Browsing by Subject "MMN"

Objectives. The aim of the current study was to explore whether there is an association between phonological processing and neural auditory discrimination in 5–6-years-old children. Phonological processing is defined by the ability to recognize and modulate small units of words, like phonemes. Neural auditory discrimination is defined by brain's automatic and preconscious ability to discriminate changes in auditory stimuli. Both phonological processing and neural auditory discrimination are important factors in the language development and deficits in those factors are known to be related to many language impairments. Single studies have reported an association between phonological processing and neural auditory discrimination but this theme is not well studied. In addition to group differences, we also studied differences in the ability to discriminate different sound deviants. Methods. The sample consisted of 38 children, whose mean age was 5 years and 10 months. The study was executed by dividing children into two groups by Nepsy-II phonological processing scores and comparing these two groups with the amplitudes of the brain's mismatch negativities (MMN) and late discriminative negativities (LDN). The comparison was made with repeated measures analysis of variance. Brain's event-related potentials were recorded with multifeature-paradigm in which the stimuli were modulated by vowel, consonant, duration of the vowel, intensity and frequency. Results and conclusions. The results of this current study demonstrate that differences in the phonological processing can be seen in the neural auditory discrimination. Both MMN- and LDN-potentials were stronger in those children, whose ability to process phonemes was better. In MMN-potentials the group difference was only seen in frequency, vowel and consonant deviants, whereas in LDN-potentials group differences were seen across all deviant types. In this study the phonological processing seems to be associated particularly to stronger LDN-potentials, which can provide information about the cognitive processes related to LDN-potentials. No previous studies about the association between phonological processing and LDN-potentials are known to be done.

Aivoverenkiertohäiriö (AVH) on maailmanlaajuisesti merkittävimpiä kielen ja auditiivisen havaitsemisen vaikeuksien aiheuttajia. Viime vuosikymmeninä musiikin ja kielen harjoittamisen on havaittu edistävän aivoissa paitsi modaliteetin sisäistä (kieli–kieli, musiikki–musiikki) havaitsemista myös siirtymävaikutusta erityisesti musiikista kielen havaitsemiseen. Tämä Pro Gradu -tutkielma selvitti äänikirjojen ja musiikin kuuntelun vaikutuksia varhaiseen puheen ja musiikin havaitsemiseen ensimmäisestä aivohalvauksesta toipuvissa aivoissa. Kontrolloituun tutkimusasetelmaan kuului kaksi interventioryhmää, joista toinen kuunteli päivittäin äänikirjoja ja toinen musiikkia ensimmäisten kahden kuukauden aikana aivohalvaukseen sairastumisesta; kontrolliryhmä ei saanut kuunneltavaa materiaalia. Potilaiden (N = 55) varhaista puheen ja musiikin havaitsemista aivoissa mitattiin äänisarjassa poikkeavan tavun (puhe) ja soinnun (musiikki) magneettisella poikkeavuusnegativisuusvasteella (magnetic mismatch negativity, MMNm) akuuttivaiheessa sekä seurantamittauksissa kolme ja kuusi kuukautta aivohalvaukseen sairastumisesta. Magnetoenkefalografisten (MEG) vasteiden lähteet aivoissa paikannettiin erotuskäyrien miniminormiestimaateilla (MNE) potilaiden yksilöllisissä, rakenteellisiin magneettiresonanssikuviin (MRI) perustuvissa aivomalleissa. Vasteiden lähteet rajoitettiin kuuteen puheen ja musiikin havaitsemisen kannalta keskeiseen alueeseen (keskimmäinen ja alempi otsalohkopoimu, ylempi ja keskimmäinen ohimolohkopoimu sekä supramarginaalinen ja kulmapoimu). Ryhmä- ja leesion hemisfäärin interaktiot analysoitiin tilastollisesti toistomittausten varianssianalyysillä näillä alueilla. Lisäksi interaktiotulokset korreloitiin (Pearson) neuropsykologiseen kuntoutumiseen verbaalisen muistin, työmuistin, kielen ja musiikin havaitsemisen osa-alueilla aivovasteiden laajemman osallisuuden selvittämiseksi auditiivisessa tiedonkäsittelyssä. Tutkimuksessa havaittiin, että äänikirjojen kuuntelu tehosti varhaista kielen havaitsemista vasemmanpuoleisilla otsalohkon alueilla kontrolliryhmään verrattuna; MMNm:n lateralisoituminen vasemmalle ilmeni kolme kuukautta aivohalvaukseen sairastumisesta ja oli lisäksi yhteydessä verbaalisen muistin paranemiseen äänikirjaryhmällä. Musiikin havaitseminen puolestaan herätti MMNm- ja P3a-komponentin yhdistelmän, jonka amplitudi vasemmalla alemmalla otsalohkopoimulla korreloi negatiivisesti työmuistin ja verbaalisen muistin paranemiseen kuusi kuukautta aivohalvaukseen sairastumisesta. Musiikin kuuntelu paransi suoriutumista, kun äänikirjojen kuuntelu oli yhteydessä kasvavaan amplitudiin ja heikkenevään työ- ja verbaaliseen muistiin; ilmiö todennäköisesti liittyy musiikin aikaansaamaan aktivaation levittäytymiseen aivoissa. Yhdessä tulokset viittaavat siihen, että äänikirjojen kuuntelu voi kehittää varhaista auditiivista havaitsemista kielimodaliteetin sisällä, joskaan se ei suoraan tue myöhempää, tarkkaavuuteen ja/tai musiikkimodaliteettiin liittyvää havaitsemista. Musiikin kuuntelu sen sijaan ei tue varhaista puheen havaitsemista suoraan, mutta voi edistää aivohalvauksen jälkeisiä plastisia muutoksia havaitsemisen ja verbaalisen muistin kannalta edullisemmalla tavalla.

