P3b Component Research Articles

P3b as an electroencephalographic index of automatic associations of exercise-related images

ObjectiveInterest in automatic associations of exercise and physical activity as potential contributors to behavior is rising. However, the measurement of these associations presents a challenge, since the reliability and validity of behavioral tests (despite their widespread usage) is unsatisfactory by most accounts. As a possible alternative, an electroencephalographic (EEG) index (i.e., P3b amplitude) was examined in the present study. DesignWe used a mixed-factor design, with one group of insufficiently and one group of sufficiently physically active participants being compared across different experimental conditions. MethodsThirty-seven insufficiently and thirty-six sufficiently active participants viewed exercise-related images presented within series of negative, neutral, or positive images and rated all images as negative (unpleasant) or positive (pleasant) while EEG recordings were obtained. The amplitude of the P3b component of the EEG-derived event-related potential, time-locked to the onset of exercise images in each context (series), was extracted as the dependent variable. ResultsInsufficiently active participants rated the exercise-related images as neutral-to-positive, whereas sufficiently active participants rated the images as positive. However, all participants exhibited the smallest P3b amplitude when the images were presented in the neutral context, suggesting that the images were registering as neutral. ConclusionExercise-related images may evoke neutral automatic associations, but these associations may differ from how individuals reflectively rate the same images. P3b amplitude may be useful in detecting such discrepancies and potentially a promising (evidence-based) option for assessing automatic associations of exercise stimuli.

Increasing Objective Cardiometabolic Burden Associated With Attenuations in the P3b Event-Related Potential Component in Older Adults.

Cardiometabolic diseases and risk factors increase the risk of late-life cognitive impairment and dementia and have also been associated with detrimental gray and white matter changes. However, the functional brain changes associated with cardiometabolic health in late-life are unclear. We sought to characterize these functional changes by recording event-related potentials (ERPs) during an n-back working memory task (0, 1, and 2 back) in 85 adults (60% female) between 50 and 80 years of age. Due to a stratified recruitment approach, participants varied widely in relation to cognitive function and cardiometabolic health. Standard and objective cut-offs for high blood glucose, waist to hip ratio (i.e., obesity), high blood cholesterol, and hypertension were employed to generate a summative score for cardiometabolic burden (none, one, or two or more above cut-off). Mixed effects modeling (covarying for age and gender) revealed no statistically significant associations between cardiometabolic burden and visual P1 and N1 component amplitudes. There was a significant effect for the P3b component: as cardiometabolic burden increased, P3b amplitude decreased. We show that cardiometabolic factors related to the development of cognitive impairment and dementia in late-life associate with brain activity, as recorded via ERPs. Findings have relevance for the monitoring of lifestyle interventions (typically targeting cardiometabolic factors) in aging, as ERPs may provide a more sensitive measure of change than cognitive performance. Further, our results raise questions related to the findings of a broad range of ERP studies where the groups compared may differ in their cardiometabolic health status (not only in psychological symptomatology).

Unconscious perception of one's own name modulates amplitude of the P3B ERP component

The P3 event-related potential has been known for over 50 years, but its function is still a matter of ongoing debate. Current theories interpret P3b either as a correlate of perceptual consciousness, or as reflecting cognitive processes, like working memory and executive functions. Unexpectedly, recent studies indicate that P3b might occur in response to unconsciously presented stimuli which, if further replicated, will be important for defining its functional role. Therefore, in the present study we investigated the P3b component in response to participants' own name - a stimulus which is subjectively extremely salient and known to evoke a robust P3b response. The self-name and control (other) names were presented supra- and subliminally (backward-masked), in a subjective rating task and in a forced-choice identification task. We found that a consciously perceived self-name evoked a P3b of larger amplitude than the other-name in both tasks, which confirms that the self-name was processed preferentially. When the self-name was presented subliminally it was associated with larger P3b amplitude than the other-name in the identification task, but not in the subjective rating task. This indicates that a salient stimulus can in principle modulate the P3b amplitude even when processed outside of awareness, but also that subliminal processing depends on the task-set and top-down factors. Taken as a whole, our results provide evidence against the interpretation of P3b as a correlate of consciousness (and more generally conflict with the Global Workspace Theory) and will allow a more precise description of the relation between P3b and cognitive processes.

