Frequency discrimination at different frequency levels as indexed by electrophysiological and behavioral measures

Globally, songs and instrumental melodies are slower and higher and use more stable pitches than speech: A Registered Report

Both music and language are found in all known human societies, yet no studies have compared similarities and differences between song, speech, and instrumental music on a global scale. In this Registered Report, we analyzed two global datasets: (i) 300 annotated audio recordings representing matched sets of traditional songs, recited lyrics, conversational speech, and instrumental melodies from our 75 coauthors speaking 55 languages; and (ii) 418 previously published adult-directed song and speech recordings from 209 individuals speaking 16 languages. Of our six preregistered predictions, five were strongly supported: Relative to speech, songs use (i) higher pitch, (ii) slower temporal rate, and (iii) more stable pitches, while both songs and speech used similar (iv) pitch interval size and (v) timbral brightness. Exploratory analyses suggest that features vary along a "musi-linguistic" continuum when including instrumental melodies and recited lyrics. Our study provides strong empirical evidence of cross-cultural regularities in music and speech.

Order effects in task-free learning: Tuning to information-carrying sound features

Event-related potentials (ERPs) acquired during task-free passive listening can be used to study how sensitivity to common pattern repetitions and rare deviations changes over time. These changes are purported to represent the formation and accumulation of precision in internal models that anticipate future states based on probabilistic and/or statistical learning. This study features an unexpected finding; a strong order-dependence in the speed with which deviant responses are elicited that anchors to first learning. Participants heard four repetitions of a sequence in which an equal number of short (30 msec) and long (60 msec) pure tones were arranged into four blocks in which one was common (the standard, p = .875) and the other rare (the deviant, p = .125) with probabilities alternating across blocks. Some participants always heard the sequences commencing with the 30 msec deviant block, and others always with the 60 msec deviant block first. A deviance-detection component known as mismatch negativity (MMN) was extracted from responses and the point in time at which MMN reached maximum amplitude was used as the dependent variable. The results show that if participants heard sequences commencing with the 60 msec deviant block first, the MMN to the 60 msec and 30 msec deviant peaked at an equivalent latency. However, if participants heard sequences commencing with the 30 msec deviant first, the MMN peaked earlier to the 60 msec deviant. Furthermore, while the 30 msec MMN latency did not differ as a function of sequence composition, the 60 msec MMN latency did and was earlier when the sequences began with a 30 msec deviant first. By examining MMN latency effects as a function of age and hearing level it was apparent that the differentiation in 30 msec and 60 msec MMN latency expands with older age and raised hearing threshold due to prolongation of the time taken for the 30 msec MMN to peak. The observations are discussed with reference to how the initial sound composition may tune the auditory system to be more sensitive to different cues (i.e., offset responses vs perceived loudness). The order-effect demonstrates a remarkably powerful anchoring to first learning that might reflect initial tuning to the most valuable discriminating feature within a given listening environment, an effect that defies explanation based on statistical information alone.

Beat processing in newborn infants cannot be explained by statistical learning based on transition probabilities

Newborn infants have been shown to extract temporal regularities from sound sequences, both in the form of learning regular sequential properties, and extracting periodicity in the input, commonly referred to as a regular pulse or the 'beat'. However, these two types of regularities are often indistinguishable in isochronous sequences, as both statistical learning and beat perception can be elicited by the regular alternation of accented and unaccented sounds. Here, we manipulated the isochrony of sound sequences in order to disentangle statistical learning from beat perception in sleeping newborn infants in an EEG experiment, as previously done in adults and macaque monkeys. We used a binary accented sequence that induces a beat when presented with isochronous timing, but not when presented with randomly jittered timing. We compared mismatch responses to infrequent deviants falling on either accented or unaccented (i.e., odd and even) positions. Results showed a clear difference between metrical positions in the isochronous sequence, but not in the equivalent jittered sequence. This suggests that beat processing is present in newborns. Despite previous evidence for statistical learning in newborns the effects of this ability were not detected in the jittered condition. These results show that statistical learning by itself does not fully explain beat processing in newborn infants.

Probing Beat Perception with Event-Related Potentials (ERPs) in Human Adults, Newborns, and Nonhuman Primates

The aim of this chapter is to give an overview of how the perception of rhythmic temporal regularity such as a regular beat in music can be studied in human adults, human newborns, and nonhuman primates using event-related brain potentials (ERPs). First, we discuss different aspects of temporal structure in general, and musical rhythm in particular, and we discuss the possible mechanisms underlying the perception of regularity (e.g., a beat) in rhythm. Additionally, we highlight the importance of dissociating beat perception from the perception of other types of structure in rhythm, such as predictable sequences of temporal intervals, ordinal structure, and rhythmic grouping. In the second section of the chapter, we start with a discussion of auditory ERPs elicited by infrequent and frequent sounds: ERP responses to regularity violations, such as mismatch negativity (MMN), N2b, and P3, as well as early sensory responses to sounds, such as P1 and N1, have been shown to be instrumental in probing beat perception. Subsequently, we discuss how beat perception can be probed by comparing ERP responses to sounds in regular and irregular sequences, and by comparing ERP responses to sounds in different metrical positions in a rhythm, such as on and off the beat or on strong and weak beats. Finally, we will discuss previous research that has used the aforementioned ERPs and paradigms to study beat perception in human adults, human newborns, and nonhuman primates. In doing so, we consider the possible pitfalls and prospects of the technique, as well as future perspectives.

