Effects of auditory stimulus intensity and hearing threshold on the relationship among P300, age, and cognitive function

The P300 Auditory Evoked Potential in Cochlear Implant Users: A Scoping Review

Introduction  The P300 auditory evoked potential is a long-latency cortical potential evoked with auditory stimulation, which provides information on neural mechanisms underlying the central auditory processing. Objectives  To identify and gather scientific evidence regarding the P300 in adult cochlear implant (CI) users. Data Synthesis  A total of 87 articles, 20 of which were selected for this study, were identified and exported to the Rayyan search software. Those 20 articles did not propose a homogeneous methodology, which made comparison more difficult. Most articles (60%) in this review compare CI users with typical hearing people, showing prolonged P300 latency in CI users. Among the studies, 35% show that CI users present a smaller P300 amplitude. Another variable is the influence of the kind of stimulus used to elicit P300, which was prolonged in 30% of the studies that used pure tone stimuli, 10% of the studies that used pure tone and speech stimuli, and 60% of the studies that used speech stimuli. Conclusion  This review has contributed with evidence that shows the importance of applying a controlled P300 protocol to diagnose and monitor CI users. Regardless of the stimuli used to elicit P300, we noticed a pattern in the increase in latency and decrease in amplitude in CI users. The user's experience with the CI speech processor over time and the speech test results seem to be related to the P300 latency and amplitude measurements.

Auditory evoked response to an oddball paradigm in children wearing cochlear implants

OBJECTIVE

Although children with cochlear implants (CI) achieve remarkable success with their device, considerable variability remains in individual outcomes. Here, we explored whether auditory evoked potentials recorded during an oddball paradigm could provide useful markers of auditory processing in this pediatric population.

METHODS

High-density electroencephalography (EEG) was recorded in 75 children listening to standard and odd noise stimuli: 25 had normal hearing (NH) and 50 wore a CI, divided between high language (HL) and low language (LL) abilities. Three metrics were extracted: the first negative and second positive components of the standard waveform (N1-P2 complex) close to the vertex, the mismatch negativity (MMN) around Fz and the late positive component (P3) around Pz of the difference waveform.

RESULTS

While children with CIs generally exhibited a well-formed N1-P2 complex, those with language delays typically lacked reliable MMN and P3 components. But many children with CIs with age-appropriate skills showed MMN and P3 responses similar to those of NH children. Moreover, larger and earlier P3 (but not MMN) was linked to better literacy skills.

CONCLUSIONS

Auditory evoked responses differentiated children with CIs based on their good or poor skills with language and literacy.

SIGNIFICANCE

This short paradigm could eventually serve as a clinical tool for tracking the developmental outcomes of implanted children.

Disrupted gut microbiota aggravates working memory dysfunction induced by high-altitude exposure in mice

Background

The widely accepted microbiome-gut-brain axis (MGBA) hypothesis may be essential for explaining the impact of high-altitude exposure on the human body, especially brain function. However, studies on this topic are limited, and the underlying mechanism remains unclear. Therefore, this study aimed to determine whether high-altitude-induced working memory dysfunction could be exacerbated with gut microbiota disruption.

Methods and results

C57BL/6 mice were randomly divided into three groups: control, high-altitude exposed (HAE), and high-altitude exposed with antibiotic treatment (HAE-A). The HAE and HAE-A groups were exposed to a low-pressure oxygen chamber (60-65 kPa) simulating the altitude of 3,500-4,000 m for 14 days, The air pressure level for the control group was maintained at 94.5 kPa. Antibiotic water (mixed with 0.2 g/L of ciprofloxacin and 1 g/L of metronidazole) was provided to the HAE-A group. Based on the results of the novel object test and P300 in the oddball behavioral paradigm training test, working memory dysfunction was aggravated by antibiotic treatment. We determined the antioxidant capacity in the prefrontal cortex and found a significant negative influence (p < 0.05) of disturbed gut microbiota on the total antioxidant capacity (T-AOC) and malondialdehyde (MDA) content, as well as the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). The same trend was also observed in the apoptosis-related functional protein content and mRNA expression levels in the prefrontal cortex, especially the levels of bcl-2, Bax, and caspase-3. The high-altitude environment and antibiotic treatment substantially affected the richness and diversity of the colonic microbiota and reorganized the composition and structure of the microbial community. S24-7, Lachnospiraceae, and Lactobacillaceae were the three microbial taxa with the most pronounced differences under the stimulation by external factors in this study. In addition, correlation analysis between colonic microbiota and cognitive function in mice demonstrated that Helicobacteraceae may be closely related to behavioral results.