MEG reveals preference specific increases of sexual-image-evoked responses in paedophilic sexual offenders and healthy controls

Objectives Paedophilic disorder is characterised by sexual attraction towards children. Classification of a counterpart as sexually attractive likely occurs rapidly, and involves both conscious and unconscious attentional and cognitive processes. Magnetoencephalography (MEG) is an imaging method especially well-suited to examine visual and attentional processes triggered by sexual images within the range of milliseconds. Methods We investigated brain responses to sexual images depicting adults (frequent) and children (infrequent stimulus) in seventeen paedophilic patients with a history of child sexual offending (P + CSO) and twenty healthy controls (HC) during a passive visual oddball paradigm. Event-related fields (ERF) were measured to extract the magnetic visual mismatch negativity (vMMNm), and how it relates to the processing of different classes of sexual stimuli. Results P + CSO exhibited significantly longer vMMNm latencies (100–180 ms post-stimulus) than HC. Moreover, P + CSO showed widespread increased amplitudes in response to child images starting from P3a and P3b components and lasting up to 400 ms post-stimulus presentation localised in frontal and temporal brain regions. Conclusions This study uncovers the first MEG differences in automatic change detection between P + CSO and HC during the presentation of subliminal sexual images of adults and children, contributing towards a better understanding of the neurobiological processes of P + CSO.

Lack of awareness despite complex visual processing: Evidence from event-related potentials in a case of selective metamorphopsia

Visual awareness is thought to result from integration of low- and high-level processing; instances of integration failure provide a crucial window into the cognitive and neural bases of awareness. We present neurophysiological evidence of complex cognitive processing in the absence of awareness, raising questions about the conditions necessary for visual awareness. We describe an individual with a neurodegenerative disease who exhibits impaired visual awareness for the digits 2 to 9, and stimuli presented in close proximity to these digits, due to perceptual distortion. We identified robust event-related potential responses indicating 1) face detection with the N170 component and 2) task-dependent target-word detection with the P3b component, despite no awareness of the presence of faces or target words. These data force us to reconsider the relationship between neural processing and visual awareness; even stimuli processed by a workspace-like cognitive system can remain inaccessible to awareness. We discuss how this finding challenges and constrains theories of visual awareness.

No effect of target probability on P3b amplitudes

Event probability has been traditionally regarded as the major determinant of P3b amplitudes, with amplitudes increasing when stimuli are less likely. Here we show in a simple variant of the continuous performance task that this “oddball effect” does not universally apply. Stimuli were a continuous series of (A or B) –> (X or Y) pairs, with the letter X requiring a key-press response and occurring in 80% of trials after A and in 20% after B (vice versa the Y). P3b amplitudes were equally large with probable and improbable occurrence of X. This was in contrast to visual Mismatch Negativity which was consistently larger with less probable stimuli, and also in contrast to no-go P3 amplitudes, which were larger with improbable than probable Y. The only effect on P3b amplitude was due to stimulus onset asynchronies (SOA): P3b was larger with SOAs of 2000 ms compared to 1500 ms. This result dovetails with previous evidence in the oddball task that the main determinant of the oddball effect is not event probability but rather time interval between stimuli. The absence of probability effects on P3b was in sharp contrast to the presence of these effects on no-go P3. Implications are discussed for theories about the psychological meaning of the P3b component.

Risk prediction error signaling: A two-component response?