This study investigated the processing of morphologically complex words in early childhood. Words are morphologically complex if they consist of more than one morpheme, the minimal meaning-bearing units of language. Previous studies indicate that there are two distinct routes used in the processing of morphologically complex words. Some words are stored in memory holistically and processed through these full-form memory traces. Other words are decomposed into their constituent morphemes, with morphemes and rules guiding their use forming the basis of processing. Research with adults has indicated that derivations are processed through their full-form memory traces, while inflections are decomposed into their constituent morphemes. However, research on neural mechanisms of morphological processing in early childhood is still missing. This study aimed to investigate whether children process morphologically complex words in a similar fashion to adults. Twelve 3–4-year-old Finnish-speaking children with normal language development took part in the study. Event-related potentials were extracted from the 64-channel EEG data. The focus was on mismatch negativity (MMN), which is associated with, among other things, automatic processing of language. Activation of full-form memory traces and syntactic processing tend to elicit distinct patterns of MMN responses. Moreover, the MMN has recently been used to demonstrate differences between processing of derivations and inflections. Inflected pseudowords elicited stronger MMN responses than real inflected words. This pattern of MMN responses is typical of syntactic processing. Therefore, the results indicate that inflections were processed syntactically, via morphological decomposition. In contrast to previous studies with adults, no difference was observed between MMN responses to derivations and inflections. Overall, these results suggest that children process inflections but not derivations in an adult-like manner. This can be taken as evidence for early development of syntactic processing and slower, more experience-dependent development of full-form memory traces