Conclusion

Disrupted gut microbiota could aggravate working memory dysfunction induced by high-altitude exposure in mice, indicating the existence of a link between high-altitude exposure and MGBA.

Documentation of Peripheral Auditory Function in Studies of the Auditory P300 Response

Abstract. A critical review was conducted to examine whether the peripheral hearing status of participants with neurological and psychological disorders was documented in published clinical studies of the auditory P300 response. Literature searches were conducted with three databases: PubMed, PsycINFO, and Scopus. Studies of participants with seven neurological or psychological disorders were included in the study. Each disorder was coupled with the main search phrase in separate searches on each database. Of the total 102 papers which met the inclusion criteria, the majority (64%) did not describe the peripheral hearing sensitivity of participants. In this review with studies that included participants at risk for hearing impairment, particularly age-related hearing loss, only a single publication adequately described formal hearing evaluation. Peripheral hearing status is rarely defined in studies of the P300 response. The inclusion of participants with a hearing loss likely affects the validity of findings for these studies. We recommend formal hearing assessment prior to inclusion of participants in studies of the auditory P300 response. The findings of this study may increase the awareness among researchers outside the field of audiology of the effects of peripheral hearing loss on the auditory P300.

A Multidimensional Investigation of Sensory Processing in Autism: Parent- and Self-Report Questionnaires, Psychophysical Thresholds, and Event-Related Potentials in the Auditory and Somatosensory Modalities

Background

Reconciling results obtained using different types of sensory measures is a challenge for autism sensory research. The present study used questionnaire, psychophysical, and neurophysiological measures to characterize autistic sensory processing in different measurement modalities.

Methods

Participants were 46 autistic and 21 typically developing 11- to 14-year-olds. Participants and their caregivers completed questionnaires regarding sensory experiences and behaviors. Auditory and somatosensory event-related potentials (ERPs) were recorded as part of a multisensory ERP task. Auditory detection, tactile static detection, and tactile spatial resolution psychophysical thresholds were measured.

Results

Sensory questionnaires strongly differentiated between autistic and typically developing individuals, while little evidence of group differences was observed in psychophysical thresholds. Crucially, the different types of measures (neurophysiological, psychophysical, questionnaire) appeared to be largely independent of one another. However, we unexpectedly found autistic participants with larger auditory Tb ERP amplitudes had reduced hearing acuity, even though all participants had hearing acuity in the non-clinical range.

Limitations

The autistic and typically developing groups were not matched on cognitive ability, although this limitation does not affect our main analyses regarding convergence of measures within autism.

Conclusion

Overall, based on these results, measures in different sensory modalities appear to capture distinct aspects of sensory processing in autism, with relatively limited convergence between questionnaires and laboratory-based tasks. Generally, this might reflect the reality that laboratory tasks are often carried out in controlled environments without background stimuli to compete for attention, a context which may not closely resemble the busier and more complex environments in which autistic people's atypical sensory experiences commonly occur. Sensory questionnaires and more naturalistic laboratory tasks may be better suited to explore autistic people's real-world sensory challenges. Further research is needed to replicate and investigate the drivers of the unexpected association we observed between auditory Tb ERP amplitudes and hearing acuity, which could represent an important confound for ERP researchers to consider in their studies.

Electrophysiological Evidence of Auditory and Cognitive Processing Deficits in Parkinson Disease

Background

Parkinson's disease (PD) patients are at increased risk for central auditory processing (CAP) deficits and cognitive dysfunction. However, behavioral assessments of CAP and cognitive processing used in a previous study by our research team found few significant differences in performance between early-stage PD patients and age-matched control subjects. The objective of this study is to use auditory event-related potentials (AERPs) to compare CAP and cognitive functions in a population of PD patients with a group of age-matched control subjects.

