Auditory processing that leads to conscious perception: A unique window to central auditory processing opened by the mismatch negativity and related responses

Cortical responses to looming sources are explained away by the auditory periphery

A wealth of behavioral evidence indicate that sounds with increasing intensity (i.e. appear to be looming towards the listener) are processed with increased attentional and physiological resources compared to receding sounds. However, the neurophysiological mechanism responsible for such cognitive amplification remains elusive. Here, we show that the large differences seen between cortical responses to looming and receding sounds are in fact almost entirely explained away by nonlinear encoding at the level of the auditory periphery. We collected electroencephalography (EEG) data during an oddball paradigm to elicit mismatch negativity (MMN) and others Event Related Potentials (EPRs), in response to deviant stimuli with both dynamic (looming and receding) and constant level (flat) differences to the standard in the same participants. We then combined a computational model of the auditory periphery with generative EEG methods (temporal response functions, TRFs) to model the single-participant ERPs responses to flat deviants, and used them to predict the effect of the same mechanism on looming and receding stimuli. The flat model explained 45% variance of the looming response, and 33% of the receding response. This provide striking evidence that difference wave responses to looming and receding sounds result from the same cortical mechanism that generate responses to constant-level deviants: all such differences are the sole consequence of their particular physical morphology getting amplified and integrated by peripheral auditory mechanisms. Thus, not all effects seen cortically proceed from top-down modulations by high-level decision variables, but can rather be performed early and efficiently by feed-forward peripheral mechanisms that evolved precisely to sparing subsequent networks with the necessity to implement such mechanisms.

Auditory Processing of Intonational Rises and Falls in German: Rises Are Special in Attention Orienting

This article investigates the processing of intonational rises and falls when presented unexpectedly in a stream of repetitive auditory stimuli. It examines the neurophysiological correlates (ERPs) of attention to these unexpected stimuli through the use of an oddball paradigm where sequences of repetitive stimuli are occasionally interspersed with a deviant stimulus, allowing for elicitation of an MMN. Whereas previous oddball studies on attention toward unexpected sounds involving pitch rises were conducted on nonlinguistic stimuli, the present study uses as stimuli lexical items in German with naturalistic intonation contours. Results indicate that rising intonation plays a special role in attention orienting at a pre-attentive processing stage, whereas contextual meaning (here a list of items) is essential for activating attentional resources at a conscious processing stage. This is reflected in the activation of distinct brain responses: Rising intonation evokes the largest MMN, whereas falling intonation elicits a less pronounced MMN followed by a P3 (reflecting a conscious processing stage). Subsequently, we also find a complex interplay between the phonological status (i.e., accent/head marking vs. boundary/edge marking) and the direction of pitch change in their contribution to attention orienting: Attention is not oriented necessarily toward a specific position in prosodic structure (head or edge). Rather, we find that the intonation contour itself and the appropriateness of the contour in the linguistic context are the primary cues to two core mechanisms of attention orienting, pre-attentive and conscious orientation respectively, whereas the phonological status of the pitch event plays only a supplementary role.

Concurrent Encoding of Sequence Predictability and Event-Evoked Prediction Error in Unfolding Auditory Patterns

Human listeners possess an innate capacity to discern patterns within rapidly unfolding sensory input. Core questions, guiding ongoing research, focus on the mechanisms through which these representations are acquired and whether the brain prioritizes or suppresses predictable sensory signals. Previous work, using fast auditory sequences (tone-pips presented at a rate of 20 Hz), revealed sustained response effects that appear to track the dynamic predictability of the sequence. Here, we extend the investigation to slower sequences (4 Hz), permitting the isolation of responses to individual tones. Stimuli were 50 ms tone-pips, ordered into random (RND) and regular (REG; a repeating pattern of 10 frequencies) sequences; Two timing profiles were created: in "fast" sequences, tone-pips were presented in direct succession (20 Hz); in "slow" sequences, tone-pips were separated by a 200 ms silent gap (4 Hz). Naive participants (N = 22; both sexes) passively listened to these sequences, while brain responses were recorded using magnetoencephalography (MEG). Results unveiled a heightened magnitude of sustained brain responses in REG when compared to RND patterns. This manifested from three tones after the onset of the pattern repetition, even in the context of slower sequences characterized by extended pattern durations (2,500 ms). This observation underscores the remarkable implicit sensitivity of the auditory brain to acoustic regularities. Importantly, brain responses evoked by single tones exhibited the opposite pattern-stronger responses to tones in RND than REG sequences. The demonstration of simultaneous but opposing sustained and evoked response effects reveals concurrent processes that shape the representation of unfolding auditory patterns.

Assessing mismatch negativity (MMN) and P3b within-individual sensitivity - A comparison between the local-global paradigm and two specialized oddball sequences

Mismatch negativity (MMN) and P3b are well known for their clinical utility. There exists no gold standard, however, for acquiring them as EEG markers of consciousness in clinical settings. This may explain why the within-individual sensitivity of MMN/P3b paradigms is often quite poor and why seemingly identical EEG markers can behave differently across Disorders of consciousness (DoC) studies. Here, we compare two traditional paradigms for MMN or P3b assessment with the recently more popular local-global paradigm that promises to assess MMN and P3b orthogonally within one oddball sequence. All three paradigms were administered to healthy participants (N = 15) with concurrent EEG. A clear MMN and local effect were found for 15/15 participants. The P3b and global effect were found for 14/15 and 13/15 participants, respectively. There were no systematic differences between the global effect and P3b. Indeed, P3b amplitude was highly correlated across paradigms. The local effect differed clearly from the MMN, however. It occurred earlier than MMN and was followed by a much more prominent P3a. The peak latencies and amplitudes were also not correlated across paradigms. Caution should therefore be exercised when comparing the local effect and MMN across studies. We conclude that the within-individual MMN sensitivity is adequate for both the local-global and a dedicated MMN paradigm. The within-individual sensitivity of P3b was lower than expected for both the local-global and a dedicated P3b paradigm, which may explain the often-low sensitivity of P3b paradigms in patients with DoC.

Contribution of inter-trial phase coherence at theta, alpha, and beta frequencies in auditory change detection

Introduction

Auditory change detection is a pre-attentive cortical auditory processing ability. Many neurological and psychological disorders can lead to defects in this process. Some studies have shown that phase synchronization may be related to auditory discrimination. However, the specific contributions of phase synchronization at different frequencies remain unclear.

Methods

We analyzed the electroencephalogram (EEG) data of 29 healthy adults using an oddball paradigm consisting of a standard stimulus and five deviant stimuli with varying frequency modulation patterns, including midpoint frequency transitions and linear frequency modulation. We then compared the peak amplitude and latency of inter-trial phase coherence (ITC) at the theta(θ), alpha(α), and beta(β) frequencies, as well as the N1 component, and their relationships with stimulus changes. At the same time, the characteristics of inter-trial phase coherence in response to the pure tone stimulation and chirp sound with a fine time-frequency structure were also assessed.

Result

When the stimulus frequency did not change relative to the standard stimulus, the peak latency of phase coherence at β and α frequencies was consistent with that of the N1 component. The inter-trial phase coherence at β frequency (β-ITC)served as a faster indicator for detecting frequency transition when the stimulus frequency was changed relative to the standard stimulus. β-ITC demonstrates temporal stability when detecting pure sinusoidal tones and their frequency changes, and is less susceptible to interference from other neural activities. The phase coherence at θ frequency could integrate the frequency and temporal characteristics of deviant into a single representation, which can be compared with the memory trace formed by the standard stimulus, thus effectively identifying auditory changes. Pure sinusoidal tone stimulation could induce higher inter-trial phase coherence in a smaller time window, but chirp sounds with a fine time-frequency structure required longer latencies to achieve phase coherence.