Aim of study. The aim of this study was to determine how the processing of pitch cues in spoken words is affected by listeners' native language. In previous studies, listeners' have shown a better sensitivity to acoustic features that are linguistically relevant in the native language. It has also been shown that the processing of pitch information is lateralized to the left hemisphere when the information is linguistically distinctive and lateralized to the right hemisphere when it is not carrying linguistically relevant information. The processing of lexical pitch has been shown to be language specific. Pitch is lexically discriminating in Estonian, but not in Finnish. Therefore, native speakers of Estonian were hypothesized to show a better sensitivity to changes in pitch than the native speakers of Finnish. They were also hypothesized to show a lateralization to the left when processing linguistically discriminating changes in pitch. Methods. 12 native speakers of Estonian and 12 native speakers of Finnish participated in the study. Mismatch negativity (MMN) components of event-related potentials (ERP) were measured with electroencephalography (EEG). Stimuli consisted of Estonian words, which showed differences in duration and pitch. Results and conclusions. Scalp maps of neural activation suggested a larger sensitivity for small changes in pitch for the Estonian group, as well as a tendency towards lateralization of the processing of pitch cues to the left hemisphere for the Estonian group, and to the right for the Finnish group. These observations were supported by a significant interaction effect between language group, lateralization, and stimulus type. However, further pairwise comparisons were only marginally significant. Due to large variation in the Estonian group, the group was split based on geographical background information, since the use of pitch cue has been shown to vary regionally in Estonia. This analysis indicated regional variation in the processing of the pitch cue; the western Estonian group showed lateralization to the left hemisphere while processing stimuli with a small change in pitch. The findings of this study are in line with previous studies, showing that the native language affects the processing of pitch. It also suggests that the local language variety has an impact on these processes.

Objectives. The aim of this study was to examine with electroencephalography (EEG) the associations between speech-sound elicited mismatch negativity (MMN) and late discriminative negativity (LDN) and pre-reading skills. Exploring the neural base of pre-reading skills will benefit the development of interventions for reading difficulties. It was hypothesized that left-lateralized MMNs and LDNs are elicited by all changes and larger and left-lateralized responses are linked with better pre-reading skills. Children with dyslexia risk were assumed to have poorer pre-reading skills and their responses were assumed to be smaller and more right-lateralized than in controls. Methods. Twenty-three children (of whom 16 with dyslexia risk) participated in an assessment of language abilities and EEG recording around the age of four years seven months. MMN and LDN were recorded for vowel, phoneme duration and frequency changes occurring in the second syllable of the standard stimulus (/tata/). The Repeated-measures analyses of covariance and the correlation analyses were applied to examine the relationship between MMN and LDN amplitudes, scalp distributions and phonological awareness, rapid automatized naming (RAN), verbal short-term memory, letter knowledge and a parent’s evaluation of pre-reading skills. The effects of risk status on MMN and LDN responses and pre-reading skills were investigated with the Repeated-measures and the One-way analyses of variance. Results. MMNs in the right hemisphere for consonant duration and vowel change and LDNs for all changes were statistically significant. LDN for vowel duration change was associated with RAN, and LDN for large frequency change was associated with letter knowledge so that the responses were larger in children performing better. LDN for vowel change was larger in children with poor letter knowledge and RAN, and LDN for small frequency change was larger in children performing poorly in RAN. Children performing poorly in RAN had right-lateralized MMNs, whereas children performing better had larger amplitudes mainly in the left hemisphere. Dyslexia risk had no effect on MMNs, LDNs or pre-reading skills. Conclusions. Right-lateralized speech processing and possibly also difficulties of discriminating vowel and frequency changes are associated with poor reading skills. Strengthening the ability to discriminate and manipulate phonemes may be important when supporting reading skills, however this should be investigated with an intervention study.