Methods

AERPs in response to tonal and speech stimuli were recorded from 35 adults who had a medical diagnosis of PD (23 males and 12 females; mean age = 66.9 ± s.d.11.2 years), and 35 age-matched control subjects who did not have PD or any other neurological disorders (31 males and 4 females; mean age = 65.4 ± s.d.12.3 years). Auditory stimuli included pure tones (500 and 1000 Hz) to elicit the P300 response and a dichotic digits paradigm to elicit the N200 processing negativity.

Results

Compared to control subjects, PD patients exhibited significantly longer latencies of P300 and N200 components and smaller amplitude N200 components. Latency and amplitude of the N200 component were significantly correlated with participants' age. N200 amplitude was correlated with results from the Rey Auditory Verbal Learning Test (RAVLT) of cognitive ability. Latency of the P300 and amplitude of the N200 components were significantly correlated with results from the Spatial Release From Masking (SRM) behavioral CAP assessment.

Conclusions

AERP assessments used in this study appear to be sensitive indicators of CAP and cognitive deficits exhibited by early-stage PD patients. While few significant differences in performance on behavioral CAP and cognitive tests were previously observed between this population of PD patients and age-matched control subjects, N200 and P300 components recorded in the present study revealed impaired neural processing by the PD group.

On the Relationship between P3 Latency and Mental Ability as a Function of Increasing Demands in a Selective Attention Task

The mental speed approach to individual differences in mental ability (MA) is based on the assumption of higher speed of information processing in individuals with higher than those with lower MA. Empirical support of this assumption has been inconsistent when speed was measured by means of the P3 latency in the event-related potential (ERP). The present study investigated the association between MA and P3 latency as a function of task demands on selective attention. For this purpose, 20 men and 90 women performed on a standard continuous performance test (CPT1 condition) as well as on two further task conditions with lower (CPT0) and higher demands (CPT2) on selective attention. MA and P3 latency negatively correlated in the standard CPT, and this negative relationship even increased systematically from the CPT1 to the CPT2 condition but was absent in the CPT0 condition. The present results indicate that task demands on selective attention are decisive to observe the expected shorter P3 latency in individuals with higher compared to those with lower MA.

Effects of stimulus intensity and auditory white noise on human somatosensory cognitive processing: a study using event-related potentials

Exposure to auditory white noise has been shown to facilitate cognitive function. This phenomenon is often called stochastic resonance, and a moderate amount of auditory noise has been suggested to benefit individuals in hypodopaminergic states. Previous studies using psychophysic methods reported that stochastic resonance was sensitive to stimulus intensity; however, the relationship between neural activities elicited by different stimulus intensities and auditory white noise has not yet been clarified Thus, the present study aimed to investigate the effects of stimulus intensity (Experiment 1) and auditory white noise (Experiment 2) on behavioral data (reaction time (RT), the standard deviation of RT, and error rates), and the N140 and P300 components of event-related potentials (ERPs) in somatosensory Go/No-go paradigms. The subjects had to respond to the somatosensory stimuli by pressing a button with their right thumb only after presentation of the Go stimulus. In Experiment 1 with four different stimulus intensity levels, the peak latencies of N140 and P300 became shorter, and the peak amplitudes of N140 and P300 were enhanced with increases in stimulus intensity. In Experiment 2 with weak and mild intensities under auditory white noise and control conditions, the amplitudes of Go-P300 and No-go-P300 were enhanced by white noise, irrespective of weak and mild intensities, during Go/No-go paradigms. Auditory white noise did not significantly affect the amplitude of N140 or the latencies of N140 and P300. These results suggest the presence of a characteristic cross-modal stochastic resonance in neural substrates utilizing somatosensory ERPs.

P3 Cognitive Potential in Cochlear Implant Users

Introduction  The P3 cognitive evoked potential is recorded when a subject correctly identifies, evaluates and processes two different auditory stimuli.