Conclusion

Phase coherence at theta, alpha, and beta frequencies are all involved in auditory change detection, but play different roles in this automatic process. Complex time-frequency modulated stimuli require longer processing time for effective change detection.

Trait and State Anxiety Effects on Mismatch Negativity and Sensory Gating Event-Related Potentials

We used the auditory roving oddball to investigate whether individual differences in self-reported anxiety influence event-related potential (ERP) activity related to sensory gating and mismatch negativity (MMN). The state-trait anxiety inventory (STAI) was used to assess the effects of anxiety on the ERPs for auditory change detection and information filtering in a sample of thirty-six healthy participants. The roving oddball paradigm involves presentation of stimulus trains of auditory tones with certain frequencies followed by trains of tones with different frequencies. Enhanced negative mid-latency response (130-230 ms post-stimulus) was marked at the deviant (first tone) and the standard (six or more repetitions) tone at Fz, indicating successful mismatch negativity (MMN). In turn, the first and second tone in a stimulus train were subject to sensory gating at the Cz electrode site as a response to the second stimulus was suppressed at an earlier latency (40-80 ms). We used partial correlations and analyses of covariance to investigate the influence of state and trait anxiety on these two processes. Higher trait anxiety exhibited enhanced MMN amplitude (more negative) (F(1,33) = 14.259, p = 6.323 × 10-6, ηp2 = 0.302), whereas state anxiety reduced sensory gating (F(1,30) = 13.117, p = 0.001, ηp2 = 0.304). Our findings suggest that high trait-anxious participants demonstrate hypervigilant change detection to deviant tones that appear more salient, whereas increased state anxiety associates with failure to filter out irrelevant stimuli.

Markov chains as a proxy for the predictive memory representations underlying mismatch negativity

Events not conforming to a regularity inherent to a sequence of events elicit prediction error signals of the brain such as the Mismatch Negativity (MMN) and impair behavioral task performance. Events conforming to a regularity lead to attenuation of brain activity such as stimulus-specific adaptation (SSA) and behavioral benefits. Such findings are usually explained by theories stating that the information processing system predicts the forthcoming event of the sequence via detected sequential regularities. A mathematical model that is widely used to describe, to analyze and to generate event sequences are Markov chains: They contain a set of possible events and a set of probabilities for transitions between these events (transition matrix) that allow to predict the next event on the basis of the current event and the transition probabilities. The accuracy of such a prediction depends on the distribution of the transition probabilities. We argue that Markov chains also have useful applications when studying cognitive brain functions. The transition matrix can be regarded as a proxy for generative memory representations that the brain uses to predict the next event. We assume that detected regularities in a sequence of events correspond to (a subset of) the entries in the transition matrix. We apply this idea to the Mismatch Negativity (MMN) research and examine three types of MMN paradigms: classical oddball paradigms emphasizing sound probabilities, between-sound regularity paradigms manipulating transition probabilities between adjacent sounds, and action-sound coupling paradigms in which sounds are associated with actions and their intended effects. We show that the Markovian view on MMN yields theoretically relevant insights into the brain processes underlying MMN and stimulates experimental designs to study the brain's processing of event sequences.

Mismatch negativity as a marker of auditory pattern separation

To what extent does incidental encoding of auditory stimuli influence subsequent episodic memory for the same stimuli? We examined whether the mismatch negativity (MMN), an event-related potential generated by auditory change detection, is correlated with participants' ability to discriminate those stimuli (i.e. targets) from highly similar lures and from dissimilar foils. We measured the MMN in 30 young adults (18-32 years, 18 females) using a passive auditory oddball task with standard and deviant 5-tone sequences differing in pitch contour. After exposure, all participants completed an incidental memory test for old targets, lures, and foils. As expected, participants at test exhibited high sensitivity in recognizing target items relative to foils and lower sensitivity in recognizing target items relative to lures. Notably, we found a significant correlation between MMN amplitude and lure discrimination, but not foil discrimination. Our investigation shows that our capacity to discriminate sensory inputs at encoding, as measured by the MMN, translates into precision in memory for those inputs.

Long-term phonemic representations become audiovisual by mid-childhood

In earlier work with adults, we showed that long-term phonemic representations are audiovisual, meaning that they contain information on typical mouth shape during articulation. Many aspects of audiovisual processing have a prolonged developmental course, often not reaching maturity until late adolescence. In this study, we examined the status of phonemic representations in two groups of children - 8-9-year-olds and 11-12-year-olds. We used the same audiovisual oddball paradigm as in the earlier study with adults (Kaganovich and Christ, 2021). On each trial, participants saw a face and heard one of two vowels. One vowel occurred frequently (standard), while another occurred rarely (deviant). In one condition (neutral), the face had a closed, non-articulating mouth. In the other condition (audiovisual violation), the mouth shape matched the frequent vowel. Although stimuli were audiovisual in both conditions, we hypothesized that identical auditory changes would be perceived differently by participants. Namely, in the neutral condition, deviants violated only the audiovisual pattern specific to each experimental block. By contrast, in the audiovisual violation condition, deviants additionally violated long-term representations for how a speaker's mouth looks during articulation. We compared the amplitude of MMN and P3 components elicited by deviants in the two conditions. In the 11-12-year-old group, the pattern of neural responses was similar to that in adults - namely, they had a larger MMN component in the audiovisual compared to neutral condition, with no major difference in the P3 amplitude. In contrast, in the 8-9-year-old group, we saw a posterior MMN in the neutral condition only and a larger P3 in the audiovisual violation compared to the neutral condition. The larger P3 in the audiovisual violation condition suggests that younger children did perceive deviants as being more attention-grabbing when they violated the typical combination of sound and mouth shape. Yet, at this age, the earlier, more automatic stages of phonemic processing indexed by the MMN component may not yet encode visual speech elements the same way they do in older children and adults. We conclude that phonemic representations do not become audiovisual until 11-12 years of age.

Possibility of additive effects by the presentation of visual information related to distractor sounds on the contra-sound effects of the N100m responses

Auditory-evoked responses can be affected by different types of contralateral sounds or by attention modulation. The present study examined the additive effects of presenting visual information about contralateral sounds as distractions during dichotic listening tasks on the contralateral effects of N100m responses in the auditory-evoked cortex in 16 subjects (12 males and 4 females). In magnetoencephalography, a tone-burst of 500 ms duration at a frequency of 1000 Hz was played to the left ear at a level of 70 dB as a stimulus to elicit the N100m response, and a movie clip was used as a distractor stimulus under audio-only, visual-only, and audio-visual conditions. Subjects were instructed to pay attention to the left ear and press the response button each time they heard a tone-burst stimulus in their left ear. The results suggest that the presentation of visual information related to the contralateral sound, which worked as a distractor, significantly suppressed the amplitude of the N100m response compared with only the contralateral sound condition. In contrast, the presentation of visual information related to contralateral sound did not affect the latency of the N100m response. These results suggest that the integration of contralateral sounds and related movies may have resulted in a more perceptually loaded stimulus and reduced the intensity of attention to tone-bursts. Our findings suggest that selective attention and saliency mechanisms may have cross-modal effects on other modes of perception.

Computational Modeling of Oddball Sequence Processing Exposes Common and Differential Auditory Network Changes in First-Episode Schizophrenia-Spectrum Disorders and Schizophrenia

BACKGROUND AND HYPOTHESIS

Differences in sound relevance filtering in schizophrenia are proposed to represent a key index of biological changes in brain function in the illness. This study featured a computational modeling approach to test the hypothesis that processing differences might already be evident in first-episode, becoming more pronounced in the established illness.

