P300 Amplitude Research Articles

Lower cognitive reserve is related to worse working memory performance in older adults after mTBI. An ERP study

ABSTRACT Objective Older adults (OA) after mild traumatic brain injury (mTBI) have a high risk of developing persistent post-injury cognitive impairments. Lower pre-morbid cognitive reserve (CR) is increasingly investigated as a risk factor for cognitive dysfunction in OA. However, how CR protects against effects of mTBI at the brain level remains largely understudied. Methods We examined 22 OA who sustained mTBI (mean 67.69 years, SD 5.11) in the sub-acute phase and 15 age- and CR-matched healthy OA (mean 68 years, SD 5.55) performing a three-level visual N-back task using electroencephalography. We calculated inverse efficiency scores of performance from accuracy and reaction times. Event-related potentials served as neurocognitive correlates of attentional (P2) and working memory (P3) processing. Results Overall, mTBI OA performed worse than healthy OA (p = 0.031). Lower CR generally decreased performance (p < 0.001). Furthermore, with increasing task difficulty, task performance was more affected by CR (p = 0.004). At the brain level, P2 amplitude was lower in mTBI OA than in healthy OA (p = 0.05). There was no clear effect of CR on P2 or P3 measures. Conclusion As mTBI OA with lower CR performed worse on a working-memory task, lower CR may be a risk factor for worse recovery after mTBI in this group.

Investigation of fabric tactile perception using the event-related potential method

The mechanism of the neuro-electrophysiological response of the human brain to skin tactile stimulation has always been an important research topic in the field of comfort perception of textile materials. In order to explore the characteristic neural potential components induced by various fabric tactile stimulation and their influence rules, event-related potential technology with ultra-high time resolution was introduced to monitor the somatosensory brain region under tactile stimulation of fabrics with different tactile properties, and the signal changes of related potentials were extracted and analyzed. The results showed that the amplitudes of N100 increased with the stiffness of the fabric, the amplitudes of P200 decreased with the smoothness of the fabric, and the amplitudes of P300 decreased with the smoothness and softness of the fabric. These results indicated that N100, P200, and P300 potentials could be used as neurophysiological response indexes of brain neurons to distinguish the subtle differences in fabric tactile properties. This finding not only laid a scientific theoretical basis for the brain perception mechanism of fabric tactile properties, but also provided a possibility for further quantification characterization of textile comfort perception.

Differences in attentional function between experienced mindfulness meditators and non-meditators.

Attentional enhancement has often been identified as the central cognitive mechanism underlying the benefits of mindfulness meditation. However, the extent to which this enhancement is observable in the neural processes underlying long-term meditation is unclear. This current study aimed to examine differences in attentional performance between meditators and controls (non-meditators) using a visual oddball task with concurrent electroencephalography (EEG) recordings. Thirty-four participants were recruited, including 16 meditators and 18 healthy controls, who were non-meditators. The participants completed a visual oddball task, using visual stimuli, and EEG recording. Self-reports revealed that meditators had higher mindful attention scores than did the control group. The behavioral results showed that the meditators demonstrated faster reaction times than the non-meditators did. Neural findings indicated a higher P2 amplitude in the meditators than in the controls. The meditators demonstrated a significantly higher P3 in the target trials than in the distractor trials, which was not observed in the controls. Additionally, the time-frequency analysis demonstrated that the delta and theta powers in the meditators were significantly higher than those in the controls. The study suggests the meditators exhibited greater attentional performance than the controls did, as revealed by EEG and behavioral measures. This study extends previous research on the effects of mindfulness meditation on attention and adds to our understanding of the effects of long-term mindfulness meditation.

The Impact of Age-Related Hearing Loss on Working Memory among Older Individuals: An Event-Related Potential Study