Dual task measures in older adults with and without cognitive impairment: response to simultaneous cognitive-exercise training and minimal clinically important difference estimates

BACKGROUND

Responsiveness and minimal clinically important difference (MCID) are critical indices to understand whether observed improvement represents a meaningful improvement after intervention. Although simultaneous cognitive-exercise training (SCET; e.g., performing memory tasks while cycling) has been suggested to enhance the cognitive function of older adults, responsiveness and MCID have not been established. Hence, we aimed to estimate responsiveness and MCIDs of two dual task performance involving cognition and hand function in older adults with and without cognitive impairment and to compare the differences in responsiveness and MCIDs of the two dual task performance between older adults with and without cognitive impairment.

METHODS

A total of 106 older adults completed the Montreal Cognitive Assessment and two dual tasks before and after SCET. One dual task was a combination of Serial Sevens Test and Box and Block Test (BBT), and the other included frequency discrimination and BBT. We used effect size and standardized response mean to indicate responsiveness and used anchor- and distribution-based approaches to estimating MCID ranges. When conducting data analysis, all participants were classified into two cognitive groups, cognitively healthy (Montreal Cognitive Assessment ≥ 26) and cognitively impaired (Montreal Cognitive Assessment < 26) groups, based on the scores of the Montreal Cognitive Assessment before SCET.

RESULTS

In the cognitively healthy group, Serial Seven Test performance when tasked with BBT and BBT performance when tasked with Serial Seven Test were responsive to SCET (effect size = 0.18-0.29; standardized response mean = 0.25-0.37). MCIDs of Serial Seven Test performance when tasked with BBT ranged 2.09-2.36, and MCIDs of BBT performance when tasked with Serial Seven Test ranged 3.77-5.85. In the cognitively impaired group, only frequency discrimination performance when tasked with BBT was responsive to SCET (effect size = 0.37; standardized response mean = 0.47). MCIDs of frequency discrimination performance when tasked with BBT ranged 1.47-2.18, and MCIDs of BBT performance when tasked with frequency discrimination ranged 1.13-7.62.

CONCLUSIONS

Current findings suggest that a change in Serial Seven Test performance when tasked with BBT between 2.09 and 2.36 corrected number (correct responses - incorrect responses) should be considered a meaningful change for older adults who are cognitively healthy, and a change in frequency discrimination performance when tasked with BBT between 1.47 and 2.18 corrected number (correct responses - incorrect responses) should be considered a meaningful change for older adults who are cognitively impaired. Clinical practitioners may use these established MCIDs of dual tasks involving cognition and hand function to interpret changes following SCET for older adults with and without cognitive impairment.

TRIAL REGISTRATION

NCT04689776, 30/12/2020.

Opposite effects of rapid auditory stimulation on tetanized and non-tetanized tone of adjacent frequency: Mismatch negativity study

Our study describes the effects of sensory tetanization on neurophysiological and behavioral measures in humans linking cellular studies of long-term potentiation with high-level brain processes. Rapid (every 75ms) presentation of pure tone (1020 Hz, 50ms) for 2 minutes was preceded and followed by oddball blocks that contained the same stimulus presented as deviant (probability of 5-10%) interspersed with standard (80-90%) and deviant tones (5-10%) of adjacent frequencies (1000 and 980Hz, respectively). Mismatch negativity (MMN) component in response to tetanized tone (1020Hz), while being similar to MMN for non-tetanized tone before tetanization, became larger than that after tetanization, pointing to the increase in cortical differentiation of these tones. However, this differentiation was partially due to the MMN decrease after tetanization for tones adjacent to tetanized frequency, suggesting the influence of lateral inhibition to this effect. Although MMN correlated with tone discriminability in a psychophysical task, the behavioral improvement after tetanization was not statistically detectable. To conclude, short-term auditory tetanization affects cortical representation of tones that are not limited to the tetanized stimuli.

Coloured hearing, colour music, colour organs, and the search for perceptually meaningful correspondences between colour and sound

There has long been interest in the nature of the relationship(s) between hue and pitch or, in other words, between colour and musical/pure tones, stretching back at least as far as Newton, Goethe, Helmholtz, and beyond. In this narrative historical review, we take a closer look at the motivations that have lain behind the various assertions that have been made in the literature concerning the analogies, and possible perceptual similarities, between colour and sound. During the last century, a number of experimental psychologists have also investigated the nature of the correspondence between these two primary dimensions of perceptual experience. The multitude of different crossmodal mappings that have been put forward over the centuries are summarized, and a distinction drawn between physical/structural and psychological correspondences. The latter being further sub-divided into perceptual and affective categories. Interest in physical correspondences has typically been motivated by the structural similarities (analogous mappings) between the organization of perceptible dimensions of auditory and visual experience. Emphasis has been placed both on the similarity in terms of the number of basic categories into which pitch and colour can be arranged and also on the fact that both can be conceptualized as circular dimensions. A distinction is drawn between those commentators who have argued for a dimensional alignment of pitch and hue (based on a structural mapping), and those who appear to have been motivated by the existence of specific correspondences between particular pairs of auditory and visual stimuli instead (often, as we will see, based on the idiosyncratic correspondences that have been reported by synaesthetes). Ultimately, though, the emotional-mediation account would currently appear to provide the most parsimonious account for whatever affinity the majority of people experience between musical sounds and colour.