Organisms use rewards to navigate and adapt to (uncertain) environments. Error-based learning about rewards is supported by the dopaminergic system, which is thought to signal reward prediction errors to make adjustments to past predictions. More recently, the phasic dopamine response was suggested to have two components: the first rapid component is thought to signal the detection of a potentially rewarding stimulus; the second, slightly later component characterizes the stimulus by its reward prediction error. Error-based learning signals have also been found for risk. However, whether the neural generators of these signals employ a two-component coding scheme like the dopaminergic system is unknown. Here, using human high density EEG, we ask whether risk learning, or more generally speaking surprise-based learning under uncertainty, is similarly comprised of two temporally dissociable components. Using a simple card game, we show that the risk prediction error is reflected in the amplitude of the P3b component. This P3b modulation is preceded by an earlier component, that is modulated by the stimulus salience. Source analyses are compatible with the idea that both the early salience signal and the later risk prediction error signal are generated in insular, frontal, and temporal cortex. The identified sources are parts of the risk processing network that receives input from noradrenergic cells in the locus coeruleus. Finally, the P3b amplitude modulation is mirrored by an analogous modulation of pupil size, which is consistent with the idea that both the P3b and pupil size indirectly reflect locus coeruleus activity.

The response relevance of visual stimuli modulates the P3 component and the underlying sensorimotor network

The functional meaning and neural basis of the P3b component of ERPs are still under debate. One of the main issues is whether P3b reflects only stimulus-related processes (stimulus evaluation hypothesis) or response-related processes as well (stimulus-response or S-R link activation hypothesis). Here, we conducted an EEG experiment examining whether P3b may indeed reflect an S-R link activation, followed by an fMRI experiment in which we explored the brain areas and functional connectivity possibly constituting the neural basis of these sensorimotor links. In both experiments, two successive visual stimuli, S1 and S2, were presented with a 1 sec interval, and responses were defined either by S1 or S2, while participants responded only after S2 onset. The obtained EEG results suggest that P3b may be interpreted in terms of the S-R link activation account, although further studies are needed to disentangle P3-related activity from overlapping anticipatory activity. The obtained fMRI results showed that processing of the relevant S1 involved activation of a distributed postero-anterior sensorimotor network, and increased strength of functional connectivity within this network. This network may underlie activation of the S-R links, thus possibly also the P3b component, forming a bridging step between sensory encoding and response execution.

Motivational effects on brain activity: need for closure moderates the impact of task uncertainty on engagement-related P3b.

Need for cognitive closure (NFC), that is, individual's aversion toward uncertainty and the desire to reduce it quickly usually manifests in effort minimizing cognitive strategies. Recent studies, however, demonstrated that it is also linked with laborious processing when the task itself induces uncertainty. Although this pattern was observed when testing behaviors and cardiovascular activity, it has never been tested on a neurocognitive level. To fill this gap, we investigate whether NFC moderates the impact of task uncertainty on engagement-related P3b component of brain activity. In the experiment, we recorded the electroencephalographic activity of the brain while participants performed a sampling task which provides uncertainty manipulation within participants. We also manipulated NFC between participants. As predicted, we did not find any differences between high and low NFC participants in the P3b component at lower levels of uncertainty. However, at the highest level of uncertainty, the P3b component decreases significantly among low but not high NFC participants. That is because gaining certainty and achieving closure is not a critical epistemic goal for low NFC and thus, exerting extra effort to gain certainty is not justified.

Acute Moderate-Intensity Exercise Generally Enhances Attentional Resources Related to Perceptual Processing

The present study aimed to investigate whether acute moderate-intensity exercise led to a selective effect on executive function tasks or general effect on cognitive tasks that involve executive function and basic information processing in young adults. Besides, we also aimed to examine acute exercise’s effect on multiple ERP components (e.g., P2, N2, P3b, and N450) to expand previous research. Seventy-two young adults were randomly assigned to the exercise or control groups. The Stroop task was administrated before and after treatments (exercise or reading), and the P2, N2, P3b, and N450 components of the Event-Related Potential (ERP) waveform were recorded and analyzed. Larger P2 amplitudes on both congruent and incongruent tasks were observed following acute exercise. Acute exercise did not influence accuracy or response time, and no effects on N2, P3b, and N450 components were found. These findings suggest that acute moderate-intensity exercise may have a generally beneficial effect on mobilization of attentional resources related to perceptual processing and exercise-related physiological arousal.

