Comparison of event-related potentials in attentional blink and repetition blindness

Attending to the first target in rapid serial visual presentation (RSVP) interferes with processing of the second target so that the participants fail to recognize the second target if the targets are separated by a stimulus onset asynchrony of 200-500 ms. This phenomenon is attentional blink (AB). Repetition blindness (RB) is an additional difficulty to recognize the second occurrence of the same stimulus in RSVP. A controversial issue in studies of both deficits is the processing level at which they occur. To compare the timing and mechanisms of AB and RB directly during the same RSVP stream, we recorded event-related potentials (ERPs) in response to repeated and unrepeated targets. Comparable to earlier ERP studies on visual awareness, the results showed for both types of targets a negative amplitude difference between ERPs to consciously recognized and unrecognized targets during 250-350 ms from stimulus onset, suggesting that both AB and RB are associated with deficits of conscious perception, occurring at earlier stages than access to working memory. However, the perceptual deficit in RB is more severe, which may be related to higher overall negativity in response to repeated targets observed 150-300 ms after stimulus onset, suggesting stronger cortical baseline activation and higher perceptual threshold for repeated targets as compared with unrepeated ones.

Updating P300: an integrative theory of P3a and P3b

The empirical and theoretical development of the P300 event-related brain potential (ERP) is reviewed by considering factors that contribute to its amplitude, latency, and general characteristics. The neuropsychological origins of the P3a and P3b subcomponents are detailed, and how target/standard discrimination difficulty modulates scalp topography is discussed. The neural loci of P3a and P3b generation are outlined, and a cognitive model is proffered: P3a originates from stimulus-driven frontal attention mechanisms during task processing, whereas P3b originates from temporal-parietal activity associated with attention and appears related to subsequent memory processing. Neurotransmitter actions associating P3a to frontal/dopaminergic and P3b to parietal/norepinephrine pathways are highlighted. Neuroinhibition is suggested as an overarching theoretical mechanism for P300, which is elicited when stimulus detection engages memory operations.

Short-term consolidation of visual patterns interferes with visuo-spatial attention: converging evidence from human electrophysiology

In order to investigate the interplay between visuo-spatial attention and central attention, we varied the relative probability (25% vs. 75%) of the responses to lateralized targets in an attentional blink paradigm. When the first target was associated with a less probable response, we observed a larger attentional blink, that is, a general reduction in accuracy for the second target. The efficiency of deployment of spatial attention to the second target was also reduced as a function of the response frequency for the first target. Both the N2pc, an event-related potential (ERP) associated with the deployment of attention in visual space, and the SPCN (sustained posterior contralateral negativity), an ERP associated with the maintenance of information in visual short-term memory, time-locked to T2 were significantly reduced when the first target was associated with a less frequent response. Furthermore, the P3 ERP to T2 was abolished when the response to T1 was rare but not when it was frequent. The results show that the association of T1 to either a rare or frequent response causes significant interference with the deployment of visual spatial attention to T2, and with the short-term consolidation of T2 into visual short-term memory.

P3 latency shifts in the attentional blink: Further evidence for second target processing postponement

A rapid serial visual presentation technique was used to display sequentially two targets, T1 and T2, and monitor P3 amplitude and latency variations associated with the attentional blink (AB) effect. A red T1 digit was embedded on each trial in a sequence of black letters. T2 was either masked by a trailing stimulus or not masked. T1 had to be identified on a proportion of trials, or ignored in other trials. T2 was the black letter 'E' on 20% of the trials, or any other non-'E' black letter in the other 80% of the trials. A delayed 'E' detection task was required at the end of each trial. An AB was observed when T1 had to be reported and T2 was masked. The AB effect was associated with a sizable amplitude reduction of the P3 component time locked to T2 onset. When T2 was not masked, no AB or P3 amplitude variations were observed. When T1 had to be reported, a delayed P3 peak latency was observed at short compared to long T1-T2 intervals. No effect of T1-T2 interval was observed on the T2-locked P3 peak latency when T1 could be ignored. Taken together these findings provide converging evidence in support of temporal attention models bridging behavior and electrophysiology that postulate a direct link between the cause of the AB effect and the sources of both amplitude and latency variations in the T2-locked P3 component.