Objectives: The mismatch negativity (MMN) is a component of event-related potential reflecting a process where violations of regularities in auditory input are detected pre-attentively. In commonly used oddball- paradigm a repetitive standard stimulus is infrequently replaced by a deviant stimulus. Auditory deviance elicits MMN even in the absence of focused attention to stimuli. Automaticity of the MMN process has been an object of controversy due to limitations in methods used in most studies. Object of this study was to examine if potential attentional effects (suppression / enhancement) on MMN are similar or different to auditory stimuli violating regularities either physically or abstractly. Another goal was to examine if commonly used video-watching task can sufficiently keep attention directed away from the stimuli. Methods: Auditory stimuli was presented in an oddball paradigm. In physical stimuli blocks the deviant stimuli were higher in frequency compared to that of the standards. In abstract stimuli blocks the standard stimuli were tone pairs ascending in frequency, and deviant stimuli were descending tone pairs. Direction of attention was modulated by three conditions where subject’s task was to a) play a computer game (Tetris) b) watch a silent movie or c) focus on listening the stimuli and press a button to softer target deviants. Physical and abstract stimuli blocks were presented in each condition. Results: Both physical and abstract deviants elicited significant MMN in all three conditions. Direction of attention modulated by different tasks didn’t have a significant effect on amplitude of MMN elicited by physical and abstract deviants. Attention didn’t have any different effect on MMN regardless if it was elicited by stimuli violating regularities either physically or abstractly. Conclusions: The results of this study support the interpretation of MMN reflecting an automatic, attention- independent process where violations of regularities in auditory input are detected. Watching a silent movie seemed to sufficiently direct attention away from stimuli. Therefore video condition can be used as a primary task in future studies as well. Sometimes using a computer game similar to Tetris can be preferable since it might better uphold the arousal level of the subject.

Background. Aphasia is a language disorder caused by brain damage that occurs in up to 40% of stroke survivors. People with aphasia (PWA) often experience abnormalities in learning, short-term memory, and auditory processing, which are interconnected with their language processing deficits. Rehabilitation can induce changes in the auditory processing of PWA, and those changes can be linked also to language recovery. Singing abilities can be preserved in aphasia, which enables enjoyable and sociable therapy models for aphasia. This electroencephalography (EEG) study set out to explore the effects of multimodal choir-singing intervention on the implicit auditory processing capacities of PWA, reflected by the mismatch negativity (MMN), and whether the effect is correlated with changes in communicational abilities and verbal learning. Methods. 34 PWA took part in a 16-week intervention, which comprised of choir singing, melodic intonation therapy and home training. Participants trained one of two novel songs during the intervention. Before and after the intervention, the participants’ brain responses were recorded with EEG, while they listened to modulated versions of the two novel songs, one of which was rehearsed during the intervention. In this passive oddball-design, the songs contained deviations in pitch and phonemes. Communicational abilities and verbal learning were also assessed before and after the intervention. Linear mixed models were used to analyze the change that occurred during the intervention in the MMN response for both trained and untrained songs. Those changes were correlated with changes in communication and learning. Results and conclusions. The intervention had a statistically significant effect on the MMN to phoneme deviations in the trained and untrained songs in the left frontotemporal area. The amplitude of the MMN to phoneme deviations in the trained song decreased, while the amplitude of the MMN to phoneme deviations in the untrained song increased. Furthermore, the attenuation of the MMN to the trained song was correlated with improvement in language performance. These results imply that singing intervention can affect implicit auditory processes in PWA, and that changes in those processes can be accompanied by improved communication abilities.

Objective: According to previous studies mood can affect several higher cognitive skills. Positive mood helps performing in several cognitive processes. However, implicit mechanisms of learning have not yet been studied. The current study examined effects of positive and negative mood on neural mechanisms of auditory learning. Event-related potentials (ERPs), especially mismatch negativity (MMN), were recorded in both mood states. MMNs were expected to be more negative in positive mood state which would reflect better learning of auditory similarities in positive mood state. Methods: Positive and negative mood was induced in a counterbalances order to all subjects with self-chosen music and congruent Velten-sentences. Induced mood was measured using POMS-A-questionnaire. Subjects were instructed to direct their attention to a silent movie while musical stream was played through earphones. Responses on deviants appearing on the musical stream were recorded. Subjects were divided into two groups. One group started with positive mood induction followed by negative mood induction and the other group did vice versa. Induced mood was mild and only lasted for a short period of time. Experiment ended up with positive mood induction for both groups. Differences in ERPs between positive and negative mood was analyzed with repeated-measures ANOVA. Results and conclusions: There was a significant difference in ERPs between positive and negative mood. Especially the ERPs for deviants were more negative in the negative mood than in the positive mood in the posterior medial parts of the scalp. Hence, mood affected processing of deviant tones. This refers to effect of mood on learning of similarities in auditory sequencies.