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.

Arcuate fasciculus architecture is associated with individual differences in pre-attentive detection of unpredicted music changes

The mismatch negativity (MMN) is an event related brain potential (ERP) elicited by unpredicted sounds presented in a sequence of repeated auditory stimuli. The neural sources of the MMN have been previously attributed to a fronto-temporo-parietal network which crucially overlaps with the so-called auditory dorsal stream, involving inferior and middle frontal, inferior parietal, and superior and middle temporal regions. These cortical areas are structurally connected by the arcuate fasciculus (AF), a three-branch pathway supporting the feedback-feedforward loop involved in auditory-motor integration, auditory working memory, storage of acoustic templates, as well as comparison and update of those templates. Here, we characterized the individual differences in the white-matter macrostructural properties of the AF and explored their link to the electrophysiological marker of passive change detection gathered in a melodic multifeature MMN-EEG paradigm in 26 healthy young adults without musical training. Our results show that left fronto-temporal white-matter connectivity plays an important role in the pre-attentive detection of rhythm modulations within a melody. Previous studies have shown that this AF segment is also critical for language processing and learning. This strong coupling between structure and function in auditory change detection might be related to life-time linguistic (and possibly musical) exposure and experiences, as well as to timing processing specialization of the left auditory cortex. To the best of our knowledge, this is the first time in which the relationship between neurophysiological (EEG) and brain white-matter connectivity indexes using DTI-tractography are studied together. Thus, the present results, although still exploratory, add to the existing evidence on the importance of studying the constraints imposed on cognitive functions by the underlying structural connectivity.

Long-Term Musical Training Alters Auditory Cortical Activity to the Frequency Change

Objective: The ability to detect frequency variation is a fundamental skill necessary for speech perception. It is known that musical expertise is associated with a range of auditory perceptual skills, including discriminating frequency change, which suggests the neural encoding of spectral features can be enhanced by musical training. In this study, we measured auditory cortical responses to frequency change in musicians to examine the relationships between N1/P2 responses and behavioral performance/musical training. Methods: Behavioral and electrophysiological data were obtained from professional musicians and age-matched non-musician participants. Behavioral data included frequency discrimination detection thresholds for no threshold-equalizing noise (TEN), +5, 0, and -5 signal-to-noise ratio settings. Auditory-evoked responses were measured using a 64-channel electroencephalogram (EEG) system in response to frequency changes in ongoing pure tones consisting of 250 and 4,000 Hz, and the magnitudes of frequency change were 10%, 25% or 50% from the base frequencies. N1 and P2 amplitudes and latencies as well as dipole source activation in the left and right hemispheres were measured for each condition. Results: Compared to the non-musician group, behavioral thresholds in the musician group were lower for frequency discrimination in quiet conditions only. The scalp-recorded N1 amplitudes were modulated as a function of frequency change. P2 amplitudes in the musician group were larger than in the non-musician group. Dipole source analysis showed that P2 dipole activity to frequency changes was lateralized to the right hemisphere, with greater activity in the musician group regardless of the hemisphere side. Additionally, N1 amplitudes to frequency changes were positively related to behavioral thresholds for frequency discrimination while enhanced P2 amplitudes were associated with a longer duration of musical training. Conclusions: Our results demonstrate that auditory cortical potentials evoked by frequency change are related to behavioral thresholds for frequency discrimination in musicians. Larger P2 amplitudes in musicians compared to non-musicians reflects musical training-induced neural plasticity.

Making Sense of Mismatch Negativity

Evoked potentials provide valuable insight into brain processes that are integral to our ability to interact effectively and efficiently in the world. The mismatch negativity (MMN) component of the evoked potential has proven highly informative on the ways in which sensitivity to regularity contributes to perception and cognition. This review offers a compendium of research on MMN with a view to scaffolding an appreciation for its use as a tool to explore the way regularities contribute to predictions about the sensory environment over many timescales. In compiling this work, interest in MMN as an index of sensory encoding and memory are addressed, as well as attention. Perspectives on the possible underlying computational processes are reviewed as well as recent observations that invite consideration of how MMN relates to how we learn, what we learn, and why.

Same or different pitch? Effects of musical expertise, pitch difference, and auditory task on the pitch discrimination ability of musicians and non-musicians

Musical expertise promotes both the perception and the processing of music. The aim of the present study was to analyze if musicians compared to non-musicians already have auditory processing advantages at the neural level. 50 musicians and 50 non-musicians worked on a task to determine the individual auditory difference threshold (individual JND threshold). A passive oddball paradigm followed while the EEG activity was recorded. Frequent standard sounds (528 hertz [Hz]) and rare deviant sounds (individual JND threshold, 535 Hz, and 558 Hz) were presented in the oddball paradigm. The mismatch negativity (MMN) and the P3a were used as indicators of auditory discrimination skills for frequency differences. Musicians had significantly smaller individual JND thresholds than non-musicians, but musicians were not faster than non-musicians. Musicians and non-musicians showed both the MMN and the P3a at the 535 Hz and 558 Hz condition. In the individual JND threshold condition, non-musicians, whose individual JND threshold was at 539.8 Hz (and therefore even above the deviant sound of 535 Hz), predictably showed the MMN and the P3a. Musicians, whose individual JND threshold was at 531.1 Hz (and thus close to the standard sound of 528 Hz), showed no MMN and P3a-although they were behaviorally able to differentiate frequencies individually within their JND threshold range. This may indicate a key role of attention in triggering the MMN during the detection of frequency differences in the individual JND threshold range (see Tervaniemi et al. in Exp Brain 161:1-10, 2005).

