A carry-over task rule in task switching: An ERP investigation using a Go/Nogo paradigm

Investigations of executive control using a task-switching paradigm have consistently found longer reaction times for task-switch trials than task-repetition trials. This switch cost may result from interference by a stimulus-response (SR) rule carried over from the preceding alternative task. We examined event-related brain potential (ERP) evidence for such carry-over effects using a combined paradigm of task switching with Go/Nogo; Nogo trials, which require no response execution, should expose carry-over effects from preceding trials. On Go trials, twelve participants performed a button-pressing task in compatible (hand and signal direction consistent) and incompatible conditions, which switched predictably every three trials. Reaction times were longer on switch than on repetition trials. On compatible switch trials, a stimulus-locked lateralized readiness potential (sLRP) for Nogo stimuli revealed a positive dip, suggesting incorrect response activation in the early automatic process that was induced by a SR rule carried over from the preceding task.     

Interplay of neuronal processes during response inhibition: Results from a combined event-related potentials (ERPs)/transcranial magnetic stimulation (TMS) study on methylphenidate

The neuronal processes underlying response inhibition are often studied using either event-related potentials (ERPs) or by applying transcranial magnetic stimulation (TMS) to investigate excitatory and inhibitory processes in the motor system. We performed a more refined analysis of response inhibition by combining both approaches with the aim of identifying an interplay between ERPs and TMS parameters.During a go/nogo task, motor system excitability was measured using TMS single and double pulses and brain electrical activity was recorded in healthy adults (n = 14). Each participant completed two testing sessions, once on placebo and once on methylphenidate (double-blind, crossover design). Studying the effects of methylphenidate served as an example application for this combined approach.Developing regression models, inhibition-related TMS measures (e.g., short intracortical inhibition) and the contingent negative variation explained about 85% of the variance of the nogo-P3 under both MPH and placebo medication. The smaller the inhibitory effect in the motor system, the more terminal response control was required and the more resources were allocated for the evaluation of the inhibitory process, respectively, as indicated by a larger P3.Thus, an interplay between processes in the motor system (cortex) and control processes with sources in the prefrontal cortex and the anterior cingulate cortex (ACC) may take place, acting complementarily to facilitate a correct nogo-response.While ERPs rather represent initiation and monitoring of inhibitory processes and response control, motor inhibition may be best analyzed using TMS. A combined ERP/TMS analysis may allow for the development of distinct models concerning the interplay of processes involved in response inhibition.     

Cognitive control after distraction: event-related brain potentials (ERPs) dissociate between different processes of attentional allocation

Attentional reallocation after a distracting event is an important function of cognitive control. This process is tapped by the reorienting negativity (RON) event-related brain potential. It was argued that the RON reflects orientation of attention to relevant information in working memory. To test this hypothesis participants performed an auditory duration discrimination task. The stimuli were presented in a frequent standard or a rare deviant pitch with deviants resulting in behavioral distraction. Participants accomplished this task under two conditions: In the refocus condition participants were asked to respond to every stimulus; in the reorient condition participants were instructed to ignore deviant stimuli and omit a reaction. The results suggest that different functions of attentional allocation are reflected by two RON subcomponents: the fast orientation of the focus of attention in working memory and a subsequent poststimulus evaluation process.     

Response activation impairments in schizophrenia: evidence from the lateralized readiness potential

Previous research has demonstrated deficits in preresponse motor activity in schizophrenia, as evidenced by a reduced lateralized readiness potential (LRP). The LRP deficit could be due to increased activation of the incorrect response (e.g., failure to suppress competition) or to reduced activation of the correct response (e.g., a low-level impairment in response preparation). To distinguish these possibilities, we asked whether the LRP impairment is increased under conditions of strong response competition. We manipulated the compatibility of stimulus-response mappings (Experiment 1) and the compatibility of the target with flankers (Experiment 2). In both experiments, the patient LRP was reduced as much under conditions of low response competition as under high competition. These results are incompatible with a failure of patients to suppress competition and are instead consistent with a deficit in activating the correct response.     