Introduction: Age-related hearing loss (ARHL) may affect working memory (WM), which impacts problem-solving, decision-making, language comprehension, and learning. Limited research exists on how ARHL affects WM using N-back tasks, but studying this is crucial for understanding neural markers and associated cognitive processes. Our study explores the impact of ARHL on WM using behavioral and electrophysiological measures and how it correlates with speech-in-noise scores in older individuals with ARHL. Method: The study involved two groups, each with 20 participants aged 60–80. Group 1 had individuals with mild to moderate sensorineural hearing loss, while Group 2 had age- and education-matched controls with normal or near-normal hearing. Participants underwent audiological assessments and completed cognitive tests, including simple reaction time and N-back tests. During the performance of cognitive tasks, a simultaneous electroencephalography was recorded. Data analysis included behavioral and event-related potentials, source estimation, and functional connectivity analysis. Results: The study revealed significantly poor accuracy, longer reaction time, and smaller P300 amplitude among individuals with ARHL, even after controlling for general slowing. Individuals with ARHL experience compromised neural activity, particularly in the temporal and parietal regions, which are vital for cognition and WM. Furthermore, individuals with ARHL exhibited poor communication between the superior temporal gyrus and insulae regions among the brain regions mediating WM during the 1-back task. Also, the study found a strong correlation between hearing measures and WM outcomes. Conclusion: The study findings suggest that individuals with ARHL have impaired WM compared to those with normal hearing. This indicates a potential link between ARHL and cognitive decline, which could significantly affect daily life and quality of life. The widely used WM test with simultaneous EEG recording and source estimation analysis would further validate the usefulness of the study in assessing WM in this population.

Mandarin-Speaking Amusics' Online Recognition of Tone and Intonation.

Congenital amusia is a neurogenetic disorder of musical pitch processing. Its linguistic consequences have been examined separately for speech intonations and lexical tones. However, in a tonal language such as Chinese, the processing of intonations and lexical tones interacts with each other during online speech perception. Whether and how the musical pitch disorder might affect linguistic pitch processing during online speech perception remains unknown. We investigated this question with intonation (question vs. statement) and lexical tone (rising Tone 2 vs. falling Tone 4) identification tasks using the same set of sentences, comparing behavioral and event-related potential measurements between Mandarin-speaking amusics and matched controls. We specifically focused on the amusics without behavioral lexical tone deficits (the majority, i.e., pure amusics). Results showed that, despite relative to normal performance when tested in word lexical tone test, pure amusics demonstrated inferior recognition than controls during sentence tone and intonation identification. Compared to controls, pure amusics had larger N400 amplitudes in question stimuli during tone task and smaller P600 amplitudes in intonation task. These data indicate that musical pitch disorder affects both tone and intonation processing during sentence processing even for pure amusics, whose lexical tone processing was intact when tested with words.

Unpredictable threat increases early event-related potential amplitudes and cardiac acceleration: A brain-heart coupling study.

In the face of unpredictable threat, rapid processing of external events and behavioral mobilization through early psychophysiological responses are crucial for survival. While unpredictable threat generally enhances early processing, it would seem adaptive to particularly increase sensitivity for unexpected events as they may signal danger. To examine this possibility, n = 77 participants performed an auditory oddball paradigm and received unpredictable shocks in threat but not in safe contexts while a stream of frequent (standard) and infrequent (deviant) tones was presented. We assessed event-related potentials (ERP), heart period (HP), and time-lagged within-subject correlations of single-trial EEG and HP (cardio-EEG covariance tracing, CECT) time-locked to the tones. N1 and P2 ERP amplitudes were generally enhanced under threat. The P3 amplitude was enhanced to deviants versus standards and this effect was reduced in the threat condition. Regarding HP, both threat versus safe and unexpected versus expected tones led to stronger cardiac acceleration, suggesting separate effects of threat and stimulus expectancy on HP. Finally, CECTs revealed two correlation clusters, indicating that single-trial EEG magnitudes in the N1/P2 and P3 time-windows predicted subsequent cardiac acceleration. The current results show that an unpredictable threat context enhances N1 and P2 amplitudes and cardiac acceleration to benign auditory stimuli. They further suggest separable cortical correlates of different effects on cardiac activity: an early N1/P2 correlate associated with threat-effects on HP and a later P3 correlate associated with expectedness-effects. Finally, the results indicate that unpredictable threat attenuates rather than enhances the processing of unexpected benign events during the P3 latency.

Evaluation of Photodynamic Therapy-combined Intravitreal Bevacizumab in Age-related Macular Degeneration

