicate that running behavior varies between and within patterns of affective associations. In line with previous findings, positive non-discrepant implicit and explicit affective associations are linked to more consistent running behavior, while negative non-discrepant affect is associated with non-runners. However, the occurrence of discrepant implicit-explicit affective associations in young women differing in running behavior, motivation, and intention broadens the view of the complex relationship between affective processes and exercise behavior. In conclusion, individualized interventions that take into account the implicit-explicit interaction of affective associations besides well-known cognitive self-regulatory resources may prove more effective for individuals who struggle to run regularly.

Keeping the pace: The effect of slow-paced breathing on error monitoring

Detecting errors is crucial for adapting one's own actions. Moreover, behavior is often optimized by adapting to maladaptive actions, i.e. errors. In this regard, recent studies and models of error monitoring point to an involvement of emotional states in error monitoring. A psychophysiological correlate of the latter is the error negativity or error-related negativity (N_e/ERN), reflecting partly the functional implementation of anterior cingulate cortex functions. In the present study, we aimed to test whether neurophysiological aspects of error monitoring can be altered by a relaxation technique, i.e. slow-paced breathing. Slow-paced breathing has been shown to increase cardiac vagal activity. According to the neurovisceral integration model, cardiac vagal activity is thought to be a marker of the effectiveness of executive functions. We tested the effect of slow-paced breathing on error monitoring, i.e. the N_e/ERN and behavioral adaptation in a modified flanker task, a cognitive task during which performance depends on executive control. The N_e was increased following slow-paced breathing compared to a passive control condition. Furthermore, behavioral results indicate that response variability decreased in the slow-paced breathing condition whereas overall performance remained constant. We conclude that slow-paced breathing improves the ability to focus on the task at hand. Thus, the error monitoring system is being supported in keeping the pace, i.e. tracking responses.

Do alerting signals increase the size of the attentional focus?

Previous research has shown that the presentation of an auditory alerting signal before a visual target increases the interference from flanking distractors. Recently, it has been suggested that this increase in interference may be due to an expansion of the spatial focus of attention. In five experiments, this hypothesis was tested by using a probe technique dedicated to measuring variations in the size of the attentional focus: In the majority of trials, participants performed a letter discrimination task in which their attention was focused on a central target letter. In a randomly intermixed probe task, the size of the attentional focus was measured by letting participants respond to a probe occurring at varying positions. In all experiments, reaction time (RT) to the probe increased from the most central to more lateral probe positions. This V-shaped probe-RT function, however, was not flattened by the presentation of an alerting signal. Overall, this pattern of results is inconsistent with the hypothesis that alerting signals increase the attentional focus. Instead, it is consistent with nonspatial accounts that attribute the increase in interference to an alerting effect on perceptual processing, which then leads to a detrimental effect at the level of response selection.

Difficult action decisions reduce the sense of agency: A study using the Eriksen flanker task

The sense of agency refers to the feeling that we are in control of our actions and, through them, of events in the outside world. Much research has focused on the importance of retrospectively matching predicted and actual action outcomes for a strong sense of agency. Yet, recent studies have revealed that a metacognitive signal about the fluency of action selection can prospectively inform our sense of agency. Fluent, or easy, action selection leads to a stronger sense of agency over action outcomes than dysfluent, or difficult, selection. Since these studies used subliminal priming to manipulate action selection, it remained unclear whether supraliminal stimuli affecting action selection would have similar effects. We used supraliminal flankers to manipulate action selection in response to a central target. Experiment 1 revealed that conflict in action selection, induced by incongruent flankers and targets, led to reduced agency ratings over an outcome that followed the participant's response, relative to neutral and congruent flanking conditions. Experiment 2 replicated this result, and extended it to free choice between alternative actions. Finally, Experiment 3 varied the stimulus onset asynchrony (SOA) between flankers and target. Action selection performance varied with SOA. Agency ratings were always lower in incongruent than congruent trials, and this effect did not vary across SOAs. Sense of agency is influenced by a signal that tracks conflict in action selection, regardless of the visibility of stimuli inducing conflict, and even when the timing of the stimuli means that the conflict may not affect performance.

