Auditory Event-related Potentials Components Research Articles

The relationship between event-related potential components and suicide risk in major depressive disorder

BackgroundSuicide is a serious global issue, with major depressive disorder (MDD) being a significant risk factor for suicidal thoughts and behaviors. There is an urgent need to determine whether event-related potential components (ERPs) could be used as an indicator to assess suicidal risk. MethodsFrom 2020 to 2023, 258 participants in total were recruited into the study. All participants were divided into four groups: MDD patients at high (n = 66), moderate (n = 66), and low risk (n = 56) of suicide, and healthy controls (HCs)(n = 70). Each participant provided socio-demographic information and underwent evaluations using clinical psychological scales such as 7-item Generalized Anxiety Disorder (GAD-7), Health Questionnaire-9 items (PHQ-9), and Nurses' Global Assessment of Suicide Risk (NGASR). The auditory brainstem response test and ERP examination were performed for all subjects. ResultsOur study found that the amplitude of P2–P3 and N2–P3 was significantly reduced in MDD patients at moderate and high risk of suicide, and these were negatively correlated with NGASR total score (all P < 0.05). Point B latency was positively correlated with NGASR total score (P < 0.05). Patients with MDD patients at low risk for suicide had a lower A-B amplitude compared to HCs (P < 0.05). No differences were found in MMN or P50 components between the four groups (all P > 0.05). ConclusionsMDD patients at higher risk of suicide exhibited severe impairment of cognitive function. ERP indices, such as the amplitude of P2–P3 and N2–P3, could be associated with the risk of suicide in MDD patients.

Sensory Attenuation Deficit and Auditory Hallucinations in Schizophrenia: A Causal Mechanism or a Risk Factor? Evidence From Meta-Analyses on the N1 Event-Related Potential Component

BackgroundSensory attenuation (SA), the dampened perception of self-generated sensory information, is typically associated with reduced event-related potential signals, such as for the N1 component of auditory event-related potentials. SA, together with efficient monitoring of intentions and actions, should facilitate the distinction between self-generated and externally generated sensory events, thereby optimizing interaction with the world. According to many, SA is deficient in schizophrenia. The question arises whether altered SA reflects a sufficient mechanism to explain positive symptoms such as auditory hallucinations. A systematic association of reduced auditory SA in hallucinating patients would support this hypothesis. MethodsWe conducted a series of meta-analyses on 15 studies on auditory SA in which the N1 component of event-related potential–electroencephalogram signals was measured during talking (self-generated sensory signals condition) or when listening to prerecorded vocalizations (externally generated sensory signals condition). ResultsWe found that individuals with schizophrenia did show some auditory SA because their N1 signal was significantly attenuated in talking conditions compared with listening conditions. However, the magnitude of such attenuation was reduced in individuals with schizophrenia compared to healthy control participants. This phenomenon generalizes independently from the stage of the disease, the severity of positive symptoms, and whether patients have auditory hallucinations or not. ConclusionsThese findings suggest that reduced SA cannot be a sufficient mechanism for explaining positive symptoms such as auditory hallucinations in schizophrenia. Because reduced SA was also present in participants at risk of schizophrenia, reduced SA may represent a risk factor for the disorder. We discuss the implications of these results for clinical-cognitive models of schizophrenia.

Possible Event-Related Potential Correlates of Voluntary Attention and Reflexive Attention in the Emei Music Frog.