IS COMBINED TRAINING MORE EFFECTIVE THAN SINGLE-DOMAIN TRAINING: A RANDOMIZED CONTROLLED TRIAL WITH OLDER ADULTS

Previous research suggests that both cognitive training and physical exercise help to maintain brain health and cognitive functions that decline with age. The main objectives of this four-arms RCT are (1) to investigate the synergetic effects of a group-based multidomain training program that combines cognitive video-game training with physical exercise, in comparison to those produced by cognitive training combined with physical control activity, physical training combined with cognitive control activity, or a combination of both control activities; (2) to investigate in a memory-based task switching task whether event Related Potential (ERP) latencies of the P2 component are shorter, and N2 and P3b components are enhanced after training; and (3) to find out whether possible enhancements persist after a 3-month period without training. One hundred and twenty participants will be randomly assigned to one of the four combinations of cognitive training and physical exercise. The cognitive component will be either video-game training (cognitive intervention, CI) or video games not specifically designed to train cognition (cognitive control, CC). The physical exercise component will either emphasize endurance, strength, and music-movement coordination (exercise intervention, EI) or stretching, toning and relaxation (exercise control, EC). This RCT will investigate the short and long-term effects of combined multi-domain training compared to cognitive training and physical training alone, on executive control and memory functions of healthy older adults, in comparison with the performance of an active control group. This trial is an ongoing project started in 2018. Trial registration: Clinicaltrials.gov ID: NCT03823183; https://register.clinicaltrials.gov/

Cognitive resources are distributed among the entire auditory landscape in auditory scene analysis.

Although attention has been shown to enhance neural representations of selected inputs, the fate of unselected background sounds is still debated. The goal of the current study was to understand how processing resources are distributed among attended and unattended sounds during auditory scene analysis. We used a three-stream paradigm with four acoustic features uniquely defining each sound stream (frequency, envelope shape, spatial location, tone quality). We manipulated task load by having participants perform a difficult auditory task and an easy movie-viewing task with the same set of sounds in separate conditions. The mismatch negativity (MMN) component of event-related brain potentials (ERPs) was measured to evaluate sound processing in both conditions. We found no effect of task demands on unattended sound processing: MMNs were elicited by unattended deviants during both low- and high-load task conditions. A key factor of this result was the use of unique tone feature combinations to distinguish each of the three sound streams, strengthening the segregation of streams. In the auditory task, the P3b component demonstrates a two-stage process of target evaluation. Thus, these results, in conjunction with results of previous studies, suggest that stimulus-driven factors that strengthen stream segregation can free up processing capacity for higher-level analyses. The results illustrate the interactive nature of top-down and stimulus-driven processes in stream formation, supporting a distributive theory of attention that balances the strength of the bottom-up input with perceptual goals in analyzing the auditory scene.

Use of Digital Stimulation in the Treatment of Phobias: Results Following EEG and Evoked Potential