A generic deviance detection principle for cortical On/Off responses, omission response, and mismatch negativity

Neural responses to sudden changes can be observed in many parts of the sensory pathways at different organizational levels. For example, deviants that violate regularity at various levels of abstraction can be observed as simple On/Off responses of individual neurons or as cumulative responses of neural populations. The cortical deviance-related responses supporting different functionalities (e.g., gap detection, chunking, etc.) seem unlikely to arise from different function-specific neural circuits, given the relatively uniform and self-similar wiring patterns across cortical areas and spatial scales. Additionally, reciprocal wiring patterns (with heterogeneous combinations of excitatory and inhibitory connections) in the cortex naturally speak in favor of a generic deviance detection principle. Based on this concept, we propose a network model consisting of reciprocally coupled neural masses as a blueprint of a universal change detector. Simulation examples reproduce properties of cortical deviance-related responses including the On/Off responses, the omitted-stimulus response (OSR), and the mismatch negativity (MMN). We propose that the emergence of change detectors relies on the involvement of disinhibition. An analysis of network connection settings further suggests a supportive effect of synaptic adaptation and a destructive effect of N-methyl-D-aspartate receptor (NMDA-r) antagonists on change detection. We conclude that the nature of cortical reciprocal wiring gives rise to a whole range of local change detectors supporting the notion of a generic deviance detection principle. Several testable predictions are provided based on the network model. Notably, we predict that the NMDA-r antagonists would generally dampen the cortical Off response, the cortical OSR, and the MMN.

Deviance detection in sound frequency in simple and complex sounds in urethane-anesthetized rats

Mismatch negativity (MMN), which is an electrophysiological response demonstrated in humans and animals, reflects memory-based deviance detection in a series of sounds. However, only a few studies on rodents have used control conditions that were sufficient in eliminating confounding factors that could also explain differential responses to deviant sounds. Furthermore, it is unclear if change detection occurs similarly for sinusoidal and complex sounds. In this study, we investigated frequency change detection in urethane-anesthetized rats by recording local-field potentials from the dura above the auditory cortex. We studied change detection in sinusoidal and complex sounds in a series of experiments, controlling for sound frequency, probability, and pattern in a series of sounds. For sinusoidal sounds, the MMN controlled for frequency, adaptation, and pattern, was elicited at approximately 200 ms onset latency. For complex sounds, the MMN controlled for frequency and adaptation, was elicited at 60 ms onset latency. Sound frequency affected the differential responses. MMN amplitude was larger for the sinusoidal sounds than for the complex sounds. These findings indicate the importance of controlling for sound frequency and stimulus probabilities, which have not been fully controlled for in most previous animal and human studies. Future studies should confirm the preference for sinusoidal sounds over complex sounds in rats.

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.

The Role of Temporal Acoustic Exaggeration in High Variability Phonetic Training: A Behavioral and ERP Study

High variability phonetic training (HVPT) has been found to be effective in helping adult learners acquire non-native phonetic contrasts. The present study investigated the role of temporal acoustic exaggeration by comparing the canonical HVPT paradigm without involving acoustic exaggeration with a modified adaptive HVPT paradigm that integrated key temporal exaggerations in infant-directed speech (IDS). Sixty native Chinese adults participated in the training of the English /i/ and /i/ vowel contrast and were randomly assigned to three subject groups. Twenty were trained with the typical HVPT paradigm (the HVPT group), twenty were trained under the modified adaptive approach with acoustic exaggeration (the HVPT-E group), and twenty were in the control group. Behavioral tasks for the pre- and post- tests used natural word identification, synthetic stimuli identification, and synthetic stimuli discrimination. Mismatch negativity (MMN) responses from the HVPT-E group were also obtained to assess the training effects in within- and across- category discrimination without requiring focused attention. Like previous studies, significant generalization effects to new talkers were found in both the HVPT group and the HVPT-E group. The HVPT-E group, by contrast, showed greater improvement as reflected in larger progress in natural word identification performance. Furthermore, the HVPT-E group exhibited more native-like categorical perception based on spectral cues after training, together with corresponding training-induced changes in the MMN responses to within- and across- category differences. These data provide the initial evidence supporting the important role of temporal acoustic exaggeration with adaptive training in facilitating phonetic learning and promoting brain plasticity at the perceptual and pre-attentive neural levels.