Objective  to evaluate the latency and amplitude of the P3 evoked potential in 26 cochlear implant users with post-lingual deafness with good or poor speech recognition scores as compared with normal hearing subjects matched for age and educational level.

Methods  In this prospective cohort study, auditory cortical responses were recorded from 26 post-lingual deaf adult cochlear implant users (19 with good and 7 with poor speech recognition scores) and 26 control subjects.

Results  There was a significant difference in the P3 latency between cochlear implant users with poor speech recognition scores (G-) and their control group (CG) ( p  = 0.04), and between G- and cochlear implant users with good speech discrimination (G+) ( p  = 0.01). We found no significant difference in the P3 latency between the CG and G+. In this study, all G- patients had deafness due to meningitis, which suggests that higher auditory function was impaired too.

Conclusion  Post-lingual deaf adult cochlear implant users in the G- group had prolonged P3 latencies as compared with the CG and the cochlear implant users in the G+ group. The amplitudes were similar between patients and controls. All G- subjects were deaf due to meningitis. These findings suggest that meningitis may have deleterious effects not only on the peripheral auditory system but on the central auditory processing as well.

P300 development across the lifespan: a systematic review and meta-analysis

Background

The P300 component of the event-related potential is a large positive waveform that can be extracted from the ongoing electroencephalogram using a two-stimuli oddball paradigm, and has been associated with cognitive information processing (e.g. memory, attention, executive function). This paper reviews the development of the auditory P300 across the lifespan.

Methodology/Principal Findings

A systematic review and meta-analysis on the P300 was performed including 75 studies (n = 2,811). Scopus was searched for studies using healthy subjects and that reported means of P300 latency and amplitude measured at Pz and mean age. These findings were validated in an independent, existing cross-sectional dataset including 1,572 participants from ages 6–87. Curve-fitting procedures were applied to obtain a model of P300 development across the lifespan. In both studies logarithmic Gaussian models fitted the latency and amplitude data best. The P300 latency and amplitude follow a maturational path from childhood to adolescence, resulting in a period that marks a plateau, after which degenerative effects begin. We were able to determine ages that mark a maximum (in P300 amplitude) or trough (in P300 latency) segregating maturational from degenerative stages. We found these points of deflection occurred at different ages.

Conclusions/Significance

It is hypothesized that latency and amplitude index different aspects of brain maturation. The P300 latency possibly indexes neural speed or brain efficiency. The P300 amplitude might index neural power or cognitive resources, which increase with maturation.

Psychometric intelligence and P3 of the event-related potentials studied with a 3-stimulus auditory oddball task

Relationship between psychometric intelligence measured with Raven's Advanced Progressive Matrices (RAPM) and event-related potentials (ERP) was examined using 3-stimulus oddball task. Subjects who had scored higher on RAPM exhibited larger amplitude of P3a component. Additional analysis using the Standardized Low Resolution Electromagnetic Tomography (sLORETA) revealed that this effect corresponds with stronger activity within the frontal cortex and the cingulate gyrus. High intelligence can also be linked with greater P3b response and stronger activity within the parietal cortex and the posterior cingulate gyrus. It may be concluded that the processes related to the initial stage of attention engagement as indexed by P3a, as well as the later stimulus evaluation and classification reflected in P3b, are more intense in subjects scoring higher on RAPM. The quality of mental abilities can therefore be related to differences of the activity in frontal and parietal brain regions.

Evidence for mental ability related individual differences in the attentional blink obtained by an analysis of the P300 component

Attentional blink (AB) refers to impaired identification of a target (T2) when this target follows a preceding target (T1) after about 150-450 ms within a stream of rapidly presented stimuli. Previous research on a possible relation between AB and mental ability (MA) turned out to be highly ambiguous. The present study investigated MA-related individual differences in consolidation of T2 in working memory during the AB as indicated by the P300 component of the event-related potential. Thirty high (HA) and 30 low MA (LA) female participants performed an AB task while their brain activity was recorded. The AB did not differ between the two groups. HA individuals exhibited a larger P300 amplitude and longer P300 latencies during the AB suggesting higher mental effort. This higher mental effort, however, did not result in better performance presumably because of more competition between target and distractor stimuli in HA than LA individuals.