To verify the usefulness of visual stimulation in CBT techniques or systematic desensitization and flooding, through the study of neurocognitive responses (ERPs) to specific and repetitive phobic or neutral stimuli, in patients with specific phobias. The study involved 2 groups, both composed of 20 subjects: an experimental group and a control group. Slideshows consist of randomized phobic images, whose characteristics are personalized for the specific phobia, and neutral images identical for all subjects. The ERPs recorded during visual stimulation were analyzed, distinguishing the potentials generated by phobic and neutral stimulations. The ERPs present typical waves (P1, P2, P3a, and P3b) that represent the cortical processing of the image. The study shows, in phobic subjects with specific phobic stimuli, an increase in P2 component amplitude due to greater activation of cortical networks by emotional response and the increase in amplitude of P3b component compared with the control group, probably in relation to looking for specific details of the phobic image. It is interesting to note that P3b component tends to regress during repetitive stimulation. The study showed that, through digital stimulation, phobic patients become accustomed to the presentation of phobic stimuli with an average decrease of 12–13% in P2 and an average reduction of 25% in N2. This result allows the hypothesis that this stimulation is useful to replace stimulation in vivo, or as a preparation for it. The variation of the potential evoked during the stimulation can help the therapist modulate the stimulation itself. The authors also propose to continue the development of this research also using the development of augmented reality (VR).

Task switching and bilingualism in young and older adults: A behavioral and electrophysiological investigation

The current study investigated behavioral and electrophysiological (event-related potential; ERP) differences associated with task switching in a sample of young and older monolingual and bilingual adults. ERPs associated with task preparation (switch and mixing positivity) and task execution processes (N2 and P3b) were investigated. Participants performed a cued letter-number task switching paradigm that included single task and mixed task blocks, while their electroencephalography was recorded. Behavioral results revealed smaller switch and mixing costs in bilinguals relative to monolinguals, in both young and older participants. There were no ERP differences in the effect size of the cue-locked mixing and switch positivities, nor the target-locked mixing and switch N2 and P3b components. However, overall larger target-locked N2 amplitudes were observed in bilinguals relative to monolinguals. In addition, bilingual older adults exhibited smaller P3b amplitudes than monolingual older adults. The smaller behavioral mixing and switch costs observed in bilinguals suggest that bilinguals exhibit superior sustained attention and faster task-set reconfiguration processes compared to monolinguals. The ERP measures provide evidence for differences in brain processes between monolinguals and bilinguals and a reliance on different processing strategies in bilingual compared to monolingual older adults.

Effects of acute aerobic and resistance exercise on executive function: An ERP study

ObjectivesThis study addressed the effects of acute, moderate-intensity aerobic and resistance exercise on the shifting aspect of cognition following a 30-min recovery period. It also explored the neuro-electrical activation that underlies the relationship between acute exercise and cognitive function through the examination of P3b and N1 components of event-related potentials. DesignA counterbalanced, repeated-measures experimental design. MethodsThirty-five volunteer young adults completed two experimental sessions (i.e., acute aerobic exercise (AE) and resistance exercise (RE), matched in terms of intensity, and one reading session (control). The AE entailed cycling at 60–70% of maximal heart rate reserve for 30min. In the RE session, participants performed seven exercises with two sets of 8–12 repetitions at 70% of 10-repetition maximum. Each participant's neuro-electrical activation was recorded 30min after each session while s/he completed the task-switching test. ResultsAfter the 30-min recovery period, both AE and RE elicited shorter response times in global switching (ηp2=0.24) and local switching (ηp2=0.16) were observed when compared to control. Additionally, larger P3b amplitudes (but not N1 amplitudes) were evident in global switching (ηp2=0.15) and local switching (ηp2=0.16), regardless of exercise modality. ConclusionsThe present findings suggest that acute exercise has positive effects on cognitive function. Exercise-induced alterations during the later stages of mental processing might result in superior performance. There were significant selective benefits in terms of brain function regardless of exercise modality.