Electrophysiological Correlates of Absolute Pitch in a Passive Auditory Oddball Paradigm: a Direct Replication Attempt

Humans with absolute pitch (AP) are able to effortlessly name the pitch class of a sound without an external reference. The association of labels with pitches cannot be entirely suppressed even if it interferes with task demands. This suggests a high level of automaticity of pitch labeling in AP. The automatic nature of AP was further investigated in a study by Rogenmoser et al. (2015). Using a passive auditory oddball paradigm in combination with electroencephalography, they observed electrophysiological differences between musicians with and without AP in response to piano tones. Specifically, the AP musicians showed a smaller P3a, an event-related potential (ERP) component presumably reflecting early attentional processes. In contrast, they did not find group differences in the mismatch negativity (MMN), an ERP component associated with auditory memory processes. They concluded that early cognitive processes are facilitated in AP during passive listening and are more important for AP than the preceding sensory processes. In our direct replication study on a larger sample of musicians with (n = 54, 27 females, 27 males) and without (n = 50, 24 females, 26 males) AP, we successfully replicated the non-significant effects of AP on the MMN. However, we could not replicate the significant effects for the P3a. Additional Bayes factor analyses revealed moderate to strong evidence (Bayes factor > 3) for the null hypothesis for both MMN and P3a. Therefore, the results of this replication study do not support the postulated importance of cognitive facilitation in AP during passive tone listening.

Neural discrimination of speech sound changes in a variable context occurs irrespective of attention and explicit awareness

To process complex stimuli like language, our auditory system must tolerate large acoustic variance, like speaker variability, and still be sensitive enough to discriminate between phonemes and to detect complex sound relationships in, e.g., prosodic cues. Our study determined discrimination of speech sounds in input mimicking natural speech variability, and detection of deviations in regular pitch relationships (rule violations) between speech sounds. We investigated the automaticity and the influence of attention and explicit awareness on these changes by recording the neurophysiological mismatch negativity (MMN) and P3a as well as task performance from 21 adults. The results showed neural discrimination of phonemes and rule violations as indicated by MMN and P3a, regardless of whether the sounds were attended or not, even when participants could not explicitly describe the rule. While small sample size precluded statistical analysis of some outcomes, we still found preliminary associations between the MMN amplitudes, task performance, and emerging explicit awareness of the rule. Our results highlight the automaticity of processing complex aspects of speech as a basis for the emerging conscious perception and explicit awareness of speech properties. While MMN operates at the implicit processing level, P3a appears to work at the borderline of implicit and explicit.

Using rotated speech to approximate the acoustic mismatch negativity response to speech

The mismatch negativity (MMN) response is influenced by the magnitude of the acoustic difference between standard and deviant, and the response is typically larger to linguistically relevant changes than to linguistically irrelevant changes. Linguistically relevant changes between standard and deviant typically co-occur with differences between the two acoustic signals. It is therefore not straightforward to determine the contribution of each of those two factors to the MMN response. This study investigated whether spectrally rotated speech can be used to determine the impact of the acoustic difference on the MMN response to a combined linguistic and acoustic change between standard and deviant. Changes between rotated vowels elicited an MMN of comparable amplitude to the one elicited by a within-category vowel change, whereas the between-category vowel change resulted in an MMN amplitude of greater magnitude. A change between rotated vowels resulted in an MMN ampltude more similar to that of a within-vowel change than a complex tone change did. This suggests that the MMN amplitude reflecting the acoustic difference between two speech sounds can be well approximated by the MMN amplitude elicited in response to their rotated counterparts, in turn making it possible to estimate the part of the response specific to the linguistic difference.

Low-level neural auditory discrimination dysfunctions in specific language impairment-A review on mismatch negativity findings

In specific language impairment (SLI), there is a delay in the child’s oral language skills when compared with nonverbal cognitive abilities. The problems typically relate to phonological and morphological processing and word learning. This article reviews studies which have used mismatch negativity (MMN) in investigating low-level neural auditory dysfunctions in this disorder. With MMN, it is possible to tap the accuracy of neural sound discrimination and sensory memory functions. These studies have found smaller response amplitudes and longer latencies for speech and non-speech sound changes in children with SLI than in typically developing children, suggesting impaired and slow auditory discrimination in SLI. Furthermore, they suggest shortened sensory memory duration and vulnerability of the sensory memory to masking effects. Importantly, some studies reported associations between MMN parameters and language test measures. In addition, it was found that language intervention can influence the abnormal MMN in children with SLI, enhancing its amplitude. These results suggest that the MMN can shed light on the neural basis of various auditory and memory impairments in SLI, which are likely to influence speech perception.