Environmental Noise and P300-Based Brain-Computer Interface (BCI)

The primary purpose of this study was to systematically evaluate the overall effect of simulated environmental noise on the P300 Speller in order to obtain usability and performance data. P300 Speller is a P300-based brain-computer interface (BCI) that allows people with motor disabilities to type characters just by thinking. Two environmental noise simulations (quiet [20–40 dB], and noisy [70–120 dB]) were examined to simulate the effects of real-world noise. Results of the study indicated that although there were differences in accuracy rate and information transfer rate (ITR) between the noise and quiet conditions, the environmental noise factor was not statistically significant. On the other hand, the P300 amplitude was significantly higher in the noisy condition than in the quiet condition. Unlike the common knowledge that BCI applications are generally preferred to be performed in quiet conditions, higher noise levels seem to increase user concentration. The outcomes of this research should have a broad impact on future user interface design of BCI applications.

P300 amplitude age reductions are not caused by latency jitter

Studies of the event-related potentials (ERPs) P3a/P3b have given insights into age effects on cognitive processes in the brain, and it has been established that latency increases and amplitude decreases with age. However, if latency jitter, that is, variation in single trial latencies, is larger in elderly than in younger participants, this may create an artificial age-amplitude correlation. The aim of this article is to test whether correction for latency jitter affects the P3a/P3b age correlations. One hundred thirty-three healthy adults (20-88 years old) went through a 3-stimuli visual oddball paradigm. Latency jitter was corrected by use of a Maximum Likelihood Estimation method. The results showed that corrections for latency jitter did not significantly affect the correlations between P3a/P3b and age. It is concluded that previous reports of amplitude reduction as a function of age seem to be valid regardless of whether latency jitter correction has been applied.

Cognitive function, P3a/P3b brain potentials, and cortical thickness in aging

The purpose of the study was to assess the relationship between the P3a/P3b brain potentials, cortical thickness, and cognitive function in aging. Thirty-five younger and 37 older healthy participants completed a visual three-stimuli oddball ERP (event-related potential)-paradigm, a battery of neuropsychological tests, and MRI scans. Groups with short vs. long latency, and low vs. high amplitude, were compared on a point by point basis across the entire cortical mantle. In the young, thickness was only weakly related to P3. In the elderly, P3a amplitude effects were found in parietal areas, the temporoparietal junction, and parts of the posterior cingulate cortex. P3b latency was especially related to cortical thickness in large frontal regions. Path models with the whole sample pooled together were constructed, demonstrating that cortical thickness in the temporoparietal cortex predicted P3a amplitude, which in turn predicted executive function, and that thickness in orbitofrontal cortex predicted P3b latency, which in turn predicted fluid function. When age was included in the model, the relationship between P3 and cognitive function vanished, while the relationship between regional cortical thickness and P3 remained. It is concluded that thickness in specific cortical areas correlates with scalp recorded P3a/P3b in elderly, and that these relationships differentially mediate higher cognitive function.