Aim: It was aimed to compare treatment results of photodynamic therapy (PDT) and PDT-combined intravitreal bevacizumab injection (PDT+IVB) in patients with age-related macular degeneration (AMD). Material and Methods: 63 eyes of 55 patients with neovascular AMD were included. Group 1 consisted of 40 eyes of 35, group 2 consisted of 23 eyes of 20 patients. Visual acuity (VA), intraocular pressure measurement and fundus examination were performed. Pattern Electroretinography P50 amplitude and edema map values (EMV) were measured with Heidelberg Retina Tomograph (HRTII). Results: VA increased in 14, remained unchanged in 17, decreased in 9 eyes in Group 1 (PDT). The PERG P50 amplitudes were compared with values of pre-treatment, and found increased as 10.6%, 11.98%, and 8.46% and HRTII EMV were 5.86%, 4.88%, and 11.22% at 1st, 3rd, and 6th months, respectively. In Group 2 (PDT+IVB), VA improved in 9, remained unchanged in 8, decreased in 6 eyes. PERG P50 amplitudes were decreased as 10.15%, 5.8%, and 0.1% and HRTII EMV were decreased as 13.07%, 12.17%, and 14.87% at 1st, 3rd, and 6th months, respectively. Conclusion: Verteporfin and PDT are effective and safe methods that preserve VA in subfoveal choroidal neovascular membranes due to neovascular AMD.

P3b correlates of inspection time

Both P3b and the inspection time (IT) are related with intelligence, yet the P3b correlates of IT are not well understood. This event-related potential study addressed this question by asking participants (N = 28) to perform an IT task. There were three IT conditions with different levels of discriminative stimulus duration, i.e., 33 ms, 67 ms, and 100 ms, and a control condition with no target presentation (0 ms condition). We also measured participants' processing speed with four Elementary Cognitive Tests (ECTs), including a Simple Reaction Time task (SRT), two Choice Reaction Time tasks (CRTs), and a Pattern Discrimination task (PD). Results revealed that an increase in P3b latency with longer duration of the discriminative stimulus. Moreover, the P3b latency was negatively correlated with the accuracy of the IT task in the 33 ms condition, but not evident in the 67 and 100 ms conditions. Furthermore, the P3b latency of the 33 ms condition was positively correlated with the RT of the SRT, but not related with the RTs of CRTs or PD. A significant main effect of duration on the amplitude of P1 was also found. We conclude that the present study provides the neurophysiological correlates of the IT task, and those who are able to accurately perceive and process very briefly presented stimuli have a higher speed of information process, reflected by the P3b latency, yet this relationship is more obvious in the most difficult condition. Combined, our results suggest that P3b is related with the closure of a perceptual epoch to form the neural representation of a stimulus, in support of the “context closure” hypothesis.

Accelerating P300-based neurofeedback training for attention enhancement using iterative learning control: a randomised controlled trial

Objective. Neurofeedback (NFB) training through brain–computer interfacing has demonstrated efficacy in treating neurological deficits and diseases, and enhancing cognitive abilities in healthy individuals. It was previously shown that event-related potential (ERP)-based NFB training using a P300 speller can improve attention in healthy adults by incrementally increasing the difficulty of the spelling task. This study aims to assess the impact of task difficulty adaptation on ERP-based attention training in healthy adults. To achieve this, we introduce a novel adaptation employing iterative learning control (ILC) and compare it against an existing method and a control group with random task difficulty variation. Approach. The study involved 45 healthy participants in a single-blind, three-arm randomised controlled trial. Each group underwent one NFB training session, using different methods to adapt task difficulty in a P300 spelling task: two groups with personalised difficulty adjustments (our proposed ILC and an existing approach) and one group with random difficulty. Cognitive performance was evaluated before and after the training session using a visual spatial attention task and we gathered participant feedback through questionnaires. Main results. All groups demonstrated a significant performance improvement in the spatial attention task post-training, with an average increase of 12.63%. Notably, the group using the proposed iterative learning controller achieved a 22% increase in P300 amplitude during training and a 17% reduction in post-training alpha power, all while significantly accelerating the training process compared to other groups. Significance. Our results suggest that ERP-based NFB training using a P300 speller effectively enhances attention in healthy adults, with significant improvements observed after a single session. Personalised task difficulty adaptation using ILC not only accelerates the training but also enhances ERPs during the training. Accelerating NFB training, while maintaining its effectiveness, is vital for its acceptability by both end-users and clinicians.

Context Modulates Perceived Fairness in Altruistic Punishment: Neural Signatures from ERPs and EEG Oscillations.

Social norms and altruistic punitive behaviours are both based on the integration of information from multiple contexts. Individual behavioural performance can be altered by loss and gain contexts, which produce different mental states and subjective perceptions. In this study, we used event-related potential and time-frequency techniques to examine performance on a third-party punishment task and to explore the neural mechanisms underlying context-dependent differences in punishment decisions. The results indicated that individuals were more likely to reject unfairness in the context of loss (vs. gain) and to increase punishment as unfairness increased. In contrast, fairness appeared to cause an early increase in cognitive control signal enhancement, as indicated by the P2 amplitude and theta oscillations, and a later increase in emotional and motivational salience during decision-making in gain vs. loss contexts, as indicated by the medial frontal negativity and beta oscillations. In summary, individuals were more willing to sanction violations of social norms in the loss context than in the gain context and rejecting unfair losses induced more equity-related cognitive conflict than accepting unfair gains, highlighting the importance of context (i.e., gain vs. loss) in equity-related social decision-making processes.