Simple SummaryWe investigated auditory event-related potentials (ERP) related to auditory attention in music frogs. Our objective was to explore whether ERP components related to voluntary attention and reflexive attention exist in frogs. We found that the amplitudes of stimulus preceding negativity (SPN, related to voluntary attention and under up-down control) evoked by silence replacement in the telencephalon were the largest when the sequence of acoustic stimuli could be predicted, while the N1 amplitudes (related to reflexive attention and under bottom-up control) evoked in the mesencephalon were the largest when the sequence of acoustic stimuli could not be predicted. This suggests that human-like ERP components related to voluntary attention and reflexive attention exist in the lower vertebrates also.Attention, referring to selective processing of task-related information, is central to cognition. It has been proposed that voluntary attention (driven by current goals or tasks and under top-down control) and reflexive attention (driven by stimulus salience and under bottom-up control) struggle to control the focus of attention with interaction in a push–pull fashion for everyday perception in higher vertebrates. However, how auditory attention engages in auditory perception in lower vertebrates remains unclear. In this study, each component of auditory event-related potentials (ERP) related to attention was measured for the telencephalon, diencephalon and mesencephalon in the Emei music frog (Nidirana daunchina), during the broadcasting of acoustic stimuli invoking voluntary attention (using binary playback paradigm with silence replacement) and reflexive attention (using equiprobably random playback paradigm), respectively. Results showed that (1) when the sequence of acoustic stimuli could be predicted, the amplitudes of stimulus preceding negativity (SPN) evoked by silence replacement in the forebrain were significantly greater than that in the mesencephalon, suggesting voluntary attention may engage in auditory perception in this species because of the correlation between the SPN component and top-down control such as expectation and/or prediction; (2) alternately, when the sequence of acoustic stimuli could not be predicted, the N1 amplitudes evoked in the mesencephalon were significantly greater than those in other brain areas, implying that reflexive attention may be involved in auditory signal processing because the N1 components relate to selective attention; and (3) both SPN and N1 components could be evoked by the predicted stimuli, suggesting auditory perception of the music frogs might invoke the two kind of attention resources simultaneously. The present results show that human-like ERP components related to voluntary attention and reflexive attention exist in the lower vertebrates also.

O-EV002. Auditory event-related potential changes over 6 months following acute organophosphate insecticide poisoning: A follow-up study

Introduction . Ingestion of organophosphate insecticides (OPIs) is a common method of self-harm and a major clinical problem is Asia. Apart from acute cholinergic effects, OPIs are also claimed to be associated with long-term neurobehavioural deficits. However, neurophysiological evidence for such long-term deficits is scarce in humans. We aimed to assess long-term changes in the pre-attentive (N1) and attentive (P3b) components of auditory event-related potentials (ERPs) following acute OPI self-poisoning. Methods . We recruited 203 patients (147 men) hospitalised following OPI ingestion (OP Group; all had significant red cell cholinesterase inhibition) and 50 patients (23 men) hospitalised with paracetamol overdose (Control Group) as a means of self harm. We recorded their EEG in an auditory oddball task and derived the averaged ERPs. The subjects underwent three testing sessions: on discharge from hospital (around 14 days post-ingestion), 6 weeks and 6 months post-ingestion. We compared the reaction time and ERP indices of the two groups at each time point, adjusting for sex, age, education and psychiatric comorbidities in multiple regression models. Results . After adjusting for covariates, OP Group had significantly slower reaction time than the Control Group on discharge (mean difference [SE] = 65[20] ms, p = 0.001) and at 6 weeks (mean difference [SE] = 45[20] ms, p = 0.024), but not at 6 months. Parietal (PZ) P3b amplitudes were significantly smaller in the OP group on discharge (mean difference [SE] = 2.23[0.84] V, p = 0.009) and at 6 months (mean difference [SE] = 3.34[1.43] V, p = 0.021). P3b latencies or frontal (FZ) N1 component did not show significant intergroup differences. Conclusion . Acute exposure to clinically significant doses of OPIs seem to cause impairment in behavioural and neurophysiological indices of stimulus discrimination, that outlast the cholinergic phase of intoxication. The behavioural impairment seems to disappear over months, but the underlying neurophysiological deficits of attentive processing seem to last even after 6 months post-exposure.

P50, N100, and P200 Auditory Sensory Gating Deficits in Schizophrenia Patients.