STUDY DESIGN

Auditory event-related potentials to a typical oddball sequence (rare pitch deviations amongst regular sounds) were recorded from 90 persons with schizophrenia-spectrum disorders (40 first-episode schizophrenia-spectrum, 50 established illness) and age-matched healthy controls. The data were analyzed using dynamic causal modeling to identify the changes in effective connectivity that best explained group differences.

STUDY RESULTS

Group differences were linked to intrinsic (within brain region) connectivity changes. In activity-dependent measures these were restricted to the left auditory cortex in first-episode schizophrenia-spectrum but were more widespread in the established illness. Modeling suggested that both established illness and first-episode schizophrenia-spectrum groups expressed significantly lower inhibition of inhibitory interneuron activity and altered gain on superficial pyramidal cells with the data indicative of differences in both putative N-methyl-d-aspartate glutamate receptor activity-dependent plasticity and classic neuromodulation.

CONCLUSIONS

The study provides further support for the notion that examining the ability to alter responsiveness to structured sound sequences in schizophrenia and first-episode schizophrenia-spectrum could be informative to uncovering the nature and progression of changes in brain function during the illness. Furthermore, modeling suggested that limited differences present at first-episode schizophrenia-spectrum may become more expansive with illness progression.

Auditory representations for long lasting sounds: Insights from event-related brain potentials and neural oscillations

The basic features of short sounds, such as frequency and intensity including their temporal dynamics, are integrated in a unitary representation. Knowledge on how our brain processes long lasting sounds is scarce. We review research utilizing the Mismatch Negativity event-related potential and neural oscillatory activity for studying representations for long lasting simple versus complex sounds such as sinusoidal tones versus speech. There is evidence for a temporal constraint in the formation of auditory representations: Auditory edges like sound onsets within long lasting sounds open a temporal window of about 350 ms in which the sounds' dynamics are integrated into a representation, while information beyond that window contributes less to that representation. This integration window segments the auditory input into short chunks. We argue that the representations established in adjacent integration windows can be concatenated into an auditory representation of a long sound, thus, overcoming the temporal constraint.

Plasticity Changes in Central Auditory Systems of School-Age Children Following a Brief Training With a Remote Microphone System

OBJECTIVES

The objective of this study was to investigate whether a brief speech-in-noise training with a remote microphone (RM) system (favorable listening condition) would contribute to enhanced post-training plasticity changes in the auditory system of school-age children.

DESIGN

Before training, event-related potentials (ERPs) were recorded from 49 typically developing children, who actively identified two syllables in quiet and in noise (+5 dB signal-to-noise ratio [SNR]). During training, children completed the same syllable identification task as in the pre-training noise condition, but received feedback on their performance. Following random assignment, half of the sample used an RM system during training (experimental group), while the other half did not (control group). That is, during training' children in the experimental group listened to a more favorable speech signal (+15 dB SNR) than children from the control group (+5 dB SNR). ERPs were collected after training at +5 dB SNR to evaluate the effects of training with and without the RM system. Electrical neuroimaging analyses quantified the effects of training in each group on ERP global field power (GFP) and topography, indexing response strength and network changes, respectively. Behavioral speech-perception-in-noise skills of children were also evaluated and compared before and after training. We hypothesized that training with the RM system (experimental group) would lead to greater enhancement of GFP and greater topographical changes post-training than training without the RM system (control group). We also expected greater behavioral improvement on the speech-perception-in-noise task when training with than without the RM system.

RESULTS

GFP was enhanced after training only in the experimental group. These effects were observed on early time-windows corresponding to traditional P1-N1 (100 to 200 msec) and P2-N2 (200 to 400 msec) ERP components. No training effects were observed on response topography. Finally, both groups increased their speech-perception-in-noise skills post-training.

CONCLUSIONS

Enhanced GFP after training with the RM system indicates plasticity changes in the neural representation of sound resulting from listening to an enriched auditory signal. Further investigation of longer training or auditory experiences with favorable listening conditions is needed to determine if that results in long-term speech-perception-in-noise benefits.

Electrophysiological biomarkers and age characterize phenotypic heterogeneity among individuals with major depressive disorder

Introduction: Despite the high need for effective treatments for major depressive disorder (MDD), the development of novel medicines is hampered by clinical, genetic and biological heterogeneity, unclear links between symptoms and neural dysfunction, and tenuous biomarkers for clinical trial contexts of use. Methods: In this study, we examined the International Study to Predict Optimized Treatment in Depression (iSPOT-D) clinical trial database for new relationships between auditory event-related potential (ERP) responses, demographic features, and clinical symptoms and behavior, to inform strategies for biomarker-driven patient stratification that could be used to optimize future clinical trial design and drug development strategy in MDD. Results: We replicate findings from previous analyses of the classic auditory oddball task in the iSPOT-D sample showing smaller than typical N1 and P300 response amplitudes and longer P300 latencies for target and standard stimuli in patients with MDD, suggesting altered bottom-up sensory and top-down attentional processes. We further demonstrate that age is an important contributor to clinical group differences, affecting both topographic distribution of the clinically informative ERP responses and the types of the stimuli sensitive to group differences. In addition, the observed brain-behavior associations indicate that levels of anxiety and stress are major contributing factors to atypical sensory and attentional processing among patients with MDD, particularly in the older subgroups. Discussion: Our novel findings support the possibility of accelerated cognitive aging in patients with MDD and identify the frontal P300 latency as an additional candidate biomarker of MDD. These results from a large, well-phenotyped sample support the view that heterogeneity of the clinical population with MDD can be systematically characterized based on age and neural biomarkers of sensory and attentional processing, informing patient stratification strategies in the design of clinical trials.

Temporal processing deficit in children and adolescents with autism spectrum disorder: An online assessment

Objective

The sensory deficit has been considered as one of the core features in children and adolescents with autism spectrum disorder (ASD). The present study aimed to examine the temporal processing of simple and more complex auditory inputs in ASD children and adolescents with an online assessment that can be conducted remotely.

Methods

One hundred fifty-eight children and adolescents aged 5-17 years participated in this study, including 79 ASD participants and 79 typically developing (TD) participants. The online assessment consisted of two temporal-order judgment tasks that required repeating the sequence of two pure tones or consonant-vowel (CV) syllabic pairs at varying interstimulus intervals (ISIs).

Results

Significantly lower accuracy rates were found in ASD than TD participants in the pure tone and the CV conditions with both short and long ISI. In addition, ASD participants (M  =  245.97 ms) showed a significantly higher passing threshold than TD participants (M  =  178.84 ms) in the CV task. Receiver operating characteristic analysis found that the age × ISI passing threshold composite yielded a sensitivity of 74.7% and a specificity of 50.6% at the cutoff point of -0.307 in differentiating ASD participants from TD participants.

Conclusion

In sum, children and adolescents with ASD showed impaired temporal processing of both simple and more complex auditory stimuli, and the online assessment seems to be sensitive in differentiating individuals with ASD from those with TD.

The impacts of training on change deafness and build-up in a flicker task

Performance on auditory change detection tasks can be improved by training. We examined the stimulus specificity of these training effects in behavior and ERPs. A flicker change detection task was employed in which spatialized auditory scenes were alternated until a "change" or "same" response was made. For half of the trials, scenes were identical. The other half contained changes in the spatial locations of objects from scene to scene. On Day 1, participants were either trained on this auditory change detection task (trained group), or trained on a non-auditory change detection task (control group). On Day 2, all participants were tested on the flicker task while EEG was recorded. The trained group showed greater change detection accuracy than the control group. They were less biased to respond "same" and showed full generalization of learning from trained to novel auditory objects. ERPs for "change" compared to "same" trials showed more negative going P1, N1, and P2 amplitudes, as well as a larger P3b amplitude. The P3b amplitude also differed between the trained and control group, with larger amplitudes for the trained group. Analysis of ERPs to scenes viewed prior to a decision revealed build-up of a difference between "change" and "same" trials in N1 and P2. Results demonstrate that training has an impact early in the "same" versus "change" decision-making process, and that the flicker paradigm combined with the ERP method can be used to study the build-up of change detection in auditory scenes.