Effect of EEG Referencing Methods on Auditory Mismatch Negativity

Auditory event-related potentials (ERPs) have consistently been used in the investigation of auditory and cognitive processing in the research and clinical laboratories. There is currently no consensus on the choice of appropriate reference for auditory ERPs. The most commonly used references in auditory ERP research are the mathematically linked-mastoids (LM) and average referencing (AVG). Since LM and AVG referencing procedures do not solve the issue of electrically-neutral reference, Reference Electrode Standardization Technique (REST) was developed to create a neutral reference for EEG recordings. The aim of the current research is to compare the influence of the reference on amplitude and latency of auditory mismatch negativity (MMN) as a function of magnitude of frequency deviance across three commonly used electrode montages (16, 32, and 64-channel) using REST, LM, and AVG reference procedures. The current study was designed to determine if the three reference methods capture the variation in amplitude and latency of MMN with the deviance magnitude. We recorded MMN from 12 normal hearing young adults in an auditory oddball paradigm with 1,000 Hz pure tone as standard and 1,030, 1,100, and 1,200 Hz as small, medium and large frequency deviants, respectively. The EEG data recorded to these sounds was re-referenced using REST, LM, and AVG methods across 16-, 32-, and 64-channel EEG electrode montages. Results revealed that while the latency of MMN decreased with increment in frequency of deviant sounds, no effect of frequency deviance was present for amplitude of MMN. There was no effect of referencing procedure on the experimental effect tested. The amplitude of MMN was largest when the ERP was computed using LM referencing and the REST referencing produced the largest amplitude of MMN for 64-channel montage. There was no effect of electrode-montage on AVG referencing induced ERPs. Contrary to our predictions, the results suggest that the auditory MMN elicited as a function of increments in frequency deviance does not depend on the choice of referencing procedure. The results also suggest that auditory ERPs generated using REST referencing is contingent on the electrode arrays more than the AVG referencing.

Phoneme processing skills are reflected in children's MMN responses

Phonological awareness (PA), the core contributor in phoneme processing abilities, has a link to later reading skills in children. However, the associations between PA and neural auditory discrimination are not clear. We used event-related potential (ERP) methodology and neuropsychological testing to monitor the neurocognitive basis of phonological awareness in typically developing children. We measured 5-6-year-old children's (N=70) phoneme processing, word completion and perceptual reasoning skills and compared their test results to their brain responses to phonemic changes, separately for each test. We found that children performing better in Phoneme processing test showed larger mismatch negativity (MMN) responses than children scoring lower in the same test. In contrast, no correspondence between test scores and brain responses was found for Auditory closure. Thus, the results suggest that automatic auditory change detection is linked to phoneme awareness in preschool children.

How regularity representations of short sound patterns that are based on relative or absolute pitch information establish over time: An EEG study

The recognition of sound patterns in speech or music (e.g., a melody that is played in different keys) requires knowledge about pitch relations between successive sounds. We investigated the formation of regularity representations for sound patterns in an event-related potential (ERP) study. A pattern, which consisted of six concatenated 50 ms tone segments differing in fundamental frequency, was presented 1, 2, 3, 6, or 12 times and then replaced by another pattern by randomly changing the pitch of the tonal segments (roving standard paradigm). In an absolute repetition condition, patterns were repeated identically, whereas in a transposed condition, only the pitch relations of the tonal segments of the patterns were repeated, while the entire patterns were shifted up or down in pitch. During ERP measurement participants were not informed about the pattern repetition rule, but were instructed to discriminate rarely occurring targets of lower or higher sound intensity. EPRs for pattern changes (mismatch negativity, MMN; and P3a) and for pattern repetitions (repetition positivity, RP) revealed that the auditory system is able to rapidly extract regularities from unfamiliar complex sound patterns even when absolute pitch varies. Yet, enhanced RP and P3a amplitudes, and improved behavioral performance measured in a post-hoc test, in the absolute as compared with the transposed condition suggest that it is more difficult to encode patterns without absolute pitch information. This is explained by dissociable processing of standards and deviants as well as a back propagation mechanism to early sensory processing stages, which is effective after less repetitions of a standard stimulus for absolute pitch.

Longitudinal auditory learning facilitates auditory cognition as revealed by microstate analysis

The current study investigates cognitive processes as reflected in late auditory-evoked potentials as a function of longitudinal auditory learning. A normal hearing adult sample (n=15) performed an active oddball task at three consecutive time points (TPs) arranged at two week intervals, and during which EEG was recorded. The stimuli comprised of syllables consisting of a natural fricative (/sh/,/s/,/f/) embedded between two /a/ sounds, as well as morphed transitions of the two syllables that served as deviants. Perceptual and cognitive modulations as reflected in the onset and the mean global field power (GFP) of N2b- and P3b-related microstates across four weeks were investigated. We found that the onset of P3b-like microstates, but not N2b-like microstates decreased across TPs, more strongly for difficult deviants leading to similar onsets for difficult and easy stimuli after repeated exposure. The mean GFP of all N2b-like and P3b-like microstates increased more in spectrally strong deviants compared to weak deviants, leading to a distinctive activation for each stimulus after learning. Our results indicate that longitudinal training of auditory-related cognitive mechanisms such as stimulus categorization, attention and memory updating processes are an indispensable part of successful auditory learning. This suggests that future studies should focus on the potential benefits of cognitive processes in auditory training.

Rubberband Effect in Temporal Control of Mismatch Negativity

Mismatch negativity (MMN) is a difference event-related potential (ERP) wave reflecting the brain’s automatic reaction to deviant sensory stimuli, and it has been proven to be a useful tool in research on cognitive functions or clinical disorders. In most MMN studies, amplitude, peak latency, or the integral of the responses, in rare cases also the slopes of the responses, have been employed as parameters of the ERP responses for quantitative analyses. However, little is known about correlations between these parameters. To better understand the relations between different ERP parameters, we extracted and correlated several different parameters characterizing the MMN waves. We found an unexpected correlation which gives new insight into the temporal control of MMN: response amplitudes are positively correlated with downside slopes, whereas barely correlated with upside slopes. This result suggests an efficient feedback mechanism for the MMN to return to the baseline within a predefined time window, contradicting an exponential decay function as one might expect. As a metaphor we suggest a rubberband effect for the MMN responses, i.e., the larger the distance of the response from neural equilibrium, the stronger the return force to equilibrium.