Distinct and common mechanisms of cross-model semantic conflict and response conflict in an auditory relevant task.

The mechanisms of semantic conflict and response conflict in the Stroop task have mainly been investigated in the visual modality. However, the understanding of these mechanisms in cross-modal modalities remains limited. In this electroencephalography (EEG) study, an audiovisual 2-1 mapping Stroop task was utilized to investigate whether distinct and/or common neural mechanisms underlie cross-modal semantic conflict and response conflict. The response time data showed significant effects on both cross-modal semantic and response conflicts. Interestingly, the magnitude of semantic conflict was found to be smaller in the fast response time bins than in the slow response time bins, whereas no such difference was observed for response conflict. The EEG data demonstrated that cross-modal semantic conflict specifically increased the N450 amplitude. However, cross-modal response conflict specifically enhanced theta band power and theta phase synchronization between the medial frontal cortex (MFC) and lateral prefrontal electrodes as well as between the MFC and motor electrodes. In addition, both cross-modal semantic conflict and response conflict led to a decrease in P3 amplitude. Taken together, these findings provide cross-modal evidence for domain-specific mechanism in conflict detection and suggest both domain-specific and domain-general mechanisms exist in conflict resolution.

Attentional deficits in fibromyalgia: an ERP study with the oddball dual task and emotional stroop task

The present study investigated the neural correlates of attentional deficits in fibromyalgia through an Oddball Dual Task and an Emotional Stroop Task, both performed during EEG recordings. Thirty female participants were recruited, being divided into two groups: a group of patients with fibromyalgia (FM, n = 15, Mage = 51.87, SDage = 7.12) and a healthy control group (HC, n = 15, Mage = 46.13, SDage = 8.41). In the Emotional Stroop Task, the behavioural results showed that patients with FM had less hits and longer times reactions than healthy controls. These results were consistent with those obtained with our Event-related Potential (ERP) methodology, which evidenced that patients with FM had higher frontal latencies in the P200 time-window compared to healthy controls. Regarding the Oddball Dual Task, we found that patients with FM had lower P300 amplitudes than healthy participants. Moreover, we found that rare stimuli elicited higher P300 amplitudes than frequent stimuli for healthy controls, but this comparison was non-significant for patients with FM. Taken together, our results suggest that fibromyalgia may be associated to a reduced processing speed, along to reduced neural resources to process stimuli, mainly in distinguishing relevant (rare) and irrelevant (frequent) stimuli according to the goals of the task. Altogether, our results seem to support the hypothesis of generalized attentional deficits in FM.

Working memory load impairs tacit coordination but not inter-brain EEG synchronization.

Coordinating actions with others is thought to require Theory of Mind (ToM): the ability to take perspective by attributing underlying intentions and beliefs to observed behavior. However, researchers have yet to establish a causal role for specific cognitive processes in coordinated action. Since working memory load impairs ToM in single-participant paradigms, we tested whether load manipulation affects two-person coordination. We used EEG to measure P3, an assessment of working memory encoding, as well as inter-brain synchronization (IBS), which is thought to capture mutual adjustment of behavior and mental states during coordinated action. In a computerized coordination task, dyads were presented with novel abstract images and tried selecting the same image, with selections shown at the end of each trial. High working memory load was implemented by a concurrent n-back task. Compared with a low-load control condition, high load significantly diminished coordination performance and P3 amplitude. A significant relationship between P3 and performance was found. Load did not affect IBS, nor did IBS affect performance. These findings suggest a causal role for working memory in two-person coordination, adding to a growing body of evidence challenging earlier claims that social alignment is domain-specific and does not require executive control in adults.

A sleepless night disrupts the resolution of emotional conflicts: Behavioural and neural evidence.