Brain electrical correlates of dimensional weighting: An ERP study

In visual search, there is a reaction time (RT) cost for targets on a given trial if the previous target was defined in a different dimension. According to the "dimension-weighting" account (Müller, Heller, & Ziegler, 1995), limited attentional weight needs to be shifted to the new dimension, resulting in slower RTs. The present study aimed at identifying brain electrical correlates associated with the weight shift. Analyses of ERPs revealed several components to reflect dimension changes whether the task was to detect the target or to identify its defining dimension. N2 amplitudes were more negative whenever the dimension changed. The P3 exhibited latency differences that mirrored RTs in both tasks, but the amplitudes showed no direct relation to stimulus- or response-related processes. Finally, slow-wave amplitudes were enhanced for dimension changes. Taken together, the results provide support for relatively early, perceptual processes underlying dimension change costs.

Normative Variation of P3a and P3b from a Large Sample

Abstract. The P3a and P3b components were elicited in 120 (60 females, 60 males) young adults using a visual three-stimulus event-related brain potential (ERP) oddball paradigm in which subjects responded to an infrequent target. The major purpose of the paper was to provide a statistically strong characterization of these related P300 subcomponents. P3a components were obtained from the infrequently presented distracter stimulus, which was a large blue square. P3b components were obtained from the target stimulus, which was a blue circle that differed slightly in diameter from the standard stimulus blue circle. Amplitude measures demonstrated that P3a was maximum at Cz, and P3b was maximum at Pz; latency measures increased for both potentials from frontal to parietal recording sites. P3a and P3b from females were larger and later than those from male subjects, with topographic and appreciable individual difference variability observed. P3a was generally unrelated to response time. P3b amplitude was negatively correlated over right frontal areas with P3b latency and positively correlated over right parietal areas to response time. Theoretical implications are discussed.

Effective connectivity in target stimulus processing: a dynamic causal modeling study of visual oddball task

PURPOSE

To investigate the fundamental connectivity architecture of neural structures involved in the goal-directed processing of target events.

METHODS

Twenty healthy volunteers underwent event-related functional magnetic resonance imaging (fMRI) while performing a standard oddball task. In the task, two types of visual stimuli - rare (target) and frequent - were randomly presented, and subjects were instructed to mentally count the target stimuli. Dynamic causal modeling (DCM), in combination with Bayes factors was used to compare competing neurophysiological models with different intrinsic connectivity structures and input regions within the network of brain regions underlying target stimulus processing.

RESULTS

Conventional analysis of fMRI data revealed significantly greater activation in response to the target stimuli (in comparison to the frequent stimuli) in several brain regions, including the intraparietal sulci and supramarginal gyri, the anterior and posterior cingulate gyri, the inferior and middle frontal gyri, the superior temporal sulcus, the precuneus/cuneus, and the subcortical grey matter (caudate and thalamus). The most extensive cortical activations were found in the right intraparietal sulcus (IPS), the anterior cingulate cortex (ACC), and the right lateral prefrontal cortex (PFC). These three regions were entered into the DCM. A comparison on a group level revealed that the dynamic causal models in which the ACC and alternatively the IPS served as input regions were superior to a model in which the PFC was assumed to receive external inputs. No significant difference was observed between the fully connected models with ACC and IPS as input regions. Subsequent analysis of the intrinsic connectivity within two investigated models (IPS and ACC) disclosed significant parallel forward connections from the IPS to the frontal areas and from the ACC to the PFC and the IPS.

CONCLUSION

Our findings indicate that during target stimulus processing there is a bidirectional frontoparietal information flow, very likely reflecting parallel activation of two distinct but partially overlapping attentional or attentional/event-encoding neural systems. Additionally, a simple hierarchy within the right frontal lobe is suggested with the ACC exerting influence over the PFC.