Attentional control in middle childhood is highly dynamic-Strong initial distraction is followed by advanced attention control

The ability to shield against distraction while focusing on a task requires the operation of executive functions and is essential for successful learning. We investigated the short-term dynamics of distraction control in a data set of 269 children aged 4-10 years and 51 adults pooled from three studies using multilevel models. Participants performed a visual categorization task while a task-irrelevant sequence of sounds was presented which consisted of frequently repeated standard sounds and rarely interspersed novel sounds. On average, participants responded slower in the categorization task after novel sounds. This distraction effect was more pronounced in children. Throughout the experiment, the initially strong distraction effects declined to the level of adults in the groups of 6- to 10-year-olds. Such a decline was neither observed in the groups of the 4- and 5-year-olds, who consistently showed a high level of distraction, nor in adults, who showed a constantly low level of distraction throughout the experimental session. Results indicate that distraction control is a highly dynamic process that qualitatively and quantitatively differs between age groups. We conclude that the analysis of short-term dynamics provides valuable insights into the development of attention control and might explain inconsistent findings regarding distraction control in middle childhood. In addition, models of attention control need to be refined to account for age-dependent rapid learning mechanisms. Our findings have implications for the design of learning situations and provide an additional source of information for the diagnosis and treatment of children with attention deficit disorders.

Neural responses to sensory novelty with and without conscious access

Detection of novel stimuli that violate statistical regularities in the sensory scene is of paramount importance for the survival of biological organisms. Event-related potentials, phasic increases in pupil size, and evoked changes in oscillatory power have been proposed as markers of sensory novelty detection. However, how conscious access to novelty modulates these different brain responses is not well understood. Here, we studied the neural responses to sensory novelty in the auditory modality with and without conscious access. We identified individual thresholds for conscious auditory discrimination and presented to our participants sequences of tones, where the last stimulus could be another standard, a subthreshold target or a suprathreshold target. Participants were instructed to report whether the last tone of each sequence was the same or different from those preceding it. Results indicate that attentional orientation to behaviorally relevant stimuli and overt decision-making mechanisms, indexed by the P3 event-related response and reaction times, best predict whether a novel stimulus will be consciously accessed. Theta power and pupil size do not predict conscious access to novelty, but instead reflect information maintenance and unexpected sensory uncertainty. These results highlight the interplay between bottom-up and top-down mechanisms and how the brain weights neural responses to novelty and uncertainty during perception and goal-directed behavior.

Auditory event-related potentials in separating patients with depressive disorders and non-depressed controls: A narrative review

This narrative review brings together the findings regarding the differences in the auditory event-related potentials (ERPs) between patients with depressive disorder and non-depressed control subjects. These studies' results can inform us of the possible alterations in sensory-cognitive processing in depressive disorders and the potential of using these ERPs in clinical applications. Auditory P3, mismatch negativity (MMN) and loudness dependence of auditory evoked potentials (LDAEP) were the subjects of the investigation. A search in PubMed yielded 84 studies. The findings of the reviewed studies were not highly consistent, but some patterns could be identified. For auditory P3b, the common findings were attenuated amplitude and prolonged latency among depressed patients. Regarding auditory MMN, especially the amplitude of duration deviance MMN was commonly attenuated, and the amplitude of frequency deviance MMN was increased in depressed patients. In LDAEP studies, generally, no differences between depressed patients and non-depressed controls were reported, although some group differences concerning specific depression subtypes were found. This review posits that future research should investigate whether certain stimulus conditions are particularly efficient at separating depressed and non-depressed participant groups. Future studies should contrast responses in different subpopulations of depressed patients, as well as different clinical groups (e.g., depressive disorder and anxiety disorder patients), to investigate the specificity of the auditory ERP alterations for depressive disorders.

Modeling Distraction: How Stimulus-driven Attention Capture Influences Goal-directed Behavior

The importance of paying attention to a task at hand is emphasized from an early age and extends throughout life. The costs of attentional focus, however, include the potential to miss important changes in the environment, so some process for monitoring nontask information is essential. In this study, a model of latent cognitive variables was applied to data obtained from a two-alternative forced-choice task where participants identified the longer of two sounds. Using an adaptive procedure task, accuracy was maintained at a higher or lower level creating two difficulties, and the sounds were heard either where frequency changes in the sound were rare or common (oddball and multistandard conditions, respectively). Frequency changes created stimulus-driven "distraction" effects in the oddball sequence only, and cognitive modeling (using the linear ballistic accumulator) attributed these effects to slowed accumulation of evidence about tone length on these trials. Concurrent recording of auditory ERPs revealed these delays in evidence accumulation to be related to the amplitude of N2 or mismatch negativity period and P300 response components. In contrast, the response time on trials after a rare frequency change was associated with increased caution in decision-making. Results support the utility of mapping behavioral and ERP measures of performance to latent cognitive processes that contribute to performance and are consistent with a momentary diversion of resources to evaluate the deviant sound feature and remodel predictions about sound.

Action effect predictions in 'what', 'when', and 'whether' intentional actions

It has been proposed that intentional action can be separated into three major types depending on the nature of the action choice - what (selecting what to do), when (selecting when to act) and whether (to perform the action or not). While many theories on action control assume that intentional action involves the prediction of action effects, there has not been any attempt to compare the three types of intentional actions (what, when, whether) with respect to action-effect prediction. Here, we employ an action-effect prediction paradigm where participants select the action on every trial based on either the what (choosing between alternative actions), when (choosing to respond at different time points) or whether (choosing to perform an action or not) action components, and each action choice is followed by either a predicted (standard) or a mispredicted (deviant) tone. We found a significant P2 difference between standard/deviant tones reflecting the formation of action-effect predictions regardless of whether the action choice was based on the 'what', 'when' or 'whether' decision. Furthermore, our analysis revealed that this P2 difference for the prediction effect was not observable in non-action trials within the 'whether' condition, which suggests an action-specific prediction process.

Electrophysiological correlates of stuttering severity: An ERP study

Although a variety of theories have been proposed to explain the etiology of stuttering, the exact neurological origin of it is still uncertain. The aim of this study is to investigate the correlation between stuttering severity and ERP measures. The population of this study consisted of 12 adults with moderate, 12 adults with severe stuttering, and 12 fluent speakers as the control group. ERPs were recorded during an auditory task in which subjects should determine an oddball stimulus. The result of mismatch negativity (MMN) amplitude analysis revealed significant differences between severe stuttering and fluent speakers groups and between two stuttering groups. Moreover, the result showed significant differences between the three study groups for P300 amplitude. The findings of the present study suggest that the differences in ERP components are existed not only between people who stutter and fluent speakers but also between people with different levels of stuttering severity.

Auditory mismatch responses are differentially sensitive to changes in muscarinic acetylcholine versus dopamine receptor function

The auditory mismatch negativity (MMN) has been proposed as a biomarker of NMDA receptor (NMDAR) dysfunction in schizophrenia. Such dysfunction may be caused by aberrant interactions of different neuromodulators with NMDARs, which could explain clinical heterogeneity among patients. In two studies (N = 81 each), we used a double-blind placebo-controlled between-subject design to systematically test whether auditory mismatch responses under varying levels of environmental stability are sensitive to diminishing and enhancing cholinergic vs. dopaminergic function. We found a significant drug × mismatch interaction: while the muscarinic acetylcholine receptor antagonist biperiden delayed and topographically shifted mismatch responses, particularly during high stability, this effect could not be detected for amisulpride, a dopamine D2/D3 receptor antagonist. Neither galantamine nor levodopa, which elevate acetylcholine and dopamine levels, respectively, exerted significant effects on MMN. This differential MMN sensitivity to muscarinic versus dopaminergic receptor function may prove useful for developing tests that predict individual treatment responses in schizophrenia.