The present study aims to investigate the influence of 24-hr sleep deprivation on implicit emotion regulation using the emotional conflict task. Twenty-five healthy young adults completed a repeated-measures study protocol involving a night of at-home normal sleep control and a night of in-laboratory sleep deprivation. Prior to the experimental session, all participants wore an actigraph watch and completed the sleep diary. Following each condition, participants performed an emotional conflict task with electroencephalographic recordings. Emotional faces (fearful or happy) overlaid with words ("fear" or "happy") were used as stimuli creating congruent or incongruent trials, and participants were instructed to indicate whether the facial expression was happy or fearful. We measured the accuracy and reaction time on the emotional conflict task, as well as the mean amplitude of the P300 component of the event-related potential at CPz. At the behavioural level, sleep-deprived participants showed reduced alertness with overall longer reaction times and higher error rates. In addition, participants in the sleep deprivation condition made more errors when the current trial followed congruent trials compared with when it followed incongruent trials. At the neural level, P300 amplitude evoked under the sleep-deprived condition was significantly more positive compared with the normal sleep condition, and this effect interacted with previous-trial and current-trial congruency conditions, suggesting that participants used more attentional resources to resolve emotional conflicts when sleep deprived. Our study provided pioneering data demonstrating that sleep deprivation may impair the regulation of emotional processing in the absence of explicit instruction among emerging adults.

A longitudinal study on the impact of high-altitude hypoxia on perceptual processes.

This study aimed to explore the neural mechanisms underlying high-altitude (HA) adaptation and deadaptation in perceptual processes in lowlanders. Eighteen healthy lowlanders were administered a facial S1-S2 matching task that included incomplete face (S1) and complete face (S2) photographs combined with ERP technology. Participants were tested at four time points: shortly before they departed the HA (Test 1), twenty-five days after entering the HA (Test 2), and one week (Test 3) and one month (Test 4) after returning to the lowlands. Compared with those at sea level (SL), shorter reaction times (RTs), shorter latencies of P1 and N170, and larger amplitudes of complete face N170 were found in HAs. After returning to SL, compared with that of HA, the amplitude of the incomplete face P1 was smaller after one week, and the complete face was smaller after one month. The right hemisphere N170 amplitude was greater after entering HA and one week after returning to SL than at baseline, but it returned to baseline after one month. Taken together, the current findings suggest that HA adaptation increases visual cortex excitation to accelerate perceptual processing. More mental resources are recruited during the configural encoding stage of complete faces after HA exposure. The perceptual processes affected by HA exposure are reversible after returning to SL, but the low-level processing stage differs between incomplete and complete faces due to neural compensation mechanisms. The configural encoding stage in the right hemisphere is affected by HA exposure and requires more than one week but less than one month to recover to baseline.

Neurocognitive mechanisms of mental imagery-based disgust learning

Disgust imagery represents a potential pathological mechanism for disgust-related disorders. However, it remains controversial as to whether disgust can be conditioned with disgust-evoking mental imagery serving as the unconditioned stimulus (US). Therefore, we examined this using a conditioned learning paradigm in combination with event-related potential (ERP) analysis in 35 healthy college students. The results indicated that the initial neutral face (conditioned stimulus, CS+) became more disgust-evoking, unpleasant, and arousing after pairing with disgust-evoking imagery (disgust CS+), compared to pairing with neutral (neutral CS+) and no (CS−) imagery. Moreover, we observed that mental imagery-based disgust conditioning was resistant to extinction. While the disgust CS + evoked larger P3 and late positive potential amplitudes than CS− during acquisition, no significant differences were found between disgust CS+ and neutral CS+, indicating a dissociation between self-reported and neurophysiological responses. Future studies may additionally acquire facial EMG as an implicit index of conditioned disgust. This study provides the first neurobiological evidence that associative disgust learning can occur without aversive physical stimuli, with implications for understanding how disgust-related disorders may manifest or deteriorate without external perceptual aversive experiences, such as in obsessive-compulsive disorder (OCD).

Long-term findings on working memory neural dynamics in healthcare workers after mild COVID-19

ObjectiveUnderstanding the long-term impact of Coronavirus Disease 2019 (COVID-19) on cognitive function, even in mild cases, is critical to the well-being of individuals, especially for healthcare workers who are at increased risk of exposure to the virus. To the best of our knowledge, the electrophysiological activity underlying cognitive functioning has not yet been explored. MethodsSeventy-seven healthcare workers took part in the study (43 with mild infection about one year before the study and 34 uninfected). To assess cognitive status, event-related potentials (ERPs) and behavioural responses were recorded while participants performed a working memory task. ResultsCOVID-19 participants exhibited a distinct neural pattern with lower parieto-occipital N1 amplitudes and higher frontal P2 amplitudes as compared to non-infected healthcare workers. We found no behavioural differences (reaction times and error rates) in working memory functioning between groups. ConclusionsThis neural pattern suggests the presence of a decrement of processing resources linked to the encoding of sensory information (N1), followed by the enhanced of the P2 response which could be interpreted as the activation of compensation mechanism in COVID-19 participants. SignificanceThe current findings point out that ERPs could serve as valuable neural indices for detecting distinctive patterns in working memory functioning of COVID-19 participants, even in mild cases. However, further research is required to precisely ascertain the long-term cognitive effects of COVID-19 beyond one-year post-infection.

