Neuronal activity of monolingual and bilinguals to environmental sounds and words that are semantically related to them were studied using the mismatch negativity (MMN) component of event-related potentials. MMN was expected to reflect the language selection process in bilinguals on the bases of semantics and phonology. In this regard, as lexical stimuli, interlingual homophones ‘car’ and ‘kar’ (snow) were presented together with semantically related environmental sounds in a passive auditory oddball paradigm. The lexical stimuli were recorded by a native English speaker. Three Turkish-English late bilinguals and one native English speaker participated in the study. An early MMN was elicited in both groups with a distribution over the fronto-central and central areas across the scalp with highest peak amplitude at -2.5 with a 113 ms latency. This response indicates that participants of the study were sensitive to the acoustic changes in two different types of stimuli. The further investigation of the interplay between environmental sounds and semantics displayed no conclusive result due to lack of data. Finally, the brain responses gathered from the bilinguals were not enough to draw a conclusion. Whether the bilinguals were sensitive to the sub-phonemic cues in the presented auditory lexical stimuli or not were inconclusive. / Neuronal aktivitet av en- och tvåspråkiga till miljöljud och ord som är semantiskt relaterade till dem studerades med hjälp av Mismatch Negativity (MMN) komponent av event-relaterade potentialer. MMN förväntades spegla språkvalsprocessen i tvåspråkiga baserad på semantik och fonologi. I detta avseende presenterades interlingual-homofoner ’car’ (bil) och ’kar’ (snö) som lexikala stimuli tillsammans med semantiskt besläktade miljöljud i ett passivt auditivt oddball paradigm. De lexikala stimuli spelades in av en modersmålstalare av engelska. Tre turkiska-engelska sena tvåspråkiga och en modersmålstalare av engelska deltog i studien. En tidig MMN framkallades i båda grupperna med en fördelning över de främre central- och centrala områdena över skalp med amplitud vid -2,5 med 113 ms latens. Detta indikerar att deltagarna var sensitiva till de akustiska förändringarna mellan de två olika typerna av stimuli. Den vidare undersökningen av samspelet mellan miljöljud och semantik visade inget avgörande resultat. Dessutom, var det också ett inkonklusivt resultat som handlade om att huruvida tvåspråkiga deltagarna använde subfonemiska signalerna i de presenterade auditiva lexikala stimuli eller inte.

Skillnader i morfologisk komplexitet mellan språk har inte fått mycket fokus i forskningen kring neural bearbetning av morfologisk information. Trots detta har slutsatser dragits gällande böjningsmorfologi argumenterande för en skild bearbetning baserat på regelbundenhet, dvs. dekompositionell och holistisk bearbetning av regelbundna och oregelbundna böjningar respektive. För att tillföra forskningen en större morfologisk komplexitet och för att undersöka relationen mellan det kontinuerliga regelbundenhetspektrat och dikotomin av dekompositionell-holistisk bearbetning, undersökte denna uppsats den neurala bearbetningen av aspektböjning i modern grekiska, ett språk med hög grad av komplex böjningsmorfologi. Den tidiga auditiva ERP-komponenten MMN användes för att undersöka detta genom exploatering av dess påvisade relation till långtidsminnet genom att återspegla högre språkliga processer så som syntaktisk (sMMN) och lexikal (lMMN) bearbetning. Resultaten visade två MMN pikar, en tidigare vid 120-175 ms och en senare vid 240-300 ms, vilka modulerades enligt en sMMN-elicitering för både regelbunden och oregelbunden aspektböjning. Dessa resultat talar för en dekompositionell bearbetning av oregelbunden aspektböjning genom svag suppletion (/vɣázo/ → /vɣálo/) och argumenterades indikera avsaknaden av nödvändig morfologisk regelbundenhet för en möjlig dekompositionell böjningsbearbetning. / Differences in morphological complexity between languages have not recieved much attention within the field of neural processing of morphological information. Conclusions have though been drawn regarding inflectional morphology, arguing for different processing of regular and irregular inflections, i.e. decompositional and holistic processing respectively. To provide the research with higher morphological complexity and to investigate the relationship between the continuous regularity spectra and the dichotomy of decompositional-holistic processing, this thesis investigated the neural processing of aspectual inflection in modern Greek, a highly inflected language with complex verbal morphology. The early auditory ERP-component MMN was used to investigate this by exploiting it's shown longterm memory connections, reflecting higher linguisic processes such as syntactic (sMMN) and lexical (lMMN) processing. Results showed two MMN peaks, one earlier at around 120-175 ms and one later at around 240-300 ms. The peaks were modulated according to an sMMN elicitation for both regular and irregular inflections. These results, speaking for a decompositional processing of a irregular verb by weak suppletion (/vɣázo/ → /vɣálo/), were argued to indicate a lack of necessity of morphological regularity for a decompositional processing of inflection.