The sound of silence: Predictive error responses to unexpected sound omission in adults

The human auditory system excels at detecting patterns needed for processing speech and music. According to predictive coding, the brain predicts incoming sounds, compares predictions to sensory input, and generates a prediction error whenever a mismatch between the prediction and sensory input occurs. Predictive coding can be indexed in EEG with the mismatch negativity (MMN) and P3a components, two ERP components that are elicited by infrequent deviant sounds (e.g., differing in pitch, duration, loudness) in a stream of frequent sounds. If these components reflect prediction error, they should also be elicited by omitting an expected sound, but few studies have examined this. We compared ERPs elicited by infrequent randomly occurring omissions (unexpected silences) in tone sequences presented at 2 tones/sec to ERPs elicited by frequent, regularly occurring omissions (expected silences) within a sequence of tones and resting state EEG (a constant silence). We found that unexpected silences elicited significant MMN and P3a, although the magnitude of these components was quite small and variable. These results provide evidence for hierarchical predictive coding, indicating that the brain predicts silences as well as sounds.

A cognitive model of response omissions in distraction paradigms

The effects of distraction on responses manifest in three ways: prolonged reaction times, and increased error and response omission rates. However, the latter effect is often ignored or assumed to be due to a separate cognitive process. We investigated omissions occurring in two paradigms that manipulated distraction. One required simple stimulus detection of younger participants, the second required choice responses and was completed by both younger and older participants. We fit data from these paradigms with a model that identifies three causes of omissions: two are related to the process of accumulating the evidence on which a response is based: intrinsic omissions (due to between-trial variation in accumulation rates making it impossible to ever reach the evidence threshold) and design omissions (due to response windows that cause slow responses not to be recorded; a third, contaminant omissions, allows for a cause unrelated to the response process. In both data sets systematic differences in omission rates across conditions were accounted for by task-related omissions. Intrinsic omissions played a lesser role than design omissions, even though the presence of design omissions was not evident in descriptive analyses of the data. The model provided an accurate account of all aspects of the detection data and the choice-response data, but slightly underestimated overall omissions in the choice paradigm, particularly in older participants, suggesting that further investigation of contaminant omission effects is needed.

How does self name influence the neural processing of emotional prosody? An ERP study

In this study, we investigated whether self-relevant information can accelerate the processing of emotional information. Our experiment, based on a passive auditory oddball paradigm, involved recording electroencephalography while participants listened to stimuli comprising their own names (ONs) and unfamiliar names (UNs) spoken with varying emotional prosody. At 220-300 ms, mismatch negativity (MMN) was more negative for ONs and angry prosody than for UNs and neutral prosody, respectively. These results suggest that attention is involuntarily attracted by ONs and emotional prosody, and that both types of information are given priority processing, even under pre-attentive conditions. Importantly, ONs with angry prosody induced more negative MMN than did similar UNs and ONs with neutral prosody, which indicates that the motivational significance embedded in angry prosody promotes the self-reference effect and, thus, involves more attention resources. At 300-500 ms, ONs triggered smaller P3a than did UNs, suggesting that less cognitive resources are required to process self-relevant information. These results suggest that self-relevant and emotional information of preferential processing interact with each other during the pre-attentive stage, with self-reference enhancing the processing of emotional information.

ERP signatures of auditory awareness in cross-modal distractor-induced deafness

Previous research showed that dual-task processes such as the attentional blink are not always transferable from unimodal to cross-modal settings. This study investigated whether such a transfer can be stated for a distractor-induced impairment of target detection established in vision (distractor-induced blindness, DIB) and recently observed in the auditory modality (distractor-induced deafness, DID). A cross-modal DID effect was confirmed: The detection of an auditory target indicated by a visual cue was impaired if multiple auditory distractors preceded the target. Event-related potentials (ERPs) were used to identify psychophysiological correlates of target detection. A frontal negativity about 200 ms succeeded by a sustained, widespread negativity was associated with auditory target awareness. In contrast to unimodal findings, P3 amplitude was not enhanced for hits. The results support the notion that early frontal attentional processes are linked to auditory awareness, whereas the P3 does not seem to be a reliable indicator of target access.

EEG and behavioral correlates of attentional processing while walking and navigating naturalistic environments

The capacity to regulate one's attention in accordance with fluctuating task demands and environmental contexts is an essential feature of adaptive behavior. Although the electrophysiological correlates of attentional processing have been extensively studied in the laboratory, relatively little is known about the way they unfold under more variable, ecologically-valid conditions. Accordingly, this study employed a 'real-world' EEG design to investigate how attentional processing varies under increasing cognitive, motor, and environmental demands. Forty-four participants were exposed to an auditory oddball task while (1) sitting in a quiet room inside the lab, (2) walking around a sports field, and (3) wayfinding across a university campus. In each condition, participants were instructed to either count or ignore oddball stimuli. While behavioral performance was similar across the lab and field conditions, oddball count accuracy was significantly reduced in the campus condition. Moreover, event-related potential components (mismatch negativity and P3) elicited in both 'real-world' settings differed significantly from those obtained under laboratory conditions. These findings demonstrate the impact of environmental factors on attentional processing during simultaneously-performed motor and cognitive tasks, highlighting the value of incorporating dynamic and unpredictable contexts within naturalistic designs.

Event-related potentials evidence for long-term audiovisual representations of phonemes in adults

The presence of long-term auditory representations for phonemes has been well-established. However, since speech perception is typically audiovisual, we hypothesized that long-term phoneme representations may also contain information on speakers' mouth shape during articulation. We used an audiovisual oddball paradigm in which, on each trial, participants saw a face and heard one of two vowels. One vowel occurred frequently (standard), while another occurred rarely (deviant). In one condition (neutral), the face had a closed, non-articulating mouth. In the other condition (audiovisual violation), the mouth shape matched the frequent vowel. Although in both conditions stimuli were audiovisual, we hypothesized that identical auditory changes would be perceived differently by participants. Namely, in the neutral condition, deviants violated only the audiovisual pattern specific to each block. By contrast, in the audiovisual violation condition, deviants additionally violated long-term representations for how a speaker's mouth looks during articulation. We compared the amplitude of mismatch negativity (MMN) and P3 components elicited by deviants in the two conditions. The MMN extended posteriorly over temporal and occipital sites even though deviants contained no visual changes, suggesting that deviants were perceived as interruptions in audiovisual, rather than auditory only, sequences. As predicted, deviants elicited larger MMN and P3 in the audiovisual violation compared to the neutral condition. The results suggest that long-term representations of phonemes are indeed audiovisual.

Attentional Modulation of Hierarchical Speech Representations in a Multitalker Environment

Humans are remarkably adept in listening to a desired speaker in a crowded environment, while filtering out nontarget speakers in the background. Attention is key to solving this difficult cocktail-party task, yet a detailed characterization of attentional effects on speech representations is lacking. It remains unclear across what levels of speech features and how much attentional modulation occurs in each brain area during the cocktail-party task. To address these questions, we recorded whole-brain blood-oxygen-level-dependent (BOLD) responses while subjects either passively listened to single-speaker stories, or selectively attended to a male or a female speaker in temporally overlaid stories in separate experiments. Spectral, articulatory, and semantic models of the natural stories were constructed. Intrinsic selectivity profiles were identified via voxelwise models fit to passive listening responses. Attentional modulations were then quantified based on model predictions for attended and unattended stories in the cocktail-party task. We find that attention causes broad modulations at multiple levels of speech representations while growing stronger toward later stages of processing, and that unattended speech is represented up to the semantic level in parabelt auditory cortex. These results provide insights on attentional mechanisms that underlie the ability to selectively listen to a desired speaker in noisy multispeaker environments.