BackgroundSensory gating describes neurological processes of filtering out redundant or unnecessary stimuli during information processing, and sensory gating deficits may contribute to the symptoms of schizophrenia. Among the three components of auditory event-related potentials reflecting sensory gating, P50 implies pre-attentional filtering of sensory information and N100/P200 reflects attention triggering and allocation processes. Although diminished P50 gating has been extensively documented in patients with schizophrenia, previous studies on N100 were inconclusive, and P200 has been rarely examined. This study aimed to investigate whether patients with schizophrenia have P50, N100, and P200 gating deficits compared with control subjects.MethodsControl subjects and clinically stable schizophrenia patients were recruited. The mid-latency auditory evoked responses, comprising P50, N100, and P200, were measured using the auditory-paired click paradigm without manipulation of attention. Sensory gating parameters included S1 amplitude, S2 amplitude, amplitude difference (S1-S2), and gating ratio (S2/S1). We also evaluated schizophrenia patients with PANSS to be correlated with sensory gating indices.ResultsOne hundred four patients and 102 control subjects were examined. Compared to the control group, schizophrenia patients had significant sensory gating deficits in P50, N100, and P200, reflected by larger gating ratios and smaller amplitude differences. Further analysis revealed that the S2 amplitude of P50 was larger, while the S1 amplitude of N100/P200 was smaller, in schizophrenia patients than in the controls. We found no correlations between sensory gating indices and schizophrenia positive or negative symptom clusters. However, we found a negative correlation between the P200 S2 amplitude and Bell’s emotional discomfort factor/Wallwork’s depressed factor.ConclusionTill date, this study has the largest sample size to analyze P50, N100, and P200 collectively by adopting the passive auditory paired-click paradigm without distractors. With covariates controlled for possible confounds, such as age, education, smoking amount and retained pairs, we found that schizophrenia patients had significant sensory gating deficits in P50-N100-P200. The schizophrenia patients had demonstrated a unique pattern of sensory gating deficits, including repetition suppression deficits in P50 and stimulus registration deficits in N100/200. These results suggest that sensory gating is a pervasive cognitive abnormality in schizophrenia patients that is not limited to the pre-attentive phase of information processing. Since P200 exhibited a large effect size and did not require additional time during recruitment, future studies of P50-N100-P200 collectively are highly recommended.

Applied potential of task-free event-related paradigms for assessing neurocognitive functions in disorders of consciousness.

Diagnosing patients with disorders of consciousness is immensely difficult and often results in misdiagnoses, which can have fatal consequences. Despite the severity of this well-known issue, a reliable assessment tool has not yet been developed and implemented in the clinic. The main aim of this focused review is to evaluate the various event-related potential paradigms, recorded using EEG, which may be used to improve the assessment of patients with disorders of consciousness; we also provide a brief comparison of these paradigms with other measures. Notably, most event-related potential studies on the topic have focused on testing a small set of components, or even just a single component. However, to be of practical use, we argue that an assessment should probe a range of cognitive and linguistic functions at once. We suggest a novel approach that combines a set of well-tested auditory event-related potential components: N100, mismatch negativity, P3a, N400, early left anterior negativity and lexical response enhancement. Combining these components in a single, task-free design will provide a multidimensional assessment of cognitive and linguistic processes, which may help physicians make a more precise diagnosis.

Attenuation of auditory mismatch negativity in serotonin transporter knockout mice with anxiety-related behaviors

As the first-line antidepressant drugs, selective serotonin reuptake inhibitors (SSRIs) have efficacy in controlling the symptoms of depression. However, adverse events such as anxiety and hearing disorders were usually observed in patients and even healthy volunteers during the initial phase of SSRI administration. Hearing disorders, including auditory hallucination and tinnitus, are not only highly comorbid with mental disorders but also acknowledged factors that induce psychiatric disorders. The pharmacological and neural mechanisms underlying SSRI-induced anxiety and hearing disorders are not clear. In particularly, the methods evaluating hearing disorders are not well established in animal models, limiting the pre-clinical research on its mechanism. In the present study, we examined the mismatch negativity (MMN), a cognitive component of auditory event-related potential (ERP), to evaluate the hearing process of auditory cortex in mice. Under the acute administration of citalopram, a widely used SSRI, the anxiety-related behaviors and reduced MMN were observed in mice. Serotonin transporter (SERT) is a potential target of SSRIs. The anxiety-related behaviors and reduced MMN were also observed in SERT knockout mice, implying the role of SERT in anxiety and hearing disorders induced by SSRIs. Meanwhile, the auditory brainstem response and initial components of auditory ERP were kept intact in SERT knockout mice, suggesting that hearing neural pathway is less affected by serotonergic system. Our study suggests that the SERT deficient mice might represent a useful animal model in the investigation of the anxiety and hearing disorders during the SSRI treatment.