Cortical encoding and neurophysiological tracking of intensity and pitch cues signaling English stress patterns in native and nonnative speakers

We examined cross-language differences in neural encoding and tracking of intensity and pitch cues signaling English stress patterns. Auditory mismatch negativities (MMNs) were recorded in English and Mandarin listeners in response to contrastive English pseudowords whose primary stress occurred either on the first or second syllable (i.e., "nocTICity" vs. "NOCticity"). The contrastive syllable stress elicited two consecutive MMNs in both language groups, but English speakers demonstrated larger responses to stress patterns than Mandarin speakers. Correlations between the amplitude of ERPs and continuous changes in the running intensity and pitch of speech assessed how well each language group's brain activity tracked these salient acoustic features of lexical stress. We found that English speakers' neural responses tracked intensity changes in speech more closely than Mandarin speakers (higher brain-acoustic correlation). Findings demonstrate more robust and precise processing of English stress (intensity) patterns in early auditory cortical responses of native relative to nonnative speakers.

Psychophysiological Correlates of Developmental Changes in Healthy and Autistic Boys

This study investigated neurodevelopmental changes in sound processing by recording mismatch negativity (MMN) in response to various degrees of sound complexity in 18 mildly to moderately autistic versus 15 healthy boys aged between 6 and 15 years. Autistic boys presented with lower IQ and poor performance on a range of executive and social function measures when compared to their healthy counterparts. We found that MMN in response to duration deviants was less lateralized in the clinical group whereas larger amplitudes correlated with advanced age, thus capturing neurodevelopmental changes. Larger MMN in response to speech-like sound deviants was associated with better verbal fluency and executive function performance, respectively, but did not reliably discriminate the two groups.

Interaction of Musicianship and Aging: A Comparison of Cortical Auditory Evoked Potentials

Objective. The goal of this study was to begin to explore whether the beneficial auditory neural effects of early music training persist throughout life and influence age-related changes in neurophysiological processing of sound. Design. Cortical auditory evoked potentials (CAEPs) elicited by harmonic tone complexes were examined, including P1-N1-P2, mismatch negativity (MMN), and P3a. Study Sample. Data from older adult musicians (n = 8) and nonmusicians (n = 8) (ages 55–70 years) were compared to previous data from young adult musicians (n = 40) and nonmusicians (n = 20) (ages 18–33 years). Results. P1-N1-P2 amplitudes and latencies did not differ between older adult musicians and nonmusicians; however, MMN and P3a latencies for harmonic tone deviances were earlier for older musicians than older nonmusicians. Comparisons of P1-N1-P2, MMN, and P3a components between older and young adult musicians and nonmusicians suggest that P1 and P2 latencies are significantly affected by age, but not musicianship, while MMN and P3a appear to be more sensitive to effects of musicianship than aging. Conclusions. Findings support beneficial influences of musicianship on central auditory function and suggest a positive interaction between aging and musicianship on the auditory neural system.

Is it time to move mismatch negativity into the clinic?

Since its inception in the 1970s, the mismatch negativity (MMN) event-related potential has improved our understanding of pre-attentive detection of rule violations, which is a fundamental cognitive process considered by some a form of "primitive intelligence". The body of research to date ranges from animal studies (i.e. when investigating the neural mechanisms and pharmacological properties of MMN generation) to researching the psychophysiological nature of human consciousness. MMN therefore offers the possibility to detect abnormal functioning in the neural system involved in MMN generation, such as it occurs in some neurodevelopmental disorders or patients in vegetative state. While the clinical research data holds considerable promise for translation into clinical practice, standardization and normative data of an optimized (i.e. disorder-specific) MMN recording algorithm is needed in order for MMN to become a valuable clinical investigation tool.

Absolute Pitch: Evidence for Early Cognitive Facilitation during Passive Listening as Revealed by Reduced P3a Amplitudes

Absolute pitch (AP) is the rare ability to identify or produce different pitches without using reference tones. At least two sequential processing stages are assumed to contribute to this phenomenon. The first recruits a pitch memory mechanism at an early stage of auditory processing, whereas the second is driven by a later cognitive mechanism (pitch labeling). Several investigations have used active tasks, but it is unclear how these two mechanisms contribute to AP during passive listening. The present work investigated the temporal dynamics of tone processing in AP and non-AP (NAP) participants by using EEG. We applied a passive oddball paradigm with between- and within-tone category manipulations and analyzed the MMN reflecting the early stage of auditory processing and the P3a response reflecting the later cognitive mechanism during the second processing stage. Results did not reveal between-group differences in MMN waveforms. By contrast, the P3a response was specifically associated with AP and sensitive to the processing of different pitch types. Specifically, AP participants exhibited smaller P3a amplitudes, especially in between-tone category conditions, and P3a responses correlated significantly with the age of commencement of musical training, suggesting an influence of early musical exposure on AP. Our results reinforce the current opinion that the representation of pitches at the processing level of the auditory-related cortex is comparable among AP and NAP participants, whereas the later processing stage is critical for AP. Results are interpreted as reflecting cognitive facilitation in AP participants, possibly driven by the availability of multiple codes for tones.

