1,726,273 research outputs found
Event-related brain potential correlates of human auditory sensory memory-trace formation
No full textThe event-related potential (ERP) component mismatch negativity (MMN) is a neural marker of human echoic memory. MMN is elicited by deviant sounds embedded in a stream of frequent standards, reflecting the deviation from an inferred memory trace of the standard stimulus. The strength of this memory trace is thought to be proportional to the number of repetitions of the standard tone, visible as the progressive enhancement of MMN with number of repetitions (MMN memory-trace effect). However, no direct ERP correlates of the formation of echoic memory traces are currently known. This study set out to investigate changes in ERPs to different numbers of repetitions of standards, delivered in a roving-stimulus paradigm in which the frequency of the standard stimulus changed randomly between stimulus trains. Normal healthy volunteers (n = 40) were engaged in two experimental conditions: during passive listening and while actively discriminating changes in tone frequency. As predicted, MMN increased with increasing number of standards. However, this MMN memory-trace effect was caused mainly by enhancement with stimulus repetition of a slow positive wave from 50 to 250 ms poststimulus in the standard ERP, which is termed here "repetition positivity" (RP). This RP was recorded from frontocentral electrodes when participants were passively listening to or actively discriminating changes in tone frequency. RP may represent a human ERP correlate of rapid and stimulus-specific adaptation, a candidate neuronal mechanism underlying sensory memory formation in the auditory cortex
Saliency or template? ERP evidence for long-term representation of word stress
Full text linkThe present study investigated the event-related brain potential (ERP) correlates of word stress processing. Previous results showed that the violation of a legal stress pattern elicited two consecutive Mismatch Negativity (MMN) components synchronized to the changes on the first and second syllable. The aim of the present study was to test whether ERPs reflect only the detection of salient features present on the syllables, or they reflect the activation of long-term stress related representations.
We examined ERPs elicited by pseudowords with no lexical representation in two conditions: the standard having a legal stress patterns, and the deviant an illegal one, and the standard having an illegal stress pattern, and the deviant a legal one. We found that the deviant having an illegal stress pattern elicited two consecutive MMN components, whereas the deviant having a legal stress pattern did not elicit MMN. Moreover, pseudowords with a legal stress pattern elicited the same ERP responses irrespective of their role in the oddball sequence, i.e., if they were standards or deviants.
The results suggest that stress pattern changes are processed relying on long-term representation of word stress. To account for these results, we propose that the processing of stress cues is based on language-specific, pre-lexical stress templates
Attentional Enhancement of Auditory Mismatch Responses: a DCM/MEG Study.
No full textDespite similar behavioral effects, attention and expectation influence evoked responses differently: Attention typically enhances event-related responses, whereas expectation reduces them. This dissociation has been reconciled under predictive coding, where prediction errors are weighted by precision associated with attentional modulation. Here, we tested the predictive coding account of attention and expectation using magnetoencephalography and modeling. Temporal attention and sensory expectation were orthogonally manipulated in an auditory mismatch paradigm, revealing opposing effects on evoked response amplitude. Mismatch negativity (MMN) was enhanced by attention, speaking against its supposedly pre-attentive nature. This interaction effect was modeled in a canonical microcircuit using dynamic causal modeling, comparing models with modulation of extrinsic and intrinsic connectivity at different levels of the auditory hierarchy. While MMN was explained by recursive interplay of sensory predictions and prediction errors, attention was linked to the gain of inhibitory interneurons, consistent with its modulation of sensory precision
The nature of speech representation in varying-standard MMN paradigm
No full textHestvik, ArildMismatch Negativity (MMN) studies have utilized the varying-standard oddball paradigm to investigate the effect of linguistic category on speech perception. But the evidence is missing for an MMN driven by a within-category acoustic contrast between standards and deviants. With three experiments, the current dissertation asks whether the memory trace in the varying-standard paradigms retains gradient information that could lead to an MMN response. ☐ Experiment 1 looked for an MMN response using the varying-standard paradigm without a categorical contrast between standards and deviants. The standards were realized by [tæ] with voice onset times (VOTs) of 42, 48, and 55ms VOT [tæ]s, and the deviants were realized by [tæ] with a 119ms VOT. The MMN was computed as the difference in brain response to deviants minus the same stimulus in a roving-standard control condition. A within-category MMN was observed, suggesting that the memory trace in the varying-standard paradigm must contain gradient