Shorter Contextual Timescale Rather Than Memory Deficit in Aging

Many aspects of cognitive ability and brain function that change as we age look like deficits on account of measurable differences in comparison to younger adult groups. One such difference occurs in auditory sensory responses that index perceptual learning. Meta-analytic findings show reliable age-related differences in auditory responses to repetitive patterns of sound and to rare violations of those patterns, variously attributed to deficits in auditory sensory memory and inhibition. Here, we determine whether proposed deficits would render older adults less prone to primacy effects, robustly observed in young adults, which present as a tendency for first learning to have a disproportionate influence over later perceptual inference. The results confirm this reduced sensitivity to primacy effects but do not support impairment in auditory sensory memory as the origin of this difference. Instead, the aging brain produces data consistent with shorter timescales of contextual reference. In conclusion, age-related differences observed previously for perceptual inference appear highly context-specific necessitating reconsideration of whether and to what function the notion of deficit should be attributed, and even whether the notion of deficit is appropriate at all.

Somatosensory Deviance Detection ERPs and Their Relationship to Analogous Auditory ERPs and Interoceptive Accuracy

Abstract. Automatic deviance detection has been widely explored in terms of mismatch responses (mismatch negativity or mismatch response) and P3a components of event-related potentials (ERPs) under a predictive coding framework; however, the somatosensory mismatch response has been investigated less often regarding the different types of changes than its auditory counterpart. It is not known whether the deviance detection responses from different modalities correlate, reflecting a general prediction error mechanism of the central nervous system. Furthermore, interoceptive functions have been associated with predictive coding theory, but whether interoceptive accuracy correlates with deviance detection brain responses has rarely been investigated. Here, we measured ERPs to changes in somatosensory stimuli’s location and intensity and in sound intensity in healthy adults ( n = 34). Interoceptive accuracy was measured with a heartbeat discrimination task, where participants indicated whether their heartbeats were simultaneous or non-simultaneous with sound stimuli. We found a mismatch response and a P3a response to somatosensory location and auditory intensity changes, but for somatosensory intensity changes, only a P3a response was found. Unexpectedly, there were neither correlations between the somatosensory location deviance and intensity deviance brain responses nor between auditory and somatosensory brain responses. In addition, the brain responses did not correlate with interoceptive accuracy. The results suggest that although deviance detection in the auditory and somatosensory modalities are likely based on similar neural mechanisms at a cellular level, their ERP indexes do not indicate a linear association in sensitivity for deviance detection between the modalities. Furthermore, although sensory deviance detection and interoceptive detection are both associated with predictive coding functions, under these experimental settings, functional relationships were not observed. These results should be taken into account in the future development of theories related to human sensory functions and in extensions of the predictive coding theory in particular.

Altered mismatch response of inferior parietal lobule in amnestic mild cognitive impairment: A magnetoencephalographic study

Background

Mismatch negativity (MMN) reflects the functional integrity of sensory memory function. With the advantages of independence of individual's focused attention and behavioral cooperation, this neurophysiological signal is particularly suitable for investigating elderly with cognitive decline such as amnestic mild cognitive impairment (aMCI). However, the existing results remain substantially inconsistent whether these patients show deficits of MMN. In order to reconcile the previous disputes, the present study used magnetoencephalography combined with distributed source imaging methods to determine the source‐level magnetic mismatch negativity (MMNm) in aMCI.

Methods

A total of 26 healthy controls (HC) and 26 patients with aMCI underwent an auditory oddball paradigm during the MEG recordings. MMNm amplitudes and latencies in the bilateral superior temporal gyrus, inferior frontal gyrus, and inferior parietal lobule (IPL) were compared between HC and aMCI groups. The correlations of MMNm responses with performance of auditory/verbal memory tests were examined. Finally, MMNm and its combination with verbal/auditory memory tests were submitted to receiver operating characteristic (ROC) curve analysis.

Results

Compared to HC, patients with aMCI showed significantly delayed MMNm latencies in the IPL. Among the patients with aMCI, longer MMNm latencies of left IPL were associated with lower scores of Chinese Version Verbal Learning Test (CVVLT). The ROC curve analysis revealed that the combination of MMNm latencies of left IPL and CVVLT scores yielded a moderate accuracy in the discrimination of aMCI from HC at an individual level.

Conclusions

Our data suggest dysfunctional MMNm in patients with aMCI, particularly in the IPL.

Using electrophysiological measures to evaluate the sense of presence in immersive virtual environments: An event-related potential study

Sense of presence has been often explored in the context of virtual reality (VR) and immersive visual technologies; however, standardized and objective measures of the sense of presence have been difficult to find. Studies attempting to find physiological correlates of sense presence using electroencephalography (EEG) have reported mixed results. In the present study, we used brain event-related potentials (ERPs) elicited by auditory stimuli to identify an objective physiological index of sense of presence during VR, attempting to replicate the findings of previous studies and explain the heterogeneity of results reported in the literature. Participants in our experiment were asked to experience an immersive virtual environment using a modern head-mounted display while passively hearing task-irrelevant frequent standard and infrequent deviant tones as in a classic auditory oddball paradigm. Subsequently, they were asked to complete a battery of questionnaires aimed to estimate their sense of presence during the VR. EEG and questionnaire data from three-seventh participants were analyzed. ERP components evoked by the auditory stimuli were then analyzed. Late ERP components (after 450 ms from stimulus onset) registered over central brain areas were associated with the sense of presence as measured with questionnaires, while earlier components were not associated with presence. The use of different questionnaires and the content of the VR environment may both be a plausible explanation for heterogeneous results as reported in previous studies. The present study showed that late ERP components recorded over the central brain may represent good electrophysiological correlates of the subjective sense of presence.

Short-Term Audiovisual Spatial Training Enhances Electrophysiological Correlates of Auditory Selective Spatial Attention

Audiovisual cross-modal training has been proposed as a tool to improve human spatial hearing. Here, we investigated training-induced modulations of event-related potential (ERP) components that have been associated with processes of auditory selective spatial attention when a speaker of interest has to be localized in a multiple speaker ("cocktail-party") scenario. Forty-five healthy participants were tested, including younger (19-29 years; n = 21) and older (66-76 years; n = 24) age groups. Three conditions of short-term training (duration 15 min) were compared, requiring localization of non-speech targets under "cocktail-party" conditions with either (1) synchronous presentation of co-localized auditory-target and visual stimuli (audiovisual-congruency training) or (2) immediate visual feedback on correct or incorrect localization responses (visual-feedback training), or (3) presentation of spatially incongruent auditory-target and visual stimuli presented at random positions with synchronous onset (control condition). Prior to and after training, participants were tested in an auditory spatial attention task (15 min), requiring localization of a predefined spoken word out of three distractor words, which were presented with synchronous stimulus onset from different positions. Peaks of ERP components were analyzed with a specific focus on the N2, which is known to be a correlate of auditory selective spatial attention. N2 amplitudes were significantly larger after audiovisual-congruency training compared with the remaining training conditions for younger, but not older, participants. Also, at the time of the N2, distributed source analysis revealed an enhancement of neural activity induced by audiovisual-congruency training in dorsolateral prefrontal cortex (Brodmann area 9) for the younger group. These findings suggest that cross-modal processes induced by audiovisual-congruency training under "cocktail-party" conditions at a short time scale resulted in an enhancement of correlates of auditory selective spatial attention.