Classifying Response Correctness across Different Task Sets: A Machine Learning Approach

Erroneous behavior usually elicits a distinct pattern in neural waveforms. In particular, inspection of the concurrent recorded electroencephalograms (EEG) typically reveals a negative potential at fronto-central electrodes shortly following a response error (Ne or ERN) as well as an error-awareness-related positivity (Pe). Seemingly, the brain signal contains information about the occurrence of an error. Assuming a general error evaluation system, the question arises whether this information can be utilized in order to classify behavioral performance within or even across different cognitive tasks. In the present study, a machine learning approach was employed to investigate the outlined issue. Ne as well as Pe were extracted from the single-trial EEG signals of participants conducting a flanker and a mental rotation task and subjected to a machine learning classification scheme (via a support vector machine, SVM). Overall, individual performance in the flanker task was classified more accurately, with accuracy rates of above 85%. Most importantly, it was even feasible to classify responses across both tasks. In particular, an SVM trained on the flanker task could identify erroneous behavior with almost 70% accuracy in the EEG data recorded during the rotation task, and vice versa. Summed up, we replicate that the response-related EEG signal can be used to identify erroneous behavior within a particular task. Going beyond this, it was possible to classify response types across functionally different tasks. Therefore, the outlined methodological approach appears promising with respect to future applications.

Brief Report: Some Remarks About the Response Relatedness of the Error Negativity

The error negativity (Ne) is a prominent response-related potential reflecting error processing or response monitoring processes. Despite the huge amount of literature dealing with the Ne, only few studies investigated how close the Ne is related to the kind of response collected by the experimental setup. The present study investigated whether the Ne differs between force locked and force level related (aka button press) data. Indeed, the Ne was more pronounced for force onset compared to level trigger and appeared to be related to the steepness of the raise of force. These results implicate that the parameterization of the Ne has to be treated with caution under certain circumstances and it appears to be advisable to use force onset or the electromyogram to detect response onset if timing or latency is relevant.

Temporal dynamics of interference in Simon and Eriksen tasks considered within the context of a dual-process model

Behavioral and brain potential measures were employed to compare interference in Eriksen and Simon tasks. Assuming a dual-process model of interference elicited in speeded response tasks, we hypothesized that only lateralized stimuli in the Simon task induce fast S-R priming via direct unconditional processes, while Eriksen interference effects are induced later via indirect conditional processes. Delays to responses for incongruent trials were indeed larger in the Eriksen than in the Simon task. Only lateralized stimuli in the Simon task elicited early S-R priming, maximal at parietal areas. Incongruent flankers in the Eriksen task elicited interference later, visible as a lateralized N2. Eriksen interference also elicited an additional component (N350), which accounted for the larger behavioral interference effects in the Eriksen task. The findings suggest that interference and its resolution involve different processes for Simon and Eriksen tasks.

Aging and error processing: age related increase in the variability of the error-negativity is not accompanied by increase in response variability

Background

Several studies report an amplitude reduction of the error negativity (Ne or ERN), an event-related potential occurring after erroneous responses, in older participants. In earlier studies it was shown that the Ne can be explained by a single independent component. In the present study we aimed to investigate whether the Ne reduction usually found in older subjects is due to an altered component structure, i.e., a true alteration in response monitoring in older subjects.

Methodology/Principal Findings

Two age groups conducted two tasks with different stimulus response mappings and task difficulty. Both groups received fully balanced speed or accuracy instructions and an individually adapted deadline in both tasks. Event-related potentials, Independent Component analysis of EEG-data and between trial variability of the Ne were combined with analysis of error rates, coefficients of variation of RT-data and ex-Gaussian fittings to reaction times. The Ne was examined by means of ICA and PCA, yielding a prominent independent component on error trials, the Ne-IC. The Ne-IC was smaller in the older than the younger subjects for both speed and accuracy instructions. Also, the Ne-IC contributed to a much lesser extent to the Ne in older than in younger subjects. RT distribution parameters were not related to Ne/ERP-variability.