P300 em sujeitos com perda auditiva

TEMA: as avaliações comportamentais e eletrofisiológicas contribuem para o entendimento do sistema auditivo e do processo de intervenção. OBJETIVO: estudar P300 em sujeitos com perda auditiva neurossensorial congênita, segundo as variáveis gênero, idade e grau da perda auditiva. MÉTODO: a presente investigação consiste em um estudo descritivo, transversal. Foram examinados 29 sujeitos, sendo 15 do gênero masculino e 14 do gênero feminino, com idade entre 11 a 42 anos. Os critérios de elegibilidade para composição da amostra foram: idade superior a 11 anos e inferior a 45 anos; ser portador de deficiência auditiva congênita severa ou profunda; não apresentar outro tipo de distúrbio; não apresentar perda auditiva central e/ou comprometimento condutivo. A primeira etapa caracterizou-se por avaliação comportamental auditiva e fisiológica que incluiu: audiometria tonal limiar (via aérea e via óssea), logoaudiometria - LDV e medidas do ganho funcional para os sujeitos que faziam uso de próteses auditivas, Imitanciometria: curva timpanométrica e pesquisa dos reflexos ipsi e contra-laterais, registro das emissões otoacústicas (EOA) - emissões otoacústicas transitórias (EOAT) e emissões otoacústicas por produto de distorção (EOAPD). A avaliação eletrofisiológica constituiu a quarta etapa do procedimento de coleta de dados e incluiu: potenciais auditivos evocados de tronco encefálico (PEATE) e de longa latência (P300). RESULTADOS: o P300 foi registrado em 17 sujeitos, com latência e amplitude média de 326,97ms e 3,76V, respectivamente. Apresentou diferenças significantes da latência em relação à idade (p < 0,03 para derivação CzA2 e p < 0,02 para derivação CzA1) e da amplitude, segundo o grau da perda auditiva (p < 0,0015). CONCLUSÃO: o P300 pode ser registrado em sujeitos com perda auditiva.

Basic information processing of neurotics and stables: An experimental ERP approach to personality and distractibility

The aim of the study was to investigate the effects of level of neuroticism on electrophysiological event-related potentials (ERPs) to different kinds of stimuli. The neuroticism items from the NEO-PI-R were administered to 168 female, right-handed undergraduates between 19 and 29 years of age. 20 highly neurotic and 22 highly stable persons underwent an ERP task that was designed to be a combination of an auditory P3a and a visual P3b oddball task. No significant differences in the P3a and P3b were detected. It is concluded that highly neurotic and highly stable persons do not differ in fast neurocognitive processing of neutral stimuli, and that cognitive differences between the groups may be located at another level in the sequence of information processing stages.

Stimulus intensity effects on P300 amplitude across repetitions of a standard auditory oddball task

An evaluation was made of whether stimulus intensity affects changes of P300 amplitude in response to repeated presentation of the target stimulus in a standard auditory oddball task. P300 latency values were also evaluated. Three samples were selected, one for each intensity used: 65, 85 and 105 dB SPL (sound pressure level). Five hundred tones (5 subblocks, 100 tones each) were presented. P300 amplitude (1) increased from Fz to Pz, (2) was larger at 105 than 65 or 85 dB SPL, (3) increased from the first to second subblock and decreased from the second subblock onwards at the three intensities, replicating our previous findings at 85 dB SPL and demonstrating a consistent phenomenon, and (4) at 105 dB SPL, the decrease was less pronounced, which we attribute to the more intense stimuli capturing the attention in a sustained manner during the task and interfering with the possible automation of the context-updating process.

Temporal dynamics of age-related differences in auditory incidental verbal learning

Auditory response profiles for a group of ten healthy young and ten healthy elderly subjects, evoked by implicit memory and delayed verbal recognition tasks, were evaluated to determine if effects of stimulus repetition could be identified in the superior temporal gyrus (STG) and prefrontal cortical regions. We hypothesized that effects of stimulus repetition should occur both early in time and at early levels of the nervous system (STG) followed by later effects in prefrontal regions. Magnetoencephalographic (MEG) responses were recorded using a whole-head MEG system and automated, multi-start analysis methods were applied to the data in order to characterize the temporal response profiles from distributed but focal, cortical regions engaged in memory-related tasks. The findings revealed a main effect of age for early activity ( approximately 50 ms) in STG which appeared to be nonspecific for Old/New words and an Age x Task interaction for late activity ( approximately 100-800 ms) in STG which was specific to Old/New words. Although the behavioral performance measures did not reveal traditional effects of response priming, the MEG measures did reveal a reduction in amplitude with stimulus repetition in young subjects. The elderly did not reveal a reduction in amplitude concomitant with stimulus repetition for either the global attributes of words or for specific Old/New words. Long duration effects of stimulus repetition noted in the present study raise the possibility that results from sensory gating, mismatch negativity and P300 paradigms may represent a continuum of stimulus repetition effects. Two of these paradigms evoke greater enhancement to novel or infrequent stimuli, or rather, greater reduction of amplitude with repetition.