A systematic review of physical activity and cardiorespiratory fitness on P3b

Given accumulating evidence indicating that acute and chronic physical activity and cardiorespiratory fitness are related to modulation of the P3b-ERP component, this systematic review provides an overview of the field across the last 30+ years and discusses future directions as the field continues to develop. A systematic review was conducted on studies of physical activity and cardiorespiratory fitness on P3b. PubMed, Web of Science, and Scopus were searched from database inception to March 28, 2018. Search results were limited to peer-reviewed and English-written studies investigating typically developed individuals. Seventy-two studies were selected, with 39 studies examining cross-sectional relationships between chronic physical activity (n=19) and cardiorespiratory fitness (n=20) with P3b, with 16 and 17 studies reporting associations of P3b with physical activity and cardiorespiratory fitness, respectively. Eight studies investigated the effects of chronic physical activity interventions, and all found effects on P3b. Eight studies investigating P3b during acute bouts of physical activity showed inconsistent results. Nineteen of 23 studies demonstrated acute modulation of P3b following exercise cessation. Conclusions drawn from this systematic review suggest that physical activity and cardiorespiratory fitness are associated with P3b modulation during cognitive control and attention tasks. Acute and chronic physical activity interventions modulate the P3b component, suggesting short- and long-term functional adaptations occurring in the brain to support cognitive processes. These summary findings suggest physical activity and cardiorespiratory fitness are beneficial to brain function and that P3b may serve as a biomarker of covert attentional processes to better understand the relationship of physical activity and cognition.

ERPs predict symptomatic distress and recovery in sub-acute mild traumatic brain injury

Mild traumatic brain injury (mTBI) can affect high-level executive functioning long after somatic symptoms resolve. We tested if simple EEG responses within an oddball paradigm could capture variance relevant to this clinical problem. The P3a and P3b components reflect bottom-up and top-down processes driving engagement with exogenous stimuli. Since these features are related to primitive decision abilities, abnormal amplitudes following mTBI may account for problems in the ability to exert executive control. Sub-acute (<2 weeks) mTBI participants (N = 38) and healthy controls (N = 24) were assessed at an initial session as well as a two-month follow-up (sessions 1 and 2). We contrasted the initial assessment to a comparison group of participants with chronic symptomatology following brain injury (N = 23). There were no group differences in P3a or P3b amplitudes. Yet in the sub-acute mTBI group, higher symptomatology on the Frontal Systems Behavior scale (FrSBe), a questionnaire validated as measuring symptomatic distress related to frontal lobe injury, correlated with lower P3a in session 1. This relationship was replicated in session 2. These findings were distinct from chronic TBI participants, who instead expressed a relationship between increased FrSBe symptoms and a lower P3b component. In the sub-acute group, P3b amplitudes in the first session correlated with the degree of symptom change between sessions 1 and 2, above and beyond demographic predictors. Controls did not show any relationship between FrSBe symptoms and P3a or P3b. These findings identify symptom-specific alterations in neural systems that vary along the time course of post-concussive symptomatology.

Being right matters: Model-compliant events in predictive processing.

While prediction errors (PE) have been established to drive learning through adaptation of internal models, the role of model-compliant events in predictive processing is less clear. Checkpoints (CP) were recently introduced as points in time where expected sensory input resolved ambiguity regarding the validity of the internal model. Conceivably, these events serve as on-line reference points for model evaluation, particularly in uncertain contexts. Evidence from fMRI has shown functional similarities of CP and PE to be independent of event-related surprise, raising the important question of how these event classes relate to one another. Consequently, the aim of the present study was to characterise the functional relationship of checkpoints and prediction errors in a serial pattern detection task using electroencephalography (EEG). Specifically, we first hypothesised a joint P3b component of both event classes to index recourse to the internal model (compared to non-informative standards, STD). Second, we assumed the mismatch signal of PE to be reflected in an N400 component when compared to CP. Event-related findings supported these hypotheses. We suggest that while model adaptation is instigated by prediction errors, checkpoints are similarly used for model evaluation. Intriguingly, behavioural subgroup analyses showed that the exploitation of potentially informative reference points may depend on initial cue learning: Strict reliance on cue-based predictions may result in less attentive processing of these reference points, thus impeding upregulation of response gain that would prompt flexible model adaptation. Overall, present results highlight the role of checkpoints as model-compliant, informative reference points and stimulate important research questions about their processing as function of learning und uncertainty.