Scalp Topography and Intracerebral Sources for ERPs Recorded During Auditory Target Detection

The goal of this study was to measure the scalp topography of the event-related potentials (ERPs) during the detection of improbable auditory targets and to determine the intracerebral sources of these potentials. ERPs were recorded when subjects listened to a sequence of spoken words and detected occasional (p = 0.2) targets defined either by the gender of the speaker (male/female) or the meaning of the word (animate/inanimate). Waveforms were evaluated in relation to category (target versus standard) and task (voice versus semantic). Dipole source analysis was performed using locations obtained from fMRI. Fronto-central negative waves (N450 and N600 ms) generated by sources in both the auditory cortex and frontal regions were larger for semantic tasks and larger over the left hemisphere. A large parieto-occipital positive wave (P700) occurring with a peak latency about 150 ms before the reaction time was mainly generated in the left temporo-parietal regions for the semantic task and bilaterally for the voice task. About 300 ms after the P700, a highly lateralized right temporo-parietal positive wave P1000r occurred with a source in the right temporo-parietal area. These results indicate three distinct physiological processes underlie the detection of auditory targets. Perceptual discrimination is related to interactions between the frontal and temporal regions, stimulus-response association occurs in the temporo-parietal regions and post-perceptual processing in the right temporo-parietal region.

Precursors of Insight in Event-related Brain Potentials

Event-related potentials (ERPs) were investigated to find precursors of insightful behavior. Participants had to process successive pairs in strings of digits to obtain a final response in each trial. Within the sequence of five responses required in each trial, the last two responses mirrored the two preceding ones. This hidden regularity, allowing for shortcutting each trial from five to two responses, was discovered by 6 out of 26 participants. Both groups, solvers and nonsolvers, implicitly learned the regularity, reflected by faster responses to the repeated, predictable responses, but this differential effect was larger in solvers, whereas nonsolvers became unspecifically faster with all responses. Several ERP components were larger in solvers than in nonsolvers from the outset: slow positive wave, frontocentral P3a, anterior N1 to those digits that triggered the critical repeating responses, and P3b to the digit that evoked the immediately repeating response. Being already present in the first block, these effects were early precursors of insightful behavior. This early occurrence suggests that participants who will gain insight may be distinguished beforehand by their individual characteristics.

Motor-response generation as a source of aging-related behavioural slowing in choice-reaction tasks

OBJECTIVE

To analyze the effects of stimulus-response (SR) processing modes on different central stages of sensorimotor processing in order to evaluate their contribution to aging-related behavioural slowing.

METHODS

Components of stimulus- and response-related potentials (ERPs/RRPs) and lateralized readiness potentials (LRPs) were analyzed in two groups of young (mean 22.5 years) and older adults (mean 58.3 years) during an auditory and a visual four-choice-reaction task.

RESULTS

(1) Reaction time (RT) depended on the SR type, indicating SR-specific differences in processing, which did not vary with age. (2) For each SR type, the RT increased with age. RT slowing was not accompanied by significant delays in early stimulus processing (as reflected by P1 and N1 latencies) nor in response selection (as reflected by the onset of stimulus-locked LRP), but resulted from a prolongation of contralateral motor activity during motor response execution indexed by earlier, longer durated and larger motor-related potentials in older adults. These aging effects were observed for each SR type.

CONCLUSION

In a four-choice-reaction task, (1) task complexity rather than differences in cognitive strategy or activation patterns subserving SR-specific processing leads to response slowing with aging and (2) the most plausible contributor to this slowing is the cortical response generation system.