Isoflurane effects on the N1 and other long-latency auditory evoked potentials in Wistar rats

Long-latency auditory evoked potentials (LLAEPs) may help further advances in understanding consciousness under general anesthesia and promote more objective means of assessing sedation depth than conventional clinical signs. Among the LLAEP components, the auditory N1 shows promise as a measure of sedation depth and a marker of consciousness, but findings are so far inconclusive. Research with animals can help elucidate the effects of various anesthetics on the N1 and other LLAEPs, but investigations of LLAEPs under anesthesia in animals is lacking. To address this deficit, we examined the P1, N1, P2, and N2, along with their corresponding peak-to-peak complexes, in 10 Wistar rats anesthetized with 1.5-2 % isoflurane in pure oxygen and again after recovery. While under anesthesia, subdermal needle electrodes were inserted and secured for electroencephalographic (EEG) recordings. LLAEPs were assessed during a 20-min, passive, two-tone (500 ms inter-tone interval) paradigm with randomized short (1 s) and long (5 s) inter-pair intervals (IPIs). Overall, while the LLAEP peaks under isoflurane were less defined, they were not eliminated. The peak-to-peak amplitudes, particularly the P1-N1, were significantly smaller under isoflurane than during post-recovery. Our preliminary findings indicate that isoflurane produces global suppression across LLAEP components, presumably reflecting impaired integration of top-down and bottom-up attention and sensory systems under profound sedation with isoflurane.

Perceptual awareness negativity: a physiological correlate of sensory consciousness

Much research on the neural correlates of consciousness (NCC) has focused on two evoked potentials, the P3b and the visual or auditory awareness negativity (VAN, AAN). Surveying a broad range of recent experimental evidence, we find that repeated failures to observe the P3b during conscious perception eliminate it as a putative NCC. Neither the VAN nor the AAN have been dissociated from consciousness; furthermore, a similar neural signal correlates with tactile consciousness. These awareness negativities can be maximal contralateral to the evoking stimulus, are likely generated in underlying sensory cortices, and point to the existence of a generalized perceptual awareness negativity (PAN) reflecting the onset of sensory consciousness.

Does sonification of action simulation training impact corticospinal excitability and audiomotor plasticity?

Sonification is a sensory augmentation strategy whereby a sound is associated with, and modulated by, movement. Evidence suggests that sonification could be a viable strategy to maximize learning and rehabilitation. Recent studies investigated sonification of action observation, reporting beneficial effects, especially in Parkinson's disease. However, research on simulation training-a training regime based on action observation and motor imagery, in which actions are internally simulated, without physical execution-suggest that action observation alone is suboptimal, compared to the combined use of action observation and motor imagery. In this study, we explored the effects of sonified action observation and motor imagery on corticospinal excitability, as well as to evaluate the extent of practice-dependent plasticity induced by this training. Nineteen participants were recruited to complete a practice session based on combined and congruent action observation and motor imagery (AOMI) and physical imitation of the same action. Prior to the beginning, participants were randomly assigned to one of two groups, one group (nine participants) completed the practice block with sonified AOMI, while the other group (ten participants) completed the practice without extrinsic auditory information and served as control group. To investigate practice-induced plasticity, participants completed two auditory paired associative stimulation (aPAS) protocols, one completed after the practice block, and another one completed alone, without additional interventions, at least 7 days before the practice. After the practice block, both groups significantly increased their corticospinal excitability, but sonification did not exert additional benefits, compared to non-sonified conditions. In addition, aPAS significantly increased corticospinal excitability when completed alone, but when it was primed by a practice block, no modulatory effects on corticospinal excitability were found. It is possible that sonification of combined action observation and motor imagery may not be a useful strategy to improve corticospinal, but further studies are needed to explore its relationship with performance improvements. We also confirm the neuromodulatory effect of aPAS, but its interaction with audiomotor practice remain unclear.

Impaired Audiovisual Representation of Phonemes in Children with Developmental Language Disorder

We examined whether children with developmental language disorder (DLD) differed from their peers with typical development (TD) in the degree to which they encode information about a talker’s mouth shape into long-term phonemic representations. Children watched a talker’s face and listened to rare changes from [i] to [u] or the reverse. In the neutral condition, the talker’s face had a closed mouth throughout. In the audiovisual violation condition, the mouth shape always matched the frequent vowel, even when the rare vowel was played. We hypothesized that in the neutral condition no long-term audiovisual memory traces for speech sounds would be activated. Therefore, the neural response elicited by deviants would reflect only a violation of the observed audiovisual sequence. In contrast, we expected that in the audiovisual violation condition, a long-term memory trace for the speech sound/lip configuration typical for the frequent vowel would be activated. In this condition then, the neural response elicited by rare sound changes would reflect a violation of not only observed audiovisual patterns but also of a long-term memory representation for how a given vowel looks when articulated. Children pressed a response button whenever they saw a talker’s face assume a silly expression. We found that in children with TD, rare auditory changes produced a significant mismatch negativity (MMN) event-related potential (ERP) component over the posterior scalp in the audiovisual violation condition but not in the neutral condition. In children with DLD, no MMN was present in either condition. Rare vowel changes elicited a significant P3 in both groups and conditions, indicating that all children noticed auditory changes. Our results suggest that children with TD, but not children with DLD, incorporate visual information into long-term phonemic representations and detect violations in audiovisual phonemic congruency even when they perform a task that is unrelated to phonemic processing.

Deficits in Processing of Lexical Tones in Mandarin-Speaking Children With Developmental Language Disorder: Electrophysiological Evidence

Purpose This study explored the neural marker indexing deficits in discriminating lexical tone changes in Mandarin-speaking children with developmental language disorders (DLDs) using mismatch negativity, an event-related potential component for auditory change detection. Mandarin has four lexical tones characterized by a high-level tone (T1), high-rising tone (T2), low-dipping tone (T3), and high-falling tone (T4), in which the T2/T3 contrast is acoustically less discriminable in developmental groups. Therefore, this study further examined how deficits in children with DLD would vary with tonal contrasts' acoustic saliency. Method Event-related potentials were measured using the multideviant oddball paradigm described by Lee et al. (2012), who used Mandarin syllables [i] in T3 as the standard sound (80%), T1 as the large deviant (10%), and T2 as the small deviant (10%). Twelve children with DLD aged between 4 and 6 years participated in this study, and 12 age-matched children with typical development were selected from the data set of Lee et al. (2012) as the controls. Results The T1/T3 change elicited adultlike mismatch negativity in both the DLD and control groups, while no group difference was revealed. The T2/T3 change elicited a robust positive mismatch response (P-MMR) in children with DLD, while the P-MMR was less significant in the control group. The group comparisons revealed a larger P-MMR in children with DLD than in the control group. Furthermore, children with lower scores in language assessments tend to reveal larger P-MMRs. Conclusions This study demonstrated that deficits in children with DLD in discriminating subtle lexical tone changes reflect greater positivity of P-MMR to T2/T3 change. This implies that MMR to T2/T3 may serve as a neural marker for evaluating language delay in preschoolers.

Neural Representation of the English Vowel Feature [High]: Evidence From /ε/ vs. /ɪ/

Many studies have observed modulation of the amplitude of the neural index mismatch negativity (MMN) related to which member of a phoneme contrast [phoneme A, phoneme B] serves as the frequent (standard) and which serves as the infrequent (deviant) stimulus (i.e., AAAB vs. BBBA) in an oddball paradigm. Explanations for this amplitude modulation range from acoustic to linguistic factors. We tested whether exchanging the role of the mid vowel /ε/ vs. high vowel /ɪ/ of English modulated MMN amplitude and whether the pattern of modulation was compatible with an underspecification account, in which the underspecified height values are [−high] and [−low]. MMN was larger for /ε/ as the deviant, but only when compared across conditions to itself as the standard. For the within-condition comparison, MMN was larger to /ɪ/ deviant minus /ε/ standard than to the reverse. A condition order effect was also observed. MMN amplitude was smaller to the deviant stimulus if it had previously served as the standard. In addition, the amplitudes of late discriminative negativity (LDN) showed similar asymmetry. LDN was larger for deviant /ε/ than deviant /ɪ/ when compared to themselves as the standard. These findings were compatible with an underspecification account, but also with other accounts, such as the Natural Referent Vowel model and a prototype model; we also suggest that non-linguistic factors need to be carefully considered as additional sources of speech processing asymmetries.

