Blog Archives

Effects of auditory hallucinations on the mismatch negativity (MMN) in schizophrenia as measured by a modified ‘optimal’ multi-feature paradigm

Conclusions
This is the first study to examine MMN in SZ and to report a significant difference in duration MMN amplitude between patients and healthy within the modified (Optimal-3) multi-feature MMN paradigm. This study corroborates previous research reporting a robust duration MMN deficit in schizophrenia and supports previous findings suggesting that AHs may contribute to MMN deficits in schizophrenia.

from the International Journal of Psychophysiology

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The representation of unattended, segmented sounds: A mismatch negativity (MMN) study

The detection of an irregular, potentially relevant change (deviance) in the regular, unattended acoustic environment is ensured by the automatic deviance detection mechanism. It underlies the formation of a regularity representation and a comparison of an incoming sound with this representation. A mismatch outcome of this comparison evokes the mismatch negativity (MMN) of the event-related potential. For unattended pure tones the automatic deviance detection mechanism operates most efficiently for initial sound parts, which is why these are suggested to contribute more to sound representation than later parts. A transient that physically segments the sounds can overcome this temporal constraint in sound representation. Whether the resulting individual (initial and terminal) sound segments or the joined two-segments give rise to the regularity representation is addressed here. We took advantage that the MMN attenuation to the second of two successive deviances (deviance-repetition effect) is more pronounced when the deviances belong to the same unit of representation. We measured MMN for two deviances (frequency modulations) within segmented sounds that either occurred within the initial or the terminal segment, or that were split across both segments. Unexpectedly, we did not obtain a deviance-repetition effect. Instead, we obtained a temporal distance effect: With increasing temporal distance from deviance-onset relative to segment-onset the MMN amplitude decreased. Furthermore, this effect did not depend on whether the deviance occurred in the initial or in the terminal segment. Thus, (for the current approach) we suggest that the regularity representation is based on the individual rather than joined segments.

from the International Journal of Psychophysiology

Could audiovisual training be used to improve cognition in extremely low birth weight children?

Conclusions:  Although all children did not complete the protocol, the results suggest that training with Audilex dyslexia programme might be beneficial for enhancing neural-level sound discrimation and possibly reading skills in ELBW children. A larger trial is warranted.

from Acta Paediatrica

“What you encode is not necessarily what you store”: Evidence for sparse feature representations from mismatch negativity

The present study examines whether vowels embedded in complex stimuli may possess underspecified representations in the mental lexicon. A second goal was to assess the possible interference of the lexical status of stimuli under study. Minimal pairs of German nouns differing only in the stressed vowels [e], [ø], [o], and derived pseudowords, were used to measure the Mismatch Negativity (MMN) in a passive oddball-paradigm. The differing vowels were chosen such that the place of articulation information was conflicting vs. non-conflicting in the framework of models assuming underspecified representations in the mental lexicon (i.e. minimizing featural information by omitting redundant information in order to ensure efficient speech processing), whereas models assuming fully specified phonological representations would predict equal levels of conflict in all possible contrasts. The observed pattern of MMN amplitude differences was in accordance to predictions of models assuming underspecified phonological representations. As the possible interferences by other levels of linguistic processing was demonstrated, it seems favourable to use pseudowords for investigating phonological effects by means of MMN.

from Brain Research

Mismatch Negativity and Adaptation Measures of the Late Auditory Evoked Potential in Cochlear Implant Users