Conclusions/Significance

The results show a genuine reduction as well as a different component structure of the Ne in older compared to young subjects. This reduction is not reflected in behaviour, apart from a general slowing of older participants. Also, the Ne decline in the elderly is not due to speed accuracy trade-off. Hence, the results indicate that older subjects can compensate the reduction in control reflected in the reduced Ne, at least in simple tasks that induce reaction slips.

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.

Independent component analysis of erroneous and correct responses suggests online response control

After errors in reaction tasks, a sharp negative wave emerges in the event-related potential (ERP), the error (related) negativity (Ne or ERN). However, also after correct trials, an Ne-like wave is seen, called CRN or Nc, which is much smaller than the Ne. This study tested the hypothesis whether Ne and Nc reflect the same functional process, and whether this process is linked to online response control. For this purpose, independent component analysis (ICA) was utilized with the EEG data of two types of reaction tasks: a flanker task and a mental rotation task. To control for speed-accuracy effects, speed and accuracy instructions were balanced in a between subjects design. For both tasks ICA and dipole analysis revealed one component (Ne-IC) explaining most of the variance for the difference between correct and erroneous trials. The Ne-IC showed virtually the same features as the raw postresponse ERP, being larger for erroneous compared to correct trials and for the flanker than for the rotation task. In addition, it peaked earlier for corrected than for uncorrected errors. The results favor the hypothesis that Ne and Nc reflect the same process, which is modulated by response correctness and type of task. On the basis of the literature and the present results, we assume that this process induces online response control, which is much stronger in error than correct trials and with direct rather than indirect stimulus response mapping.

Cognitive versus automatic mechanisms of mood induction differentially activate left and right amygdala

The amygdala plays a key role in emotional processing. The specific contribution of the amygdala during the experience of one's own emotion, however, remains controversial and requires clarification. There is a long-standing debate on hemispheric lateralization of emotional processes, yet few studies to date directly investigated differential activation patterns for the left and right amygdala. Limited evidence supports right amygdala involvement in automatic processes of emotion and left amygdala involvement in conscious and cognitively controlled emotion processing. The present study investigated differential contributions of the left and right amygdala to cognitive and automatic mechanisms of mood induction. Using functional magnetic resonance imaging (fMRI), we examined hemispheric amygdala responses during two mood induction paradigms: a purely visual method presenting face stimuli and an audiovisual method using faces and music. Amygdala responses in 30 subjects (16 females) showed differences in lateralization patterns depending on the processing mode. The left amygdala exhibited comparable activation levels for both methods. The right amygdala, in contrast, showed increased activity only for the audiovisual condition and this activity was increasing over time. The left amygdala showed augmented activity with higher intensity ratings of negative emotional valence. These results support a left-lateralized cognitive and intentional control of mood and a right-sided more automatic induction of emotion that relies less on explicit reflection processes. The modulation of the left amygdala responses by subjective experience may reflect individual differences in the cognitive effort used to induce the mood. Thus, the central role of the amygdala may not be restricted to the perception of emotion in others but also extend into processes involved in regulation of mood.

Neurobehavioral effects during exposures to propionic acid--an indicator of chemosensory distraction?

The chemosensory effects of propionic acid (PA) in humans have not been conclusively studied and there is no established occupational exposure limit (OEL) in Germany. In addition to sensory irritation caused by PA, it was hypothesized that the annoying odor of PA might interfere with the performance results. There were 23 consenting healthy participants (12 female, 11 male) in the group studied. They were exposed for 4 h to PA in concentrations of 0.3, 5 and 10 ppm in a cross-over design. During these exposures, performance was recorded with four cognitive tests measuring response-inhibition, working memory, set-shifting, and divided attention. Odor annoyance, other chemosensory sensations, and acute symptoms were assessed before, during, and after exposure with standardized rating scales. Moderate odor annoyance and weak sensory irritation were reported during 5 and 10 ppm exposure conditions. The different levels of exposure to PA had no impact upon the results of three out of the four behavioral tests. The difficulties of the task were reflected in the results. However in the fourth, which was the response-inhibition task, there was significant increase in the error rates which corresponded to the exposure levels. Results from previous experiments suggested high odor annoyance at the investigated concentrations. Our findings showed that odor annoyance and reported sensory irritations were low. In conclusion, the hypothesis of a distractive effect due to the malodor of PA could not be confirmed. Only in concentrations as high as 10 ppm acute PA exposure affected the response accuracy of one of the four neurobehavioral task. For other more annoying substances, a neurobehavioral effect influenced by an indirect mechanism of resources competition is still conceivable.