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The human central auditory system can automatically extract abstract regularities from a variant auditory input. To this end, temporarily separated events need to be related. This study tested whether the timing between events, falling either within or outside the temporal window of integration (~350 ms), impacts the extraction of abstract feature relations. We utilized tone pairs for which tones within but not across pairs revealed a constant pitch relation (e.g., pitch of second tone of a pair higher than pitch of first tone, while absolute pitch values varied across pairs). We measured the mismatch negativity (MMN; the brain’s error signal to auditory regularity violations) to second tones that rarely violated the pitch relation (e.g., pitch of second tone lower). A Short condition in which tone duration (90 ms) and stimulus onset asynchrony between the tones of a pair were short (110 ms) was compared to two conditions, where this onset asynchrony was long (510 ms). In the Long Gap condition, the tone durations were identical to Short (90 ms), but the silent interval was prolonged by 400 ms. In Long Tone, the duration of the first tone was prolonged by 400 ms, while the silent interval was comparable to Short (20 ms). Results show a frontocentral MMN of comparable amplitude in all conditions. Thus, abstract pitch relations can be extracted even when the within-pair timing exceeds the integration period. Source analyses indicate MMN generators in the supratemporal cortex. Interestingly, they were located more anterior in Long Gap than in Short and Long Tone. Moreover, frontal generator activity was found for Long Gap and Long Tone. Thus, the way in which the system automatically registers irregular abstract pitch relations depends on the timing of the events to be linked. Pending that the current MMN data mirror established abstract rule representations coding the regular pitch relation, neural processes building these templates vary with timing.:Introduction; Materials and methods; Results; Discussion; Conclusion

A mismatch negativity response (MMN) and a new differential waveform were derived in an effort to evaluate a neural refractory or recovery effect in adult listeners. The MMN was elicited using oddball test runs in which the standard and deviant stimuli differed in frequency. To derive the differential waveform, the same standard and deviant stimuli were presented alone. MMN responses were obtained by subtracting the averaged responses to standards from the deviants. The differential waveforms were obtained by subtracting the averaged responses to standards presented alone from deviants presented alone. Scalp topography for the MMN and differential waveforms were similar. A significant (p Se obtuvo una respuesta de negatividad desigual (MMN) y una nueva onda ?diferencial? en un esfuerzo por evaluar un efecto neural refractario o de recuperación en sujetos adultos. La MMN fue generada utilizando cursos peculiares de prueba en los que el estimulo estándar y el alterado tenían frecuencias diferentes. Para derivar la onda diferencial, se presentaron el mismo estímulo estándar y el alterado en forma aislada. Las respuestas MMN se obtuvieron restando las respuestas promediadas estándar de las alteradas. Las formas de onda diferenciales se obtuvieron restando las respuestas promediadas a estímulos estándar presentados aisladamente, de los estímulos alterados presentados también en forma aislada. La topografía craneana de los MMN y las onda diferenciales fueron similares. Se encontraron correlaciones positivas y negativas significativas (p

[Truncated abstract] Some children with Specific Language Impairment (SLI) show poor performance on behavioural tasks designed to measure rapid auditory processing, such as the Repetition Test developed by Tallal and colleagues. Stemming from concerns about whether this task reflects higher-order, cognitive variables, this thesis sought to determine whether the performance deficits SLI children show were evident at the neurophysiological level, with minimal cognitive influences, such as attention, using paradigms designed to elicit the mismatch negativity (MMN) and late discriminative negativity (LDN). In the first two studies, a MMN paradigm, equivalent to the Repetition Test, was trialled with a group of 8 adults. In this paired paradigm, the second tone of a pair of pure tones ascending in frequency ('low'-'high') was occasionally replaced with a 'low' tone. The aim was to determine a 'long' and 'short' intra-pair interval (IPI) with which MMN was generated utilizing this paradigm and that were congruent with the Repetition Test findings (i.e., a long IPI at which SLI were able to perform the task, and a short IPI at which SLI children's performance was selectively impaired). In Study One, MMN to a within-pair frequency change was generated with the 30 ms IPI, but not the 700 ms IPI. The grouping parameters of the temporal window of integration (TWI) and temporal distinctiveness were considered less than optimal for the grouping of the pairs presented at 700 ms IPI for the pre-attentive system to register the within-pair frequency change. ... The frequency difference limens (DLs) of the SLI group were significantly higher than a group of 18 normally developing age- and intelligence-matched peers, but there was no significant difference between the groups in their performance on a control intensity discrimination task. The iii SLI group also showed poorer reading skills, yet frequency discrimination was related to oral language ability only. In the final study, MMN was measured to examine the pre-attentive neurophysiological basis of the SLI group's frequency discrimination deficit. Two frequency deviants that were just above each group's 75% DL on the frequency discrimination task were employed in a simple frequency change paradigm: 40 Hz difference for the control group, and 80 Hz difference for the SLI group. MMN and LDN were elicited in the group of 15 normally developing children to their 40 Hz suprathreshold frequency difference and to the 80 Hz