Impaired response selection in schizophrenia: Evidence from the P3 wave and the lateralized readiness potential

Reaction times (RTs) are substantially prolonged in schizophrenia patients, but the latency of the P3 component is not. This suggests that the RT slowing arises from impairments in a late stage of processing. To test this hypothesis, 20 schizophrenia patients and 20 control subjects were tested in a visual oddball paradigm that was modified to allow measurement of the lateralized readiness potential (LRP), an index of stimulus-response translation processes. Difference waves were used to isolate the LRP and the P3 wave. Patients and control subjects exhibited virtually identical P3 difference waves, whereas the LRP difference wave was reduced in amplitude and delayed in latency in the patients. These results indicate that, at least in simple tasks, the delayed RTs observed in schizophrenia are primarily a consequence of impairments in the response selection and preparation processes that follow perception and categorization.     

Effects of caffeine on anticipatory control processes: evidence from a cued task-switch paradigm

Effects of caffeine on task switching were studied using ERPs in a cued task-switch paradigm. The need for advance preparation was manipulated by varying the number of task-set aspects that required switching. In a double-blind, within-subjects experiment, caffeine reduced shift costs compared to placebo. ERPs revealed a negative deflection developing within the preparatory interval, which was larger for shift than for repeat trials. Caffeine increased this shift-induced difference. Furthermore, shift costs increased as a function of the number of task-set features to be switched, but this pattern was not modulated by caffeine. The results suggest that caffeine improves task-switching performance by increasing general effects on task switching, related to task-nonspecific (rather than task-specific) anticipatory processes. Caffeine's actions may be mediated by dopaminergic changes in the striatum or anterior cingulate cortex.     

Visual mismatch negativity: New evidence from the equiprobable paradigm

In visual oddball studies, deviant compared to standard stimuli elicited a posterior negative ERP at around 100–250 ms. To determine the underlying processes of the negativity, we used the equiprobable sequence in which bar stimuli of five types of orientation were presented with equal probabilities (control 20% each) as well as the oddball sequence in which two stimuli with the closest orientation were presented with different probabilities (deviant 20% and standard 80%). Deviant compared to standard stimuli elicited two negativities at around 100–150 ms with no hemispheric dominance and 200–250 ms with right hemispheric dominance, while deviant compared to control stimuli elicited only a negativity at around 200–250 ms with right hemispheric dominance. These results suggest that the early negativity reflects refractory effect, while the late negativity reflects memory-comparison-based change detection effect (visual mismatch negativity).     

Anticipated action consequences as a nexus between action and perception: evidence from event-related potentials

We used high-density event-related potentials (ERP) in a modified flanker paradigm to study the role of anticipated action consequences in action planning and the role of anticipation in the perception of action consequences. Prior to the experiment, participants were trained to classify target letters in a four-alternative forced-choice task; another letter was presented as an effect following each response. After participants had thus acquired the response-effect contingencies, in the experiment effect letters were presented as flankers to target letters. Effect-compatible flankers were letters that were learned as effects of the correct response to the target; effect-incompatible ones were learned as effects of other responses; neutral flankers were never presented as action effects. To help distinguish early and late effects of flankers on target processing, flankers were presented either simultaneously with the target or after a delay. We found that effect-incompatible flankers resulted in longer, than other flankers, time between the onset of the response-locked lateralized readiness potential and the response, indicating extended motor processing. ERP evoked by the effect-incompatible flankers differed from those evoked by other flankers in early perceptual component P1 and in later frontal component P2 reflecting stimulus evaluation and conflict detection. These results show that anticipating action consequences involves brain systems ranging from perceptual to executive; anticipated action effects constitute a link between perception and action.     

Influence of trait-anxiety on inhibition function: Evidence from ERPs study

Patients suffering from anxiety disorder may experience a few problems in the inhibition function. Using event-related potentials, the current study investigated the differences between subjects with high versus low trait-anxiety when they tried to inhibit disturbances in novel emotional pictures in an oddball task. The results showed that P3 amplitudes evoked by negative pictures relative to neutral pictures were decreased in subjects with high as well as low anxiety. In the high-anxious group, P3 amplitudes were also decreased in the positive condition relative to the neutral condition, whereas in the low anxious group, P3 amplitudes showed no significant differences between the positive and neutral stimuli. This implies that people with high anxiety may exhibit some degree of over-inhibition in emotional processing as compared to people with low anxiety. These people tend to indiscriminately inhibit all types of disturbing emotional information.     