Evidence for fast, low-level motor resonance to action observation: an MEG study

Lateralized magnetic fields were recorded from 12 subjects using a 151 channel magnetoencephalography (MEG) system to investigate temporal and functional properties of motor activation to the observation of goal-directed hand movements by a virtual actor. Observation of left and right hand movements generated a neuromagnetic lateralized readiness field (LRF) over contralateral motor cortex. The early onset of the LRF and the fact that the evoked component was insensitive to the correctness of the observed action suggest the operation of a fast and automatic form of motor resonance that may precede higher levels of action understanding.

Response monitoring in de novo patients with Parkinson's disease

Background

Parkinson's disease (PD) is accompanied by dysfunctions in a variety of cognitive processes. One of these is error processing, which depends upon phasic decreases of medial prefrontal dopaminergic activity. Until now, there is no study evaluating these processes in newly diagnosed, untreated patients with PD (“de novo PD”).

Methodology/Principal Findings

Here we report large changes in performance monitoring processes using event-related potentials (ERPs) in de novo PD-patients. The results suggest that increases in medial frontal dopaminergic activity after an error (Ne) are decreased, relative to age-matched controls. In contrast, neurophysiological processes reflecting general motor response monitoring (Nc) are enhanced in de novo patients.

Conclusions/Significance

It may be hypothesized that the Nc-increase is at costs of dopaminergic activity after an error; on a functional level errors may not always be detected and correct responses sometimes be misinterpreted as errors. This pattern differs from studies examining patients with a longer history of PD and may reflect compensatory processes, frequently occurring in pre-manifest stages of PD. From a clinical point of view the clearly attenuated Ne in the de novo PD patients may prove a useful additional tool for the early diagnosis of basal ganglia dysfunction in PD.

Neuroimaging of response interference in twins concordant or discordant for inattention and hyperactivity symptoms

Attention deficit hyperactivity disorder (ADHD) is to a large extent influenced by genetic factors, but environmental influences are considered important as well. To distinguish between functional brain changes underlying primarily genetically and environmentally mediated ADHD, we used functional magnetic resonance imaging (fMRI) to compare response interference in monozygotic twins highly concordant or discordant for attention problems (AP). AP scores were assessed longitudinally with the Child Behavior Check List attention problem scale (CBCL-AP). Response interference was measured during two executive function paradigms; a color-word Stroop and a flanker task. The neuroimaging results indicated that, across the entire sample, children with high CBCL-AP scores, relative to children with low CBCL-AP scores, showed decreased activation to response interference in dorsolateral prefrontal, parietal and temporal brain regions. Increased activation was noted in the premotor cortex and regions associated with visual selective attention processing, possibly reflecting compensatory mechanisms to maintain task performance. Specific comparisons of high and low scoring concordant twin pairs suggest that AP of genetic origin was characterized by decreased activation of the left dorsolateral prefrontal cortex during the Stroop task and right parietal lobe during the flanker task. In contrast, comparison of twins from discordant monozygotic pairs, suggests that AP of environmental origin was characterized by decreased activation in left and right temporal lobe areas, but only during Stroop interference. The finding of distinct brain activation changes to response interference in inattention/hyperactivity of "genetic" versus "environmental" origin, indicates that genetic and environmental risk factors for attention/hyperactivity problems affect the brain in different ways.