A lateral inhibition mechanism explains the dissociation between mismatch negativity and behavioral pitch discrimination

Although mismatch negativity (MMN), a change-specific component of auditory event-related potential, is considered to be an index of sound discrimination accuracy, the amplitude of the MMN responses elicited by pitch height deviations in musicians and tone language speakers with superior pitch discrimination is usually not enhanced compared to that elicited in individuals with inferior pitch discrimination. We hypothesized that superior pitch discrimination is accompanied by enhanced lateral inhibition, a critical neural mechanism that sharpens the tuning curves of the auditory neurons in the tonotopy. Forty Mandarin-speaking healthy adults completed an auditory EEG experiment in which MMN was elicited by pitch height deviations in both pure and harmonic tones. Their behavioral pitch discrimination was indexed by the difference limens measured using pure and harmonic tones. Behavioral pitch discrimination correlated significantly with the MMN elicited by pure tones, but not by harmonic tones; this could be due to lateral inhibition strongly influencing the MMN elicited by harmonic tones but having less effect on the MMN elicited by pure tones. As lateral inhibition is a neural mechanism for attenuating the amplitude of MMN, our results support the notion that an enhanced lateral inhibition mechanism underlies superior pitch discrimination.

Stochastic game of data transmission in the presence of buffers of finite capacity

Current research aimed to investigate informational content of brainstem acoustic evoked potentials (BAEPs) and auditory cognitive event-related potential — mismatch negativity (MMN) in assessment of brain functional status and cognitive functions in patients with ischemic stroke. MMN is a component of auditory event-related potential with peak latency at 100–250 ms, which reflects automatic process of difference detection between stimuli and neurodynamic processes in auditory cortex at pre-attentive stage. Clinical and neurophysiological examination, including registration of BAEPs and MMN was performed for 22 patients (12 — with ischemic stroke in carotid circulation, 10 — without cerebrovascular diseases). According to results obtained using scales of MMSE, FAB, test with 10 words repetition and Schulte tables, patients with IS demonstrated cognitive impairment as compared to control group. During BAEPs examination, functional changes in brainstem were observed (increased latency of wave V and elongation of interpeak intervals III-V on both sides and III–V ipsilaterally) in patients with ischemic stroke. Also they demonstrated increased peak latency and decreased amplitude of MMN. It points at a decline in auditory discrimination accuracy, shortened lifetime of memory traces and deficit in involuntary attention switching and also indicates of cognitive impairment.

Differential effects of hearing impairment and age on electrophysiological and behavioral measures of speech in noise

Understanding speech in background noise is difficult for many listeners with and without hearing impairment (HI). This study investigated the effects of HI on speech discrimination and recognition measures as well as speech-evoked cortical N1-P2 and MMN auditory event-related potentials (AERPs) in background noise. We aimed to determine which AERP components can predict the effects of HI on speech perception in noise across adult listeners with and without HI. The data were collected from 18 participants with hearing thresholds ranging from within normal limits to bilateral moderate-to-severe sensorineural hearing loss. Linear mixed effects models were employed to examine how hearing impairment, age, stimulus type, and SNR listening condition affected neural and behavioral responses and what AERP components were correlated with effects of HI on speech-in-noise perception across participants. Significant effects of age were found on the N1-P2 but not on MMN, and significant effects of HI were observed on the MMN and behavioral measures. The results suggest that neural responses reflecting later cognitive processing of stimulus discrimination may be more susceptible to the effects of HI on the processing of speech in noise than earlier components that signal the sensory encoding of acoustic stimulus features. Objective AERP responses were also potential neural predictors of speech perception in noise across participants with and without HI, which has implications for the use of AERPs as a potential clinical tool for assessing speech perception in noise.

The Relationship between Mismatch Negativity and the COMTVal108/158Met Genotype in Schizophrenia

Mismatch negativity (MMN) is a component of auditory event-related potentials that reflects automatic change detection in the brain, showing qualities of endophenotypes in schizophrenia. MMN deficiency is one of the robust findings in patients, and it reflects both cognitive and functional decline. Catechol-o-methyltransferase (COMT) is a key enzyme involved in regulating dopamine transmission within the prefrontal cortex. A preliminary study suggested that the COMTVal108/158Met genotype (rs4680) is related to cognitive function in schizophrenia. Both the COMTVal108/158Met genotype and MMN are related to cognitive function, but no studies have reported on the relationship between MMN and the COMTVal108/158Met genotype in schizophrenia. This study therefore examined the relationship between COMTVal108/158Met genotype and MMN. The duration of MMN was measured, and the COMTVal108/158Met polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism in 49 Japanese schizophrenia patients (Val/Val, n = 21; Met carriers, n = 28). Amplitude and latency of MMN were compared between Val/Val and Met carriers.