A better understanding of the neural correlates of large variability in cochlear implant (CI) patients’ speech performance may allow us to find solutions to further improve CI benefits. The present study examined the mismatch negativity (MMN) and the adaptation of the late auditory evoked potential (LAEP) in 10 CI users. The speech syllable /da/ and 1-kHz tone burst were used to examine the LAEP adaptation. The amount of LAEP adaptation was calculated according to the averaged N1-P2 amplitude for the LAEPs evoked by the last 3 stimuli and the amplitude evoked by the first stimulus. For the MMN recordings, the standard stimulus (1-kHz tone) and the deviant stimulus (2-kHz tone) were presented in an oddball condition. Additionally, the deviants alone were presented in a control condition. The MMN was derived by subtracting the response to the deviants in the control condition from the oddball condition. Results showed that good CI performers displayed a more prominent LAEP adaptation than moderate-to-poor performers. Speech performance was significantly correlated to the amount of LAEP adaptation for the 1-kHz tone bursts. Good performers displayed large MMNs and moderate-to-poor performers had small or absent MMNs. The abnormal electrophysiological findings in moderate-to-poor performers suggest that long-term deafness may cause damage not only at the auditory cortical level, but also at the cognitive level.

from Hearing Research

Occurrence of Mismatch Negativity in Response to Changes in the Durations of Short Pauses during Continuous Auditory Stimulation

Mismatch negativity (MMN) is a component of the auditory evoked potential which is widely used in research and clinical investigations. Using the oddball paradigm, which is traditional for obtaining mismatch negativity, we recorded MMN-like responses to changes in the duration of short pauses (standard = 25 msec; deviant = 50 msec, and vice versa) on the background of continuous auditory stimulation (1 kHz, 50 dB). Our data show that this is the first description of this type of mismatch negativity. We compared the responses to changes in pause duration with “classical” mismatch negativity to changes in pause duration with the same time characteristics. Mismatch negativity to changes in pauses was characterized by longer latent periods and the absence of significant inversion in the mastoid leads. Both responses, to changes in sound duration and to changes in pause duration, demonstrated shorter latent periods when the deviants were longer than the standards as compared with the reverse situation. This new type of mismatch negativity may widen the potential for its use in clinical and research studies.

from Neuroscience and Behavioral Physiology

Congruency of auditory sounds and visual letters modulates mismatch negativity and P300 event-related potentials

A key determinant of skilled reading is the ability to integrate the orthographic and auditory forms of language. A number of prior studies have identified neural markers in adult readers corresponding to audio-visual integration of letters and their corresponding sounds. However, there remains some controversy as to the stage of processing at which this occurs. In the present study, we examined this issue using event-related potentials (ERPs), due to their sensitivity to the timing of perceptual and cognitive processes. Letter sounds were presented auditorily in an unattended mismatch negativity (MMN) paradigm, which is argued to be indicative of auditory-sensory memory. Concurrently, participants performed a visual letter identification task. On critical trials, the auditory stimulus was played concurrently with the visual letters. We observed significant MMNs both when the visual letter was congruent with the auditory stimulus, and when it was incongruent. However, the magnitude and scalp distribution of this effect was attenuated in incongruent trials. We also observed a later-going effect of congruency on P300 trials, marked by increased amplitudes and latencies for incongruent compared to congruent trials. The results suggest audiovisual integration of letters and sounds can and does occur during relatively early pre-attentive stages of sensory processing, and that these effects extend to later-going attentional phases of processing as well.

from the International Journal of Psychophysiology

Speech-feature discrimination in children with Asperger syndrome as determined with the multi-feature mismatch negativity paradigm

Conclusions
Cortical speech-sound discrimination is aberrant in children with Asperger syndrome. This is evident both as hypersensitive and depressed neural reactions to speech-sound changes, and is associated with features (frequency, intensity) which are relevant for prosodic processing.

from Clinical Neurophysiology

Interhemisphere Asymmetry of Auditory Evoked Potentials in Humans and Mismatch Negativity during Sound Source Localization