The effect of Parkinson's disease on interference control during action selection

Basal ganglia structures comprise a portion of the neural circuitry that is hypothesized to coordinate the selection and suppression of competing responses. Parkinson's disease (PD) may produce a dysfunction in these structures that alters this capacity, making it difficult for patients with PD to suppress interference arising from the automatic activation of salient or overlearned responses. Empirical observations thus far have confirmed this assumption in some studies, but not in others, due presumably to considerable inter-individual variability among PD patients. In an attempt to help resolve this controversy, we measured the performance of 50 PD patients and 25 healthy controls on an arrow version of the Eriksen flanker task in which participants were required to select a response based on the direction of a target arrow that was flanked by arrows pointing in the same (congruent) or opposite (incongruent) direction. Consistent with previous findings, reaction time (RT) increased with incongruent flankers compared to congruent or neutral flankers, and this cost of incongruence was greater among PD patients. Two novel findings are reported. First, distributional analyses, guided by dual-process models of conflict effects and the activation-suppression hypothesis, revealed that PD patients are less efficient at suppressing the activation of conflicting responses, even when matched to healthy controls on RT in a neutral condition. Second, this reduced efficiency was apparent in half of the PD patients, whereas the remaining patients were as efficient as healthy controls. These findings suggest that although poor suppression of conflicting responses is an important feature of PD, it is not evident in all medicated patients.

Age-related changes in cognitive conflict processing: An event-related potential study

Cognitive tasks involving conflicting stimuli and responses are associated with an early age-related decline in performance. Conflict and conflict-induced interference can be stimulus- or response-related. In classical stimulus-response compatibility tasks, such as the Stroop task, the event-related potential (ERP) usually reveals a greater negativity on incongruent versus congruent trials which has often been linked with conflict processing. However, it is unclear whether this negativity is related to stimulus- or response-related conflict, thus rendering the meaning of age-related changes inconclusive. In the present study, a modified Stroop task was used to focus on stimulus-related interference processes while excluding response-related interference. Since we intended to study work-relevant effects ERPs and performance were determined in young (about 30 years old) and middle-aged (about 50 years old) healthy subjects (total n=80). In the ERP, a broad negativity developed after incongruent versus congruent stimuli between 350 and 650 ms. An age-related increase of the latency and amplitude of this negativity was observed. These results indicate age-related alterations in the processing of conflicting stimuli already in middle age.

Does the error negativity reflect response conflict strength? Evidence from a Simon task

The error (-related) negativity (Ne or ERN) has been related to detecting the mismatch between incorrectly executed and appropriate responses or, alternatively, to the degree of conflict between different response alternatives. In this study different levels of response conflict were generated by manipulating task difficulty in a Simon task. According to the product of incorrect and subsequent correct EMG activation, the amount of conflict in error trials was indeed larger for the easy than for the hard condition. In contrast, Ne/ERN amplitudes did not differ between difficulty conditions, nor was the amount of conflict mirrored by Ne/ERN amplitude. Therefore, the present data are at variance with the hypothesis that the Ne/ERN reflects the degree of response conflict.

Effects of stimulus-response compatibility in Parkinson’s disease: a psychophysiological analysis

The present study investigated the mechanisms underlying stimulus-response compatibility effects in Parkinson's disease patients and matched controls. Since basal ganglia are involved in the selection and inhibition of competing responses we examined whether basal ganglia dysfunction in Parkinson's disease leads to greater interference effects compared to the control subjects. Reaction times and lateralized movement-related cortical potentials (lateralized readiness potential: LRP) were recorded in two modified Eriksen flanker tasks. Both groups were influenced by compatibility conditions; interference was seen as enhanced reaction time and error rate, as well as incorrect early LRP and delayed late LRP in incongruent trials. Altogether, behavioral and electrophysiological measures showed the interference to be rather smaller for the patients than for the controls. In contrast, facilitation did not differ among groups. Hence the claim that Parkinson's disease patients are more influenced than controls by interfering directional stimuli appears not always valid.