Genetic Association between Alzheimer's Disease Risk Variant of the PICALM Gene and Auditory Event-Related Potentials in Aging.

Aging and genetic predisposition are major risk factors in age-related neurodegenerative disorders. The most common neurodegenerative disorder is Alzheimer's disease (AD). Genome-wide association studies (GWAS) have identified statistically significant association of the PICALM rs3851179 polymorphism with AD. The PICALM G allele increases the risk of AD, while the A allele has a protective effect. We examined the association of the PICALM rs3851179 polymorphism with parameters of the P3 component of auditory event-related potentials (ERPs) in 87 non-demented volunteers (age, 19-77 years) subdivided into two cohorts younger and older than 50 years of age. We found statistically significant association between the AD risk variant PICALM GG and increase in the P3 latency in subjects over 50 years old. The age-dependent increase in the P3 latency was more pronounced in the PICALM GG carriers than in the carriers of the PICALM AA and PICALM AG genotypes. The observed PICALM-associated changes in the neurophysiological processes indicate a decline in the information processing speed with aging due, probably, to neuronal dysfunction and subclinical neurodegeneration of the neuronal networks in the hippocampus and the frontal and parietal cortical areas. Such changes were less pronounced in the carriers of the PICALM gene A allele, which might explain the protective effect of this allele in the cognitive decline and AD development.

Aberrant Cortical Event-Related Potentials During Associative Learning in Rat Models for Presymptomatic Stages of Alzheimer's Disease.

Trace eyeblink conditioning is a hippocampus-dependent associative learning paradigm which is impaired in patients with Alzheimer's disease (AD) and animal AD models. Learning in this paradigm accompanies changes in oscillatory activity in forebrain regions, some of which are loci of pathogenic changes in prodromal AD stages. These observations motivated us to examine how cortical event-related potentials (ERPs) during this paradigm are affected by two features of the asymptomatic, AD-related brain abnormality, entorhinal tau accumulation and mild cholinergic deficit. Adult rats received viral overexpression of P301L mutant human tau in the entorhinal cortex, low-dose scopolamine treatment, or both. Electroencephalograms were recorded with epidural electrodes on the surface of the frontal, parietal, and temporal cortices during differential and reversal trace eyeblink conditioning. All rats developed conditioned responses to one of two stimuli (auditory or visual) paired with mild eyelid shock (CS+), but not to the other stimulus presented alone(CS-). They were also able to adjust the response when the stimulus contingency was reversed. With learning, the amplitude of several ERP components in the frontal and temporal cortices came to differentiate the CS+ from CS-. Scopolamine affected the learning-related change in temporal P2 and other learning-unrelated components in three regions. Entorhinal tau overexpression primary affected the amplitude of temporal visual ERPs and learning-unrelated frontal and temporal auditory ERP components. The double manipulation only affected two components of temporal auditory ERPs. Thus, cortical ERPs during differential associative learning are sensitive to asymptomatic brain abnormality associated with AD.

Analysis of Age-Related Dynamics and Gender-Specific Characteristics of Spontaneous Bioelectrical Activity and Components of Auditory Evoked Potentials in Junior School Students Living in the Arctic Region of the Russian Federation