information. ☐ Experiment 2 asked what drove the within-category MMN in Experiment 1. The observed within-category MMN could be due to the deviant VOT contrasting to the phonetic knowledge retrieved from long-term memory. Alternatively, it could be driven by a contrast between the deviant VOT and a statistical summary based on the presented standard VOTs. In that case, the MMN magnitude should be modulated by the statistical structure of the presented stimuli (Garrido, Sahani, & Dolan, 2013). Experiment 2 presented one group with a 128ms VOT [tæ] deviant embedded in a normal distribution of varying standards with a mean VOT of 64ms and a “wide” standard deviation of 15ms. It presented a second group with the same deviant and mean standard VOTs but with a “narrow” standard deviation of 5ms. The result replicated Experiment 1 with a within-category MMN, but no difference between the two standard deviation groups was observed. The lack of difference in the MMN magnitude suggests that a statistical summary of the presented stimuli could not explain the within-category MMN obtained in Experiment 1. ☐ As the conclusion of Experiment 2 was based on a null result, Experiment 3 was conducted to provide positive evidence for a statistical summary of the presented stimuli. Experiment 3 swapped the standards and deviants used in Experiment 2, such that the standard VOTs formed a distribution with a mean VOT of 128ms while the deviant VOT was 64ms. If the varying standards activate phonetic knowledge as a memory trace, the deviant VOT should not lead to an MMN, as the deviant VOT corresponds to the most typical phonetic realization of /tæ/. On the other hand, if the brain computes a statistical summary of standard VOTs, the acoustic difference between the standard and deviant VOT values should lead to an MMN response. The result was that the deviant VOT elicited a robust MMN, indexing the brain’s sensitivity to the statistical structure of the presented stimuli. ☐ The results of the three experiments confirmed that a speech MMN could be driven by a within-category difference other than a categorical contrast. This finding suggests that the memory representation in the varying-standard paradigm retains gradient information along with a category representation. Furthermore, the gradient information comes from the statistical summary based on the acoustic properties of the presented stimuli. The present work thus extends the prior research emphasizing the role episodic memory played in speech perception.University of Delaware, Department of Linguistics and Cognitive SciencePh.D
Sensory auditory processing and intuitive sound detection : an investigation of musical experts and nonexperts
No full textThe auditory system can detect occasional changes (deviants) in acoustic regularities without the need for subjects to focus their attention on the sound material. Deviant detection is reflected in the elicitation of the mismatch negativity component (MMN) of the event-related potentials. In the studies presented in this thesis, the MMN is used to investigate the auditory abilities for detecting similarities and regularities in sound streams. To investigate the limits of these processes, professional musicians have been tested in some of the studies. The results show that auditory grouping is already more advanced in musicians than in nonmusicians and that the auditory system of musicians can, unlike that of nonmusicians, detect a numerical regularity of always four tones in a series. These results suggest that sensory auditory processing in musicians is not only a fine tuning of universal abilities, but is also qualitatively more advanced than in nonmusicians. In addition, the relationship between the auditory change-detection function and perception is examined. It is shown that, contrary to the generally accepted view, MMN elicitation does not necessarily correlate with perception. The outcome of the auditory change-detection function can be implicit and the implicit knowledge of the sound structure can, after training, be utilized for behaviorally correct intuitive sound detection. These results illustrate the automatic character of the sensory change detection function.Kuulojärjestelmä analysoi akustisia tapahtumia jäsentääkseen meitä ympäröiviä ääniä. Kuulohavaintoon liittyvät kyvyt eivät ole staattisia, vaan niitä voidaan muokata harjoittelulla. Esimerkiksi viulisti pystyy erottamaan paljon pienempiä sävelkorkeuseroja kuin joku, jonka korva ei ole samalla tavalla kehittynyt harjoittelussa. Tästä syystä muusikot ovat mielenkiintoinen kohderyhmä kuulohavaintoon liittyvien kykyjen tutkimuksessa. Osa kuuloprosesseista tapahtuu automaattisesti, vaikka emme ole edes aina tietoisia meitä ympäröivistä äänistä. Joskus emme tarkkaile ääntä kuinnes se yhtäkkiä muuttuu. Toisinaan taas emme ole täysin tietoisia äänen muutostakaan, mutta tarkoittaako tämä sitä, että se ei voi vaikuttaa toimintaamme?
Tämän väitöskirjan tutkimuksissa aivosähkökäyrää eli EEG:tä mitattiin pään pinnalle kiinnitetyistä elektrodeista. EEG:llä mitatuista sähkökentistä voidaan päätellä, milloin kuulojärjestelmä on löytänyt satunnaisen muutoksen äänisarjassa, joka on muuten säännöllinen. Tämä ilmenee negatiivisena heilahduksena, jota kutsutaan MMN-vasteeksi (engl. mismatch negativity). MMN-vaste syntyy, vaikka koehenkilöt eivät tarkkailisi ääniärsykkeitä, ja tästä syystä sitä voidaan käyttää kuulojärjestelmässä automaattisesti tapahtuvan äänten käsittelyn tutkimiseen.