Impact of weight reduction on structural and functional parameters of the optic nerve in idiopathic intracranial hypertension.

To evaluate the effect of weight reduction on the structural and functional parameters of the optic nerve in established cases of papilledema in Idiopathic Intracranial Hypertension (IIH). A prospective observational study in early and established cases of papilledema in IIH presenting from December 2019 to February 2021. Functional parameters (visual acuity, contrast sensitivity, mean deviation, VER), structural parameters (RNFL, GCL-IPL, and optic disc height), and clinical grading of papilledema were measured at baseline and every 6 weeks for 6 months. All patients underwent medical (oral acetazolamide) and diet therapy. Mean body mass index (BMI) at presentation was 26.32 ± 3.52 kg/m² and the mean change in BMI over 6 months was 1.27 ± 0.50 kg/m². 67% of eyes had papilledema of grades 2-3 at the presentation. At the end of 6 months, 75% of eyes had grade 1 papilledema while 13% showed complete resolution. A reduction of 5.32 ± 3.58 in mean deviation (r = 0.316; p-value 0.01) and gain in VER P100 amplitude of 4.2 ± 2.7 µV (r = 0.40; p-value 0.003) were noted over 6 months with reduction in BMI over 6 months. A statistically significant reduction in optic disc height (ODH) was noticed with BMI reduction over 6 months (p = 0.0007; r = 0.45).A reduction of 1.72 ± 0.90 kg/m² (equivalent to 6.53% weight loss) in BMI was associated with a four-grade change in clinical grading of papilledema. Reduction in BMI had a significant impact on both structural and functional parameters of the optic nerve in IIH. The involvement of a well-certified dietician should be an integral part of treatment in IIH.

True pattern-reversal LED stimulator and its comparison to LCD and CRT displays: visual evoked potential study

A rapid checkerboard pattern change is used to elicit pattern-reversal visual evoked potentials (PR VEPs). CRT or LCD monitors do not allow immediate reversal of the entire pattern. The study aimed to construct a new stimulator whose characteristics approximate an instantaneous reversal and verify whether the improvement is reflected in PR VEPs. A new stimulator using a matrix of 12 × 48 independent white square LEDs was designed and compared with LCDs and CRTs. The effect on the PR VEP peak times and amplitudes of N70, P100, and P140 waves was evaluated in ten subjects. The LED stimulator showed significantly better performance in the rate of change of illuminance, change of pattern, luminance settling and stability. The PR VEP amplitudes of N75, P100, and N140 did not show significant differences. The sum of interpeak amplitudes was significantly larger for the LCD than for the other monitors. The peak times of the waves evoked by the LED were shorter than those evoked by the LCD and CRT for the N75 wave and a check size of 30´. LED stimulators are a better alternative to CRTs for PR VEPs than current LCDs. LEDs also seem to be better than CRTs, but further research is necessary to obtain significant results.

Transcranial magnetic stimulation effects support an oscillatory model of ERP genesis

Whether prestimulus oscillatory brain activity contributes to the generation of post-stimulus-evoked neural responses has long been debated, but findings remain inconclusive. We first investigated the hypothesized relationship via EEG recordings during a perceptual task with this correlational evidence causally probed subsequently by means of online rhythmic transcranial magnetic stimulation. Both approaches revealed a close link between prestimulus individual alpha frequency (IAF) and P1 latency, with faster IAF being related to shorter latencies, best explained via phase-reset mechanisms. Moreover, prestimulus alpha amplitude predicted P3 size, best explained via additive (correlational and causal evidence) and baseline shift mechanisms (correlational evidence), each with distinct prestimulus alpha contributors. Finally, in terms of performance, faster prestimulus IAF and shorter P1 latencies were both associated with higher task accuracy, while lower prestimulus alpha amplitudes and higher P3 amplitudes were associated with higher confidence ratings. Our results are in favor of the oscillatory model of ERP genesis and modulation, shedding new light on the mechanistic relationship between prestimulus oscillations and functionally relevant evoked components.