Childhood leukemia survivors exhibit deficiencies in sensory and cognitive processes, as reflected by event-related brain potentials after completion of curative chemotherapy: A preliminary investigation

ABSTRACTObjective: The purpose of this study was to characterize post-chemotherapy sensory, memory, and attention abilities in childhood survivors of acute lymphoblastic leukemia (ALL) to better understand how treatment affects cognitive functioning.Methods: Eight ALL survivors and eight age-matched, healthy children between the ages of 5-11 years participated in the study. Among the ALL survivors, a median of 63 days (range 22-267 days) elapsed between completion of chemotherapy and this assessment. Sounds were presented in an oddball paradigm while recording the electroencephalogram in separate conditions of passive listening and active task performance. To assess different domains of cognition, we measured event-related brain potentials (ERPs) reflecting sensory processing (P1 component), working memory (mismatch negativity [MMN] component), attentional orienting (P3a), and target detection (P3b component) in response to the sounds. We also measured sound discrimination and response speed performance.Results: Relative to control subjects, ALL survivors had poorer performance on auditory tasks, as well as decreased amplitude of the P1, MMN, P3a, and P3b components. ALL survivors also did not exhibit the amplitude gain typically observed in the sensory P1 component when attending to the sound input compared to when passively listening.Conclusions: Atypical responses were observed in brain processes associated with sensory discrimination, auditory working memory, and attentional control in pediatric ALL survivors indicating deficiencies in all cognitive domains compared to age-matched controls.Significance: ERPs differentiated aspects of cognitive functioning, which may provide a useful tool for assessing recovery and risk of post-chemotherapy cognitive deficiencies in young children. The decreased MMN amplitude in ALL survivors may indicate (N-methyl D-aspartate) NMDA dysfunction induced by methotrexate, and thus provides a potential therapeutic target for chemotherapy-associated cognitive impairments.

Role of the insula in top-down processing: an intracranial EEG study using a visual oddball detection paradigm.

Functional neuroimaging studies suggest that the insular cortex-and more especially the anterior insula (aI)-is involved in attentional processes and plays a crucial role in the "salience network". However, its specific role in attentional processing remains unclear, which is partly attributable to the low temporal resolution of non-invasive neuroimaging techniques. This study aims to examine the spatio-temporal dynamics of visual target processing using intracranial EEG recorded directly from the insula. Eight epileptic patients (four women, age 18-44years) completed a three-stimulus visual oddball task during the extraoperative invasive intracranial EEG (iEEG) monitoring of their drug-resistant seizures. Depth electrodes were implanted in ten insular lobes (5 left and 5 right) and provided a total of 59 recording contacts in the insula. Event-related potentials (ERPs) and high-gamma-band responses (GBRs) were processed offline. Permutation analyses were performed to compare ERP signals across conditions during the P300 (225-400) interval, and modulations of GBRs (70-150Hz) were computed for separate 100ms time windows (from 0 to 1000ms post-stimulus) and compared across conditions using non-parametric Wilcoxon test. Target stimuli were associated with a P300 (250-338ms) component for 39% of contacts implanted in the aI, most probably reflecting voluntary attentional processing. Amplitude was significantly greater for target than for standard stimuli for all of these contacts, and was greater than for novel stimuli for 72%. In the posterior insula (pI), 16% of contacts showed preferential responses to target stimulus in the P300 interval. Increased GBRs in response to targets were observed in 53% of aI contacts (from ≈ 200 to 300ms) and in 43% of pI contacts (from ≈ 400 to 500ms). This study is the first to characterize the spatio-temporal dynamics of visual target processing in the insula using iEEG. Results suggest that visual targets elicit a P300 in the aI which corresponds in latency to the P3b component, suggesting that this region is involved in top-down processing of task-relevant information. GBRs to visual targets occur earlier in the aI than in the pI, further characterizing their respective roles in voluntary attentional processing.