Partial information can be transmitted in an auditory channel: inferences from lateralized readiness potentials

With the two-choice go/no-go paradigm, we investigated whether timbre attribute can be transmitted as partial information from the stimulus identification stage to the response preparation stage in auditory tone processing. We manipulated two attributes of the stimulus: timbre (piano vs. violin) and acoustic intensity (soft vs. loud) to ensure an earlier processing of timbre than intensity. We associated the timbre attribute more with go trials. Results showed that lateralized readiness potentials (LRPs) were consistently elicited in no-go trials. This showed that the timbre attribute had been transmitted to the response preparation stage before the intensity attribute was processed in the stimuli identification stage. Such a result provides evidence for the continuous model and asynchronous discrete coding (ADC) model in information processing. We suggest that partial information can be transmitted in an auditory channel.     

Mask- and distractor-triggered inhibitory processes in the priming of motor responses: an EEG study

Masked stimuli presented near the threshold of conscious awareness may act as primes, affecting responses to subsequent targets. With arrows as primes and targets, the prime–mask–target sequence has been shown to evoke triphasic lateralized readiness potentials (LRP) with two phases of imbalance between hemispheres preceding the target‐related contralateral preponderance of negativity: first a negative, then a positive preponderance contralateral to prime direction. The present article provides evidence that the second wave is related to mask presentation and reflects inhibitory processing independent of reductions in prime visibility, even being evoked by nonmasking distractors that leave the prime fully accessible for consciousness. Of all hypotheses put forward to account for inverse effects in masked priming, this finding is most compatible with the mask‐triggered inhibition hypothesis suggested by P. Ja?kowski (2007) .     

Cognitive processes facilitated by contextual cueing: Evidence from event-related brain potentials

Finding a target in repeated search displays is faster than finding the same target in novel ones (contextual cueing). It is assumed that the visual context (the arrangement of the distracting objects) is used to guide attention efficiently to the target location. Alternatively, other factors, e.g., facilitation in early visual processing or in response selection, may play a role as well. In a contextual cueing experiment, participant's electrophysiological brain activity was recorded. Participants identified the target faster and more accurately in repeatedly presented displays. In this condition, the N2pc, a component reflecting the allocation of visual-spatial attention, was enhanced, indicating that attention was allocated more efficiently to those targets. However, also response-related processes, reflected by the LRP, were facilitated, indicating that guidance of attention cannot account for the entire contextual cueing benefit.     

Underlying mechanisms of the P3a task-difficulty effect

In three-stimulus oddball studies, even typical deviant stimuli elicited a large P3a event-related brain potential (ERP) when target/standard discrimination was difficult. To investigate the underlying mechanisms, the effects of task difficulty on early deviant-related ERPs were assessed. Four visual stimuli defined by an orthogonal combination of task-relevant size (nontarget 80%, target 20%) and task-irrelevant luminance (standard 80%, deviant 20%) were presented randomly, where two task difficulties (easy, difficult) were defined by target/nontarget discriminability. An increase in task difficulty enhanced P3a as well as a posterior negativity (change-related negativity) and an anterior positivity (frontal positivity) elicited by deviant nontarget stimuli. These results suggest that attentional modulation of refractoriness-based rareness detection and an attention-triggering process underlie the P3a task-difficulty effect.     

Age differences in task switching and response monitoring: evidence from ERPs

This study investigates age differences in the flexible adaptation to changing demands on task switching and conflict processing. We applied a cued task-switching version of the Stroop task and manipulated the ratio of conflict trials. During task preparation, the P300 varied as a function of conflict ratio and a later positive component was larger for switch than non-switch trials. Stimulus-related conflict processing as indicated by a negativity for incompatible trials (Ni) was delayed for older adults. Moreover, the Ni varied as a function of conflict ratio and was larger for switch than for non-switch trials. Age differences were also obtained in the correct response negativity (CRN). CRN was larger on incompatible trials and this CRN-compatibility effect was enhanced when incompatible trials were infrequent in younger, but not in older adults. Our findings suggest impairments of older adults primarily in response-related conflict processing and in the flexible adaptation to changing task contexts.     

Crossmodal links in spatial attention are mediated by supramodal control processes: evidence from event-related potentials

Crossmodal links in spatial attention were studied in an experiment where participants had to detect peripheral tactile or visual targets on the attended side, while ignoring all stimuli on the unattended side and in the currently irrelevant modality. Both relevant locations and relevant modalities were specified on a trial-by-trial basis by auditory precues. Spatial orienting in the cue-target interval was reflected in anterior negativities and occipital positivities contralateral to the cued side, either when vision or touch was cued as relevant. These effects resembled previously reported ERP modulations during shifts of visual attention, implicating supramodal mechanisms in the control of spatial attention and demonstrating their independence of cue modality. Early effects of spatial attention on somatosensory and visual ERPs were of equivalent size for currently relevant and irrelevant modalities. Results support the idea that crossmodal links in spatial attention are mediated by supramodal control mechanisms.     