We studied neurophysiological characteristics of the age-related development in junior school students (7–8 and 10–11 years of age) living in the Arctic region of the Russian Federation. The background electroencephalograms (EEGs) were recorded during quiet wakefulness with the eyes closed and open, and event related potentials (ERP) were recorded during the passive perception of sound stimuli within the oddball paradigm in the group of children (33 subjects, 18 boys and 15 girls). A decrease of the latency period and the spatial rearrangement of mismatch negativity with an increase in the amplitude in the centrofrontal cortex have been revealed in the groups of children aged 10–11 years during the perception of a rare stimulus and a decrease of the latency period of the Р300 component in the central and parietal areas associated with the maturation of mechanisms for involuntary auditory attention. Age-specific differences in the components of auditory ERP (N1 and N2) have been shown during passive perception of rare and frequent sounds, which reflect the processes of the morphofunctional maturation of the brain cortex in healthy Arctic school students (an increase of the N1 component amplitude, a decrese of the amplitude and the latency period of the N2 component). The analysis of the background EEG characteristics has shown both the common features, such as a decrease with age of the EEG power in the Δ and θ bands in the eyes-open state, and the different direction and topographic specificities in the age-dependent reorganization of bioelectrical activity in boys and girls in the α1 and α2 EEG bands.

Changes of auditory event-related potentials in ovariectomized rats injected with d-galactose: Protective role of rosmarinic acid

Rosmarinic acid (RA), which has multiple bioactive properties, might be a useful agent for protecting central nervous system against age related alterations. In this context, the purpose of the present study was to investigate possible protective effects of RA on mismatch negativity (MMN) component of auditory event-related potentials (AERPs) as an indicator of auditory discrimination and echoic memory in the ovariectomized (OVX) rats injected with d-galactose combined with neurochemical and histological analyses. Ninety female Wistar rats were randomly divided into six groups: sham control (S); RA-treated (R); OVX (O); OVX+RA-treated (OR); OVX+d-galactose-treated (OD); OVX+d-galactose+RA-treated (ODR). Eight weeks later, MMN responses were recorded using the oddball condition. An amplitude reduction of some components of AERPs was observed due to ovariectomy with or without d-galactose administiration and these reduction patterns were diverse for different electrode locations. MMN amplitudes were significantly lower over temporal and right frontal locations in the O and OD groups versus the S and R groups, which was accompanied by increased thiobarbituric acid reactive substances (TBARS) and hydroxy-2-nonenal (4-HNE) levels. RA treatment significantly increased AERP/MMN amplitudes and lowered the TBARS/4-HNE levels in the OR and ODR groups versus the O and OD groups, respectively. Our findings support the potential benefit of RA in the prevention of auditory distortion related to the estrogen deficiency and d-galactose administration at least partly by antioxidant actions.

Nicotine enhances an auditory Event-Related Potential component which is inversely related to habituation.

Nicotine is a psychoactive substance that is commonly consumed in the context of music. However, the reason why music and nicotine are co-consumed is uncertain. One possibility is that nicotine affects cognitive processes relevant to aspects of music appreciation in a beneficial way. Here we investigated this possibility using Event-Related Potentials. Participants underwent a simple decision-making task (to maintain attentional focus), responses to which were signalled by auditory stimuli. Unlike previous research looking at the effects of nicotine on auditory processing, we used complex tones that varied in pitch, a fundamental element of music. In addition, unlike most other studies, we tested non-smoking subjects to avoid withdrawal-related complications. We found that nicotine (4.0 mg, administered as gum) increased P2 amplitude in the frontal region. Since a decrease in P2 amplitude and latency is related to habituation processes, and an enhanced ability to disengage from irrelevant stimuli, our findings suggest that nicotine may cause a reduction in habituation, resulting in non-smokers being less able to adapt to repeated stimuli. A corollary of that decrease in adaptation may be that nicotine extends the temporal window during which a listener is able and willing to engage with a piece of music.

Topography of Activity Evoked in the Human Brain during Discrimination of Moving Sound Stimuli

The aim of the present work was to assess interhemisphere asymmetry of the N1, P2, and N250 components of auditory event-related potentials (ERP) and mismatch negativity (MMN) in passive discrimination between moving sound stimuli in an oddball paradigm. Stimulus movement was created using a linear increase in the interaural time delay ΔT in dichotically presented signals. The amplitudes of the N1 and P2 components were greater in the right hemisphere, this being particularly clear in the frontolateral area. The amplitude of the N250 component in the frontolateral and frontomedial areas was greater in the hemisphere contralateral to the sound stimulus. The direction of movement of sound stimuli had no effect on the asymmetry of ERP and MMN components. The right-hemisphere asymmetry of N1 increased with increases in stimulus speed, while asymmetry of P2 was maximal for short movement trajectories. Asymmetry of N250 and MMN was identified in terms of differences between standards and deviants, i.e., a higher-order feature. Thus, these studies demonstrated differences in the nature of interhemisphere asymmetry for the early and late ERP components, reflecting differences in the neural structures supporting primary analysis of the stimulus and higher cognitive processes.