Are scalar implicatures automatically processed and different for each individual? A mismatch negativity (MMN) study

Scalar implicatures are ordinarily activated in human communication when the speaker uses a weak expression (e.g., some) from a set of stronger alternatives (e.g., many, all). It has been debated whether scalar inferences are generated by default. To clarify this issue and examine whether individual pragmatic ability will affect the mechanism of scalar inference processing, we performed experiment with an MMN paradigm to capture the neurophysiological indicators of automatic processing of spoken sentences and divided participants into high and low pragmatic ability groups. Experimental results showed that compared with the condition that an informative sentence ("Some animals have tails") is the deviant stimuli, when an underinformative sentence ("Some tigers have tails") is the deviant stimuli, the high pragmatic ability group induced mismatch negativity (MMN) and sustained negativity, while the low pragmatic ability group had no ERP effects. These results indicated that at least some people can automatically activate the scalar implicatures when encountering scalar trigger words, even in the inattentive status.

Visual mismatch negativity: a predictive coding view

An increasing number of studies investigate the visual mismatch negativity (vMMN) or use the vMMN as a tool to probe various aspects of human cognition. This paper reviews the theoretical underpinnings of vMMN in the light of methodological considerations and provides recommendations for measuring and interpreting the vMMN. The following key issues are discussed from the experimentalist's point of view in a predictive coding framework: (1) experimental protocols and procedures to control "refractoriness" effects; (2) methods to control attention; (3) vMMN and veridical perception.

Frequency difference beyond behavioral limen reflected by frequency following response of human auditory Brainstem

Background

The present study investigated whether the frequency-following response (FFR) of the auditory brainstem can represent individual frequency-discrimination ability.

Method

We measured behavioral frequency-difference limens (FDLs) in normal hearing young adults. Then FFRs were evoked by two pure tones, whose frequency difference was no larger than behavioral FDL. Discrimination of FFRs to individual frequencies was conducted as the neural representation of stimulus frequency difference. Participants were 15 Chinese college students (ages 19–25; 3 males, 12 females) with normal hearing characteristics.

Results

According to discriminative neural representations of individual frequencies, FFRs accurately reflected individual FDLs and detected stimulus-frequency differences smaller than behavioral threshold (e.g., 75% of FDL).

Conclusions

These results suggest that when a frequency difference cannot be behaviorally distinguished, there is still a possibility of it being detected physiologically.

Atypical mismatch negativity in response to emotional voices in people with autism spectrum conditions

Autism Spectrum Conditions (ASC) are characterized by heterogeneous impairments of social reciprocity and sensory processing. Voices, similar to faces, convey socially relevant information. Whether voice processing is selectively impaired remains undetermined. This study involved recording mismatch negativity (MMN) while presenting emotionally spoken syllables dada and acoustically matched nonvocal sounds to 20 subjects with ASC and 20 healthy matched controls. The people with ASC exhibited no MMN response to emotional syllables and reduced MMN to nonvocal sounds, indicating general impairments of affective voice and acoustic discrimination. Weaker angry MMN amplitudes were associated with more autistic traits. Receiver operator characteristic analysis revealed that angry MMN amplitudes yielded a value of 0.88 (p<.001). The results suggest that people with ASC may process emotional voices in an atypical fashion already at the automatic stage. This processing abnormality can facilitate diagnosing ASC and enable social deficits in people with ASC to be predicted.

Musicianship facilitates the processing of Western music chords--an ERP and behavioral study

The present study addressed the effects of musicianship on neural and behavioral discrimination of Western music chords. In abstract oddball paradigms, minor chords and inverted major chords were presented in the context of major chords to musician and non-musician participants in a passive listening task (with EEG recordings) and in an active discrimination task. Both sinusoidal sounds and harmonically rich piano sounds were used. Musicians outperformed non-musicians in the discrimination task. Change-related mismatch negativity (MMN) was evoked to minor and inverted major chords in musicians only, and N1 amplitude was larger in musicians than non-musicians. While MMN was absent in non-musicians, both groups showed decreased N1 in response to minor compared to major chords. The results indicate that processing of complex musical stimuli is enhanced in musicians both behaviorally and neurally, but that major-minor chord categorization is present to some extent also in the absence of music training.

Beat processing is pre-attentive for metrically simple rhythms with clear accents: an ERP study

The perception of a regular beat is fundamental to music processing. Here we examine whether the detection of a regular beat is pre-attentive for metrically simple, acoustically varying stimuli using the mismatch negativity (MMN), an ERP response elicited by violations of acoustic regularity irrespective of whether subjects are attending to the stimuli. Both musicians and non-musicians were presented with a varying rhythm with a clear accent structure in which occasionally a sound was omitted. We compared the MMN response to the omission of identical sounds in different metrical positions. Most importantly, we found that omissions in strong metrical positions, on the beat, elicited higher amplitude MMN responses than omissions in weak metrical positions, not on the beat. This suggests that the detection of a beat is pre-attentive when highly beat inducing stimuli are used. No effects of musical expertise were found. Our results suggest that for metrically simple rhythms with clear accents beat processing does not require attention or musical expertise. In addition, we discuss how the use of acoustically varying stimuli may influence ERP results when studying beat processing.