Results of studies in humans of long-latency auditory evoked potentials and mismatch negativity in conditions of dichotic stimulation during presentation of deviant stimuli producing instantaneous changes in stimulus azimuth from the null to +22.5° or movement at rates of 11.25–112.5°/sec from the midline of the head across the left and right hemispheres towards each ear are presented. These studies showed that the total amplitude of the components of the N1–P2 complex of auditory evoked potentials in the frontal lead of the right hemisphere was greater than that in the left hemisphere. Mismatch negativity parameters showed significant relationships with the spatial position of the sound source, namely, its displacement into the right hemisphere from the position of the sound image of the standard signal. Questions of the involvement of the right hemisphere in discriminating the spatial characteristics of sound sources are discussed.

from Neuroscience and Behavioral Psychology

Electrophysiological Indices of Discrimination of Long-Duration, Phonetically Similar Vowels in Children With Typical and Atypical Language Development

Conclusions: Increased vowel duration can improve discrimination in children with SLI. However, poor identification of these longer vowels by some children with SLI suggests a deficit in long-term phonological representations or accessing these representations.

from the Journal of Speech, Language, and Hearing Research

Differences in the neural basis of automatic auditory and visual time perception: ERP evidence from an across-modal delayed response oddball task

In our everyday lives, we need to process auditory and visual temporal information as efficiently as possible. Although automatic auditory time perception has been widely investigated using an index of the mismatch negativity (MMN), the neural basis of automatic visual time perception has been largely ignored. The present study investigated the automatic processing of auditory and visual time perception employing the cross-modal delayed response oddball paradigm. In the experimental condition, the standard stimulus was 200 ms and the deviant stimulus was 120 ms, which were exchanged in the control condition. Reaction time, accuracy, and event-related potential (ERP) data were measured when participants performed the duration discrimination task. The ERP results showed that the MMN, N2b, and P3 were elicited by an auditory deviant stimulus under the attention condition, while only the MMN was elicited under the inattention condition. The MMN was largest over the frontal and central sites, while the difference in MMN amplitude was not significant between under the attention and inattention condition. In contrast, the change related positivity (CRP) and the visual mismatch negativity (vMMN) were elicited by the visual deviant stimulus under both the attention and inattention conditions. The CRP was largest over the occipito-temporal sites under the attention condition, and over the fronto-central sites under the inattention condition. The difference in CRP amplitude was significant between the attention and inattention condition. The vMMN was largest over the parieto-occipital sites under the attention condition, and largest over the fronto-central sites under the inattention condition. The difference in vMMN amplitude was significant between the attention and inattention condition. Auditory MMN does not appear to be modulated by attention, whereas the visual CRP and the vMMN are modulated by attention. Therefore, the present study provides electrophysiological evidence for the existence of automatic visual time perception, and supports an “attentional switch” hypothesis for a modality effect on duration judgments, such that auditory temporal information is processed relatively automatically, whereas visual temporal information processing requires controlled attention.

from Brain Research

Auditory mismatch negativity deficits in long-term heavy cannabis users

Abstract Mismatch negativity (MMN) is an auditory event-related potential indicating auditory sensory memory and information processing. The present study tested the hypothesis that chronic cannabis use is associated with deficient MMN generation. MMN was investigated in age- and gender-matched chronic cannabis users (n = 30) and nonuser controls (n = 30). The cannabis users were divided into two groups according to duration and quantity of cannabis consumption. The MMNs resulting from a pseudorandomized sequence of 2 × 900 auditory stimuli were recorded by 32-channel EEG. The standard stimuli were 1,000 Hz, 80 dB SPL and 90 ms duration. The deviant stimuli differed in duration (50 ms) or frequency (1,200 Hz). There were no significant differences in MMN values between cannabis users and nonuser controls in both deviance conditions. With regard to subgroups, reduced amplitudes of frequency MMN at frontal electrodes were found in long-term (≥8 years of use) and heavy (≥15 joints/week) users compared to short-term and light users. The results indicate that chronic cannabis use may cause a specific impairment of auditory information processing. In particular, duration and quantity of cannabis use could be identified as important factors of deficient MMN generation.

from the European Archives of Psychiatry and Clinical Neuroscience

Neuropsychological correlates of auditory perceptual inference: A mismatch negativity (MMN) study