Auditory P3 indexes personality traits and cognitive function in healthy men and women

The relationship of the auditory P3 event-related potential to major personality dimensions and neuropsychological performance was examined in psychiatrically healthy men and women (28 male, 15 female) recruited from the community. An auditory oddball paradigm was used to collect P3 amplitude and latency data. Personality traits were measured with the NEO Five-Factor Inventory. Several Wechsler Adult Intelligence Scale-Revised (WAIS-R) subtests, the Digit Symbol Test, and the Trail Making Test comprised the neuropsychological tests. A multivariate statistical procedure (Partial Least Squares) was used to quantify the relationships between P3 variables and personality and neuropsychological performance variables. P3 amplitude was negatively related to Neuroticism and positively related to Extraversion, Openness, Agreeableness and Conscientiousness. Better neuropsychological performance was associated with greater P3 amplitude and earlier latency. Thus, greater P3 amplitude was associated with less deviant personality scores and better neuropsychological performance in healthy subjects. Earlier P3 latency was also associated with better neuropsychological performance. The physiological significance of these relationships is not yet clear, but these results suggest that neural assemblies indexed by P3 may subserve both elemental cognition and healthy personality function.

Life-span changes in P3a

The relationship of visual P3a to age was investigated in a life-span sample. The aims of the study were (1) to assess to what extent P3a, relative to P3b, decreases with increasing age; (2) To assess at which recording sites the relationship between P3a and age is strongest; (3) to investigate whether the relationship between P3a and age is best described as linear or nonlinear. One hundred and three well-functioning adults, 20-92 years old, were given a health interview, a battery of neuropsychological tests, and performed a visual three-stimuli oddball ERP task yielding both a P3a and a P3b. P3a and age was moderately correlated, with coefficients reaching.53 (Cz) and -.52 (Pz) for latency and amplitude, respectively. P3b was to a much lesser extent related to age. Generally, the age-P3a relationship was strongest at midline and central electrodes. Finally, the relationship between age and P3a was best described as linear. P3a seems selectively more impaired with age than P3b, but this impairment seems less pronounced at Fz than at Cz and Pz. There is a need for complex theoretical integration of these and previous findings.

Rhythmic context influences the auditory evoked potentials of musicians and nonmusicians

In this study, we investigated how rhythms are processed in the brain by measuring both behaviourally obtained ratings and auditory evoked potentials (AEPs) from the EEG. We presented probe beats on seven positions within a test bar. Two bars of either a duple- or triple meter rhythm preceded probe beats. We hypothesised that sequential processing would lead to meter effects at the 1/3 and 1/2bar positions, whereas hierarchical processing would lead to context effects on the 1/3, 1/2 and 2/3bar positions. We found that metric contexts affected behavioural ratings. This effect was more pronounced for rhythmic experts. In addition, both the AEP P3a and P3b component could be identified. Though metric context affected the P3a amplitudes, group effects were less clear. We found that the AEP P3a component is sensitive to violation of temporal expectancies. In addition, behavioural data and P3a correlation coefficients (CCs) suggest that temporal patterns are processed sequentially in nonmusicians but are processed in a hierarchical way in rhythmic experts.

Rhythmic training decreases latency-jitter of omission evoked potentials (OEPs) in humans

In this study omission evoked potentials (OEPs) were studied in rhythmic experts (n=12) and non-musicians (n=12). Trains of auditory stimuli were presented. Trials (n=90) contained five omissions and started with a random number of beats, thus making every first omission unpredictable. Participants had to tap along with the first beat after the fifth omission (n=90), thus determining timing-accuracy. Single-trial OEPs elicited by every first omission were obtained by means of wavelet denoising allowing determination of latency-jitter. Clear OEPs, consisting of a slow positive wave, maximal over Pz, were observed in response to unpredictable omissions. No group differences in OEPs amplitudes or latencies were observed. However, rhythmic experts showed less latency-jitter of both the OEPs positive wave and of behavioral responses compared with non-musicians.