No Evidence That Cognitive and Physical Activities Are Related to Changes in EEG Markers of Cognition in Older Adults at Risk of Dementia

An active lifestyle as well as cognitive and physical training (PT) may benefit cognition by increasing cognitive reserve, but the underlying neurobiological mechanisms of this reserve capacity are not well understood. To investigate these mechanisms of cognitive reserve, we focused on electrophysiological correlates of cognitive performance, namely on an event-related measure of auditory memory and on a measure of global coherence. Both measures have shown to be sensitive markers for cognition and might therefore be suitable to investigate potential training- and lifestyle-related changes. Here, we report on the results of an electrophysiological sub-study that correspond to previously published behavioral findings. Altogether, 65 older adults with subjective or objective cognitive impairment and aged 60-88 years were assigned to a 10-week cognitive (n = 19) or a 10-week PT (n = 21) or to a passive control group (n = 25). In addition, self-reported lifestyle was assessed at baseline. We did not find an effect of both training groups on electroencephalography (EEG) measures of auditory memory decay or global coherence (ps ≥ 0.29) and a more active lifestyle was not associated with improved global coherence (p = 0.38). Results suggest that a 10-week unimodal cognitive or PT and an active lifestyle in older adults at risk for dementia are not strongly related to improvements in electrophysiological correlates of cognition.

Mismatch Negativity and Stimulus-Preceding Negativity in Paradigms of Increasing Auditory Complexity: A Possible Role in Predictive Coding

The auditory mismatch negativity (MMN) has been considered a preattentive index of auditory processing and/or a signature of prediction error computation. This study tries to demonstrate the presence of an MMN to deviant trials included in complex auditory stimuli sequences, and its possible relationship to predictive coding. Additionally, the transfer of information between trials is expected to be represented by stimulus-preceding negativity (SPN), which would possibly fit the predictive coding framework. To accomplish these objectives, the EEG of 31 subjects was recorded during an auditory paradigm in which trials composed of stimulus sequences with increasing or decreasing frequencies were intermingled with deviant trials presenting an unexpected ending. Our results showed the presence of an MMN in response to deviant trials. An SPN appeared during the intertrial interval and its amplitude was reduced in response to deviant trials. The presence of an MMN in complex sequences of sounds and the generation of an SPN component, with different amplitudes in deviant and standard trials, would support the predictive coding framework.

Automatic detection of peripheral stimuli in shooters and handball players: an event-related potential study

This study examined the practice-related sensitivity of automatic change detection. The visual mismatch negativity (vMMN) component of event-related potentials was compared in handball players and in sport shooters. Whereas effective performance in handball requires processing of a wide visual field, effective performance in shooting requires concentration to a narrow field. Thus, we hypothesized larger sensitivity to peripheral stimuli violating the regularity of sequential stimulation in handball players. Participants performed a tracking task, while task-irrelevant checkerboard patterns (a frequent and an infrequent type) were presented in the lateral parts of the visual field. We analyzed the vMMN, a signature of automatic detection of violating sequential regularity, and sensory components (P1, N1, and P2). We obtained larger vMMN in the handball players' group indicating larger sensitivity to peripheral stimuli. These results suggest the plasticity of the automatic visual processing, i.e., it can adapt to sport-specific demands, and this can be captured even in a short experimental session in the laboratory.

Central Auditory Tests to Track Cognitive Function in People With HIV: Longitudinal Cohort Study

Background

The development of neurocognitive deficits in people infected with HIV is a significant public health problem. Previous cross-sectional studies have shown that performance on central auditory tests (CATs) correlates with cognitive test results in those with HIV, but no longitudinal data exist for confirmation. We have been performing longitudinal assessments of central auditory and cognitive function on a cohort of HIV-positive and HIV-negative individuals in Dar es Salaam, Tanzania to understand how the central auditory system could be used to study and track the progress of central nervous system dysfunction.

Objective

The goal of the project was to determine if CATs can track the trajectory of cognitive function over time in people diagnosed with HIV.

Methods

Tests of peripheral and central auditory function as well as cognitive performance were performed on 382 individuals over the course of 3.5 years. Visits were scheduled every 6 months. CATs included tests of auditory temporal processing (gap detection) and speech perception in noise (Hearing in Noise Test and Triple Digit Test). Cognitive tests included the Montreal Cognitive Assessment (MoCA), Test of Variables of Attention (TOVA), and subtests from the Cogstate battery. HIV-positive subjects were divided into groups based on their CAT results at their final visit (bottom 20%, top 20%, middle 60%). Primary analyses focused on the comparison between HIV-positive individuals that performed worse on CATs (bottom 20%) and the overall HIV-positive group (middle 60%). Data were analyzed using linear mixed-effect models with time as the main fixed effect.

Results

The group with the worst (bottom 20%) CAT performance showed a difference in trajectory for the MoCA (P=.003), TOVA (P<.048), and Cogstate (P<.046) over the course of the study period compared to the overall HIV-positive group. A battery of three CATs showed a significant difference in cognitive trajectory over a relatively short study period of 3.5 years independent of age (bottom 20% vs HIV-positive group).

Conclusions

The results of this study support the ability for CATs to track cognitive function over time, suggesting that central auditory processing can provide a window into central nervous system performance. CATs can be simple to perform, and are relatively insensitive to education and socioeconomic status because they only require repeating sentences, numbers, or detecting gaps in noise. These tests could potentially provide a time-efficient, low-cost method to screen for and monitor cognitive decline in patients with HIV, making them a useful surveillance tool for this major public health problem.

Neural Mechanisms of Hearing Recovery for Cochlear-Implanted Patients: An Electroencephalogram Follow-Up Study

Background

Patients with severe profound hearing loss could benefit from cochlear implantation (CI). However, the neural mechanism of such benefit is still unclear. Therefore, we analyzed the electroencephalogram (EEG) and behavioral indicators of auditory function remodeling in patients with CI. Both indicators were sampled at multiple time points after implantation (1, 90, and 180 days).

Methods

First, the speech perception ability was evaluated with the recording of a list of Chinese words and sentences in 15 healthy controls (HC group) and 10 patients with CI (CI group). EEG data were collected using an oddball paradigm. Then, the characteristics of event-related potentials (ERPs) and mismatch negative (MMN) were compared between the CI group and the HC group. In addition, we analyzed the phase lag indices (PLI) in the CI group and the HC group and calculated the difference in functional connectivity between the two groups at different stages after implantation.

Results

The behavioral indicator, speech recognition ability, in CI patients improved as the implantation time increased. The MMN analysis showed that CI patients could recognize the difference between standard and deviation stimuli just like the HCs 90 days after cochlear implantation. Comparing the latencies of N1/P2/MMN between the CI group and the HC group, we found that the latency of N1/P2 in CI patients was longer, while the latency of MMN in CI users was shorter. In addition, PLI-based whole-brain functional connectivity (PLI-FC) showed that the difference between the CI group and the HC group mainly exists in electrode pairs between the bilateral auditory area and the frontal area. Furthermore, all those differences gradually decreased with the increase in implantation time.

Conclusion

The N1 amplitude, N1/P2/MMN latency, and PLI-FC in the alpha band may reflect the process of auditory function remodeling and could be an objective index for the assessment of speech perception ability and the effect of cochlear implantation.