The mismatch negativity (MMN) component of the auditory event-related potential can be used to study automatic perceptual inference. This study was designed to explore “Conditional Inference” in the MMN system – the capacity of the auditory system to use current input to switch between inference models in memory. We presented a “Random” sequence comprising a standard repeating sound occasionally interrupted by a change in frequency, duration or intensity (louder or softer). We also presented the same sequence with a conditional linkage between deviants – that is, frequency and duration deviants always followed an intensity change. We explored whether the auditory system could use intensity deviance to change the inference from “expect the standard to repeat” to “expect a frequency or duration violation” and quantified this as the proportion decline in the MMN elicited to duration and frequency deviant sounds in the linked versus random sequence. We report three main outcomes on a sample of 25 healthy young adults: (1) there was a significant conditional inference effect (a reduction in MMN amplitude in linked versus random sequences) to duration but not frequency deviants; (2) larger simple MMN and larger conditional inference effect on duration MMN were correlated with higher Digit Span; and (3) the conditional inference effect but not simple MMN to duration deviants, was strongly correlated with working memory ability (rs=.78, p<.001). The results are discussed with respect to the differential cognitive demands of simple MMN and conditional inference, and the possible involvement of prefrontal cortex in implementing conditional inference in the MMN system.

from Brain Research

Hemispheric Specialization during Discrimination of Sound Sources reflected by MMN

The present study reports the hemispheric specificity of spatial auditory processing in 15 healthy subjects by measuring location mismatch negativity (MMN) under free field stimulation. The aim was to decide between the partly inconsistent hypotheses of contralateral and/or right-hemispheric dominance in spatial processing in the auditory cortex. The laterality of deviant-standard positions were systematically varied covering the whole of the frontal hemifield from 90° left to 90° right, while the spatial separation of deviant and standard were fixed at 17°. This enabled the evaluation of the specific location-MMNs relating to distinct cortical processing of acoustic space. The inter-hemispheric comparison of the amplitudes of MMNs showed that spatial deviation towards the periphery at -/+17° (relative to 0°-standard) and at -/+90° (relative to -/+73°-standard) elicited a salient contralateral activation. In contrast, positional changes towards front at -/+56° positions (relative to -/+73°-standard) resulted equal bilateral MMNs. Further, MMN latencies became longer with increasing laterality of respective deviant-standard pairs. Thus, the present study suggests a contralateral pre-attentive cortical processing of acoustic space information in the free field. The direction of positional changes (‘towards periphery’ vs. ‘towards front’) seems to augment or reduce this contralateral effect. The sound source discrimination performance across space is also mirrored by the location-MMN latency.

from Neuropsychologia

ERP Evaluation of Auditory Sensory Memory Systems in Adults with Intellectual Disability

Abstract
Auditory sensory memory stage can be functionally divided into two subsystems; transient-detector system and permanent feature-detector system (Ntnen, 1992). We assessed these systems in persons with intellectual disability by measuring event-related potentials (ERPs) N1 and mismatch negativity (MMN), which reflect the two auditory subsystems, respectively. Added to these, P3a (an ERP reflecting stage after sensory memory) was evaluated. Either synthesized vowels or simple tones were delivered during a passive oddball paradigm to adults with and without intellectual disability. ERPs were recorded from midline scalp sites (Fz, Cz, and Pz). Relative to control group, participants with the disability exhibited greater N1 latency and less MMN amplitude. The results for N1 amplitude and MMN latency were basically comparable between both groups. IQ scores in participants with the disability revealed no significant relation with N1 and MMN measures, whereas the IQ scores tended to increase significantly as P3a latency reduced. These outcomes suggest that persons with intellectual disability might own discrete malfunctions for the two detector systems in auditory sensory-memory stage. Moreover, the processes following sensory memory might be partly related to a determinant of mental development.

from the International Journal of Neuroscience