Cognitive impairments in patients with first episode psychosis: The relationship between neurophysiological and neuropsychological assessments

Cognitive deficits in schizophrenia have been widely reported. Neurophysiological and neuropsychological assessments have been conducted to study these impairments. Event-related potentials (ERPs) are relevant markers of cognitive deficits in schizophrenia, and reductions in specific ERP components have been found. The MATRICS Consensus Cognitive Battery (MCCB) was developed to obtain a consensus battery for the assessment of cognitive deficits in schizophrenia. Here, we aimed to study modulations of several ERP components in first episode psychosis (FEP). We also examined neuropsychological deficits using the MCCB, and correlations between ERP and MCCB impairments. Thirty-eight FEP patients were compared to thirty-eight healthy controls. The following ERP components were examined: P1, N1, MMN, P2, early-P3 and late-P3. We used an auditory three-stimulus oddball paradigm, with standard (60%), target (20%) and distractor (20%) stimuli. FEP patients showed significantly lower amplitudes of P2, early-P3 and late-P3 components. FEP patients also showed significant deficits in all the MCCB cognitive domains. Finally, correlational analyses found strong associations between amplitudes of P2, early-P3 and late-P3 components and MCCB tests for attention and speed of processing. These findings indicate that deficits in late auditory ERP components are present in FEP, whereas early components are preserved. These reductions in late ERP components were related to attentional deficits in FEP as assessed by MCCB. These findings indicate that MCCB is a valid battery for studying cognitive impairments in the initial stages of schizophrenia, and highlight the utility of converging neurophysiological and neuropsychological measures to examine attentional impairments in schizophrenia.

The N1 event-related potential component as an index of speech sound encoding for multiple phonetic contrasts

Listeners rely on many phonetic cues to perceive speech, but it is not clear how acoustic and phonological differences are encoded at early stages of perception. Previous work has begun to address this using the event-related potential (ERP) technique, demonstrating that the amplitude of the auditory N1 ERP component varies linearly with differences along VOT continua and suggesting that it can serve as an index of cue encoding. However, it is not clear how the N1 varies more generally for other phonetic distinctions. We present ERP data for a large set of naturally-produced word-initial minimal pairs spanning 18 consonants (/b,d,tʃ,f,g,dʒ,k,l,m,n,p,ɹ,s,ʃ,t,v,w,z/), as well as stimuli varying along voice onset time (voicing) and burst frequency (place of articulation) continua for all six stop consonants. The results reveal widespread differences in N1 amplitude for place of articulation and voicing. The N1 is larger for voiced consonants than voiceless consonants. Moreover, N1 amplitude as a function of place of articulation patterns differently for fricatives (larger N1 for alveolar and post-alveolar phonemes) than for stops (smaller N1 for these place of articulation categories). Overall, these results suggest that the N1 serves as a useful index of speech sound encoding across a range of phonetic contrasts.

Cortical auditory evoked potentials (CAEPs) represent neural cues relevant to pitch perception.

Components of auditory event-related potentials (ERPs) may represent various aspects of the cortical processing of pitch. However, evidence hints an earlier representation of pitch perception in auditory ERPs of cortical origin. In this study, we examined whether earlier waves in cortical auditory evoked potentials (CAEPs) might reflect pitch-relevant features of both listeners and stimuli. CAEPs were elicited by pure tones and sweeping tones, and individual behavioral performance in pitch discrimination reflected by frequency difference limen (FDL) was also measured. Results show that CAEPs evoked by sweeping tones significantly correlate to FDL around ~50 ms, but CAEPs evoked by pure tones do not. Also, CAEPs are significantly affected by pitch-shift direction around ~130 ms. CAEPs evoked by ascending sweeping tones are larger in magnitude than those evoked by descending ones. Therefore, listeners' personal attributes relevant to pitch perception have already been reflected at a very early stage of cortical auditory processing, whilst certain pitch-related features of stimuli are recognized and represented at a later stage.