Havaitsemme merkitystä yhdistämällä samankaltaisia ääniä ja erottamalla niitä erilaisista äänistä. Tätä kutsutaan ryhmittelyksi. Tämän väitöskirjan tulosten mukaan kuuloaineiston ryhmittelytoiminto on kehittyneempi muusikoilla kuin muilla. Väitöskirjassa myös näytetään, että muusikoiden löytää neljän äänen säännönmukaisu uden muille merkityksettöm ästä äänisarjasta. Tämä viittaa siihen, että osa kuuloprosesseista, joita käytetään musiikin jäsentämiseen, on automatisoitunut muusikoilla. Tämä on hyödyllistä prosessointiresurssien kannalta, sillä näin niitä jää korkeampien toimintojen käyttöön.
Tämän väitöskirjan viimeisessä tutkimuksessa tarkasteltiin automaattisen poikkeavuuden käsittelyn ja tietoisen havaitsemisen suhdetta. Tutkimus osoitti, että MMN-vasteen syntyminen ei välttämättä satu yhteen tietoisen havainnon kanssa. Vaikka aivot löysivät satunnaiset muutokset ääniärsykkeissä, koehenkilöt eivät tietoisesti havainneet muutoksia. Ero sen välillä, mitä aivot käsittelivät ja mitä ihmiset tietoisella tasolla havaitsivat, osoittaa, että koehenkilöillä oli implisiittistä tietoa äänten rakenteesta. Kun koehenkilöitä sitten harjoitettiin kuulemaan muutoksia esittämällä yhtäaikaisesti visuaalinen vihje, puolet heistä oppi löytämään satunnaiset muutokset, pystymättä kuitenkaan kertomaan, miten ne erosivat muista äänistä. Toisin sanoen, he pystyivät löytämään poikkeamat intuitiivisesti. Tulokset osoittavat, että implisiittistä tietoa voidaan hyödyntää oikeiden intuitiivisten päätösten tekemisessä.ei saavutettav
MMN or no MMN: no magnitude of deviance effect on the MMN amplitude
No full textBased on results showing that the “deviant‐minus‐standard” estimate of the mismatch negativity (MMN) amplitude increases with increasing amounts of deviance, it has been suggested that the MMN amplitude reflects the amount of difference between the neural representations of the standard and the deviant sound. However, the deviant‐minus‐standard waveform also includes an N1 difference. We tested the effects of the magnitude of deviance on MMN while minimizing this N1 confound. We found no significant magnitude of deviance effect on the genuine MMN amplitude. Thus we suggest that the average MMN amplitude does not reflect the difference between neural stimulus representations; rather it may index the percentage of detected deviants, each of which elicits an MMN response of uniform amplitude. These results are compatible with an explanation suggesting that MMN is involved in maintaining a neural representation of the auditory environment.Vo
Pavlovian conditioning-induced hallucinations reduce MMN amplitudes for duration but not frequency deviants
No full text2023 Acuerdos transformativos CRUEThe mismatch negativity (MMN) is an evoked potential that indexes auditory regularity violations. Since the 90's, a reduced amplitude of this brain activity in patients with schizophrenia has been consistently reported. Recently, this alteration has been related to the presence of auditory hallucinations (AHs) rather than the schizophrenia diagnostic per se. However, making this attribution is rather problematic due to the high heterogeneity of symptoms in schizophrenia. In an attempt to isolate the AHs influence on the MMN amplitude from other cofounding variables, we artificially induced AHs in a non-clinical population by Pavlovian conditioning. Before and after conditioning, volunteers (N = 31) participated in an oddball paradigm that elicited an MMN. Two different types of deviants were presented: a frequency and a duration deviant, as the MMN alteration seems to be especially present in schizophrenia with the latter type of deviant. Hence, this pre-post design allowed us to compare whether experiencing conditioning-induced AHs exert any influence on MMN amplitudes. Our results show that duration-deviant related MMN reductions significantly correlate with the number of AHs experienced. Moreover, we found a significant correlation between AHs proneness (measured with the Launay-Slade Hallucination Extended Scale) and the number of AHs experienced during the paradigm. In sum, our study shows that AHs can be conditioned and exert similar effects on MMN modulation in healthy participants as has been reported for patients with schizophrenia. Thus, conditioning paradigms offer the possibility to study the association between hallucinations and MMN reductions without the confounding variables present in schizophrenia patients.Fundación "la Caixa"Depto. de Psicología Experimental, Procesos Cognitivos y LogopediaFac. de PsicologíaTRUEpubAPC financiada por la UC
MMN
No full textData files and analysis scripts for the MMN, elicited using a passive auditory oddball paradig
MMN
No full textData files and analysis scripts for the MMN, elicited using a passive auditory oddball paradig
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