述情障碍者情绪启动效应的ERPs特征

目的:分析述情障碍者情绪启动中的ERPs特征,探讨述情障碍者情绪自动加工缺陷的神经机制。方法:采用TAS-20中文版筛选出述情障碍者与非述情障碍者进入情绪启动实验。以阈下或阈上方式呈现启动图片,要求受试对目标图片做出正负性的判断,记录受试ERPs数据。结果:在阈上启动任务中,述情障碍组的P2波幅和"启动-非启动"差异波N600波幅均显著小于非述情障碍组的波幅,而阈下启动任务中的P2、P3潜伏期与波幅及N600波幅则均不存在显著组间差异。结论:本研究进一步支持述情障碍者对无意识感知的情绪刺激的自动加工是完整的,而对意识到的情绪刺激的自动加工存在明显的缺陷。     

Electrophysiological evidence of feature-based inhibition of focused attention across consecutive trials

Monitoring the visual environment for targets has evolutionary and ecological significance. Exploration of the visual scene can be hypothesized to use "saliency maps" representing the priorities allocated to different locations and features, which change dynamically based on previous experience. This is supported by the observation that sequential effects influence the speed and accuracy of visual search tasks. Yet, the mechanisms underlying these effects are not well understood. Here we used electrophysiological methods to identify some of the mechanisms underlying a specific sequential effect—the distractor previewing effect (DPE). We found that the DPE is correlated with electrophysiological indices of attention allocation but not with sensory or motor components, suggesting that the DPE is related to attentional phenomena, rather than perceptual or motor levels of processing.     

P300 and handedness: On the possible contribution of corpus callosal size to ERPs

The P300 event-related potential (ERP) was elicited in left- and right-handed young adult male and female participants ( n = 20Ygroup) with both auditory and visual stimulus discrimination tasks that varied systematically in difficulty. P300 amplitude was larger across all task conditions for left- than for right-handed participants at anterior and central electrode sites. P300 latency was shorter across all task conditions for left- than for right-handers. Task difficulty did not affect the ERP handedness differences. Male and female subjects demonstrated comparable ERP handedness effects, although smaller P300 components were obtained for males than for females. When considered in the context of corpus callosal size differences for left- versus right-handed and male versus female participants, the findings suggest that the P300 reflects callosal size and interhemispheric transmission efficacy.     

Modern Mind-Brain Reading: Psychophysiology, Physiology, and Cognition

This paper reviews the actual and potential benefits of a marriage between cognitive psychology and psychophysiology. Psychophysiological measures, particularly those of the event-related brain potential, can be used as markers for psychological events and physiological events. Thus, they can serve as "windows" on the mind and as "windows" on the brain. These ideas are illustrated in the context of a series of studies utilizing the lateralized readiness potential, a measure of electrical brain activity that is related to preparation for movement. This measure has been used to illuminate presetting processes that prepare the motor system for action, to demonstrate the presence of the transmission of partial information in the cognitive system, and to identify processes responsible for the inhibition of responses. The lateralized readiness potential appears to reflect activity in motor areas of cortex. Thus, this measure, along with other psychophysiological measures, can be used to understand how the functions of the mind are implemented in the brain.     

Love withdrawal is related to heightened processing of faces with emotional expressions and incongruent emotional feedback: evidence from ERPs

Parental use of love withdrawal is thought to affect children's later psychological functioning because it creates a link between children's performance and relational consequences. To investigate whether love withdrawal is also associated with the underlying level of basic information processing in the brain, we studied event-related potentials to feedback stimuli that combined performance feedback with emotional facial expressions. We focused on the VPP (face processing) and N400 (incongruence processing). More maternal use of love withdrawal was related to more positive VPP amplitudes, larger effects of the emotional facial expression on VPP amplitude, and more negative N400 responses to incongruent combinations of feedback and facial expressions. Our findings suggest a heightened processing of faces with emotional expressions and greater sensitivity to incongruence between feedback and facial expression in individuals who experienced more love withdrawal.