Contralateral and ipsilateral motor activation in visual simple reaction time: a test of the hemispheric coactivation model

Motor potentials contralateral versus ipsilateral to the responding hand were examined in a visual simple reaction time (RT) experiment in order to test the hemispheric coactivation model of Miller (Cogn Psychol 49:118-154, 2004). Visual stimuli were presented on the left side of fixation, on the right side, or on both sides, and in the RT task participants had to respond as quickly as possible to the onset of any stimulus. The same stimulus displays were also presented in a counting task, for which participants had merely to count the stimuli. Hemisphere-specific movement-related potentials contralateral and ipsilateral to the responding hand were isolated by subtracting count-task ERPs from RT-task ERPs. Consistent with the hemispheric coactivation model, there was evidence of movement-related ipsilateral positivity as well as contralateral negativity, suggesting that the motor areas of both hemispheres contribute to response initiation in simple RT. The distinction between contralateral and ipsilateral motor activation appears useful in clarifying the roles of the two hemispheres in response initiation.

The effect of sleepiness on performance monitoring: I know what I am doing, but do I care?

The behavioral, cognitive, and psychophysiological effects of extended wakefulness are well known. As time awake increases, errors become more common and are often attributed to lapses in attention. Such lapses can be reflected in the error-related negativity (Ne/ERN), a negative electroencephalogram deflection occurring after errors and is thought to be related to error detection or response conflict. Following the Ne/ERN, a positive deflection (error positivity, Pe) is also observed and is thought to reflect further evaluation of the error. To elicit Ne/ERNs, the Eriksen Flanker Task was administered to 17 women (aged 19-45 years) at two levels of alertness (4 and 20 h awake). After extended wakefulness, participants reported being subjectively sleepier and performing worse, but showed no significant difference in subjective effort. Across alertness conditions, they reported a similar number of subjective errors which closely matched an objective analysis of the errors. The Ne/ERN was not significantly reduced by sleepiness in contrast to the Pe which was reduced. Behavioral slowing after errors was larger in the alert than in the sleepy condition. These results show that after 20 h of wakefulness, individuals are reacting to their errors. However, further evaluation of the error, and remediation of these errors may be impaired despite continued effort.

On the relation of movement-related potentials to the go/no-go effect on P3

According to Simson et al. [Simson, R., Vaughan, H.G., Jr., Ritter, W., 1977. The scalp topography of potentials in auditory and visual go/nogo tasks. Electroencephalography and Clinical Neurophysiology 43, 864-875], the difference between no-go P3 and go-P3 (the go/no-go effect) is due to overlap of P3 onto the return of the preceding contingent negative variation (CNV) in no-go trials and onto the continuing CNV in go trials. Similarly, according to Kok [Kok, A., 1986. Effects of degradation of visual stimuli on components of the event-related potential (ERP) in go/nogo reaction tasks. Biological Psychology 23, 21-38], the go/no-go effect is due to movement-related negative potentials, in particular contralateral negativity, adding with P3 in go trials. To investigate these notions, we studied how CNV, go-P3 and no-go P3 are lateralized at fronto-central sites when the side of the response varies across trials, comparing these effects between hand movements and eye movements and delineating them more precisely for hand movements with multichannel recordings. The go/no-go effect was larger and contralaterally lateralized with hand movements than with eye movements. Dipole analysis dissected its components into a large contribution of the medial cingulate gyrus, into activity of motor areas contralateral to the cued hand and a left-frontal source. Motor-related portions of the effect seemed to build upon and extend motor-related components included in CNV. Results provide support for the notion that the go/no-go effect is related to movement-related potentials. We suggest that go-P3 and no-go P3 are characterized by addition and reduction of motor-related activation to the core P3.

Bistable perception -- along the processing chain from ambiguous visual input to a stable percept

The observation of an ambiguous figure leads to spontaneous perceptual reversals while the observed picture stays unchanged. Some ERP studies on ambiguous figures report a P300-like component correlated with perceptual reversals supporting a top-down explanation, while other studies found early visual ERP components supporting a bottom-up explanation. Based on an experimental paradigm that permits a high temporal resolution of the endogenous reversal event, we compared endogenous Necker-cube reversals with exogenously-induced reversals of unambiguous cube variants. For both reversal types, we found a chain of ERP components with the following characteristics: (1) An early occipital ERP component (130 ms) is restricted to endogenous reversals. (2) All subsequent components also appear with exogenously-induced reversals, however 40-90 ms earlier than their endogenous counterparts. (3) The latency difference between reversal types is also reflected in the timing of manual reactions, which occur 100-130 ms after P300-like components. The results suggest that the P300-like component is the same as found in other ERP studies on ambiguous figures. This component does not reflect the reversal per se, but rather its cognitive analysis, 300 ms after a change of the representation in early visual areas. The presented ERP chains integrate the different ERP results and allow to pinpoint the steps where top-down mechanisms begin to exert their influence.

Task reconfiguration and carryover in task switching: An event-related potential study

This study investigated the electrophysiological correlates of the processes involved in task switching. A pair-wise task-switching paradigm was used where each trial comprised two tasks that were either the same (task repeat) or different (task switch). In the paradigm, task-switch and repeat trials are compared in conditions of foreknowledge and non-foreknowledge of the forthcoming task type and during different response-stimulus intervals (RSIs). The results of this study show that, before the second task began in a task-pair trial, i.e., during the RSI, there was a CNV-like negativity for all trials. This indicates a general anticipatory effect. In foreknowledge conditions, there is an additional switch-specific reconfiguration process followed by a task-specific (including both switch- and repeat-related) preparatory process. During the post-task 2 stage, P3b was found to be smaller in switch trials than in repeat trials. Such differential P3b between switch and repeat trials appeared earlier and larger in foreknowledge than in non-foreknowledge conditions. The results of this study support the existence of advance preparation and uphold the role of carryover effects in task switching.

Spatiotemporal overlap between brain activation related to saccade preparation and attentional orienting

Recent brain imaging studies provided evidence that the brain areas involved with attentional orienting and the preparation of saccades largely overlap, which may indicate that focusing attention at a specific location can be considered as an unexecuted saccade towards that location (i.e. the premotor theory of attention). Alternatively, it may be proposed that attentional orienting is simply relevant for preparing saccades, but the two processes may also be completely unrelated. In two experiments, we examined temporal activation of brain areas by measuring the electroencephalogram. Central cues indicated the likely side (left or right) at which a to-be-attended target would occur, or to which a saccade had to be prepared. Cue direction-related activity was determined, time-locked to cue onset. In addition, in our second experiment, delayed saccades had to be carried out, which allows to focus on processes strongly related to saccade execution. In nearly all tasks, an early directing attention negativity (EDAN), an anterior directing attention negativity (ADAN), and a late directing attention positivity (LDAP) were observed, time-locked to cue onset. Source analyses supported the view that this activity probably originates from areas within the ventral intraparietal sulcus (vIPS) and the frontal eye fields (FEF). The saccade-locked analysis also indicated that the FEF plays an important role in triggering saccades, but the role of vIPS appears to be minimal. The latter finding disfavors the premotor theory of attention, as it suggests that the relation between attention and action is less direct.

Differences Between Intention-Based and Stimulus-Based Actions

Abstract: Actions carried out in response to exogenous stimuli and actions selected endogenously on the basis of intentions were compared in terms of their behavioral (movement timing) and electrophysiological (EEG) profiles. Participants performed a temporal bisection task that involved making left or right key presses at the midpoint between isochronous pacing signals (a sequence of centrally-presented letters). In separate conditions, the identity of each letter either (1) prescribed the location of the subsequent key press response (stimulus-based) or (2) was determined by the location of the preceding key press, in which case participants were instructed to generate a random sequence of letters (intention-based). The behavioral results indicated that stimulus-based movements occurred earlier in time than intention-based movements. The EEG results revealed that activity reflecting stimulus evaluation and response selection was most pronounced in the stimulus-based condition, whereas activity associated with the general readiness to act was strongest in the intention-based condition. Together, the behavioral and electrophysiological findings provide evidence for two modes of action planning, one mediated by stimulus-response bindings and the other by action-effect bindings. The comparison of our results to those of an earlier study ( Waszak et al., 2005 ) that employed spatially congruent visuo-motor mappings rather than symbolic visuo-motor mappings suggests that intention-based actions are controlled by similar neural pathways in both cases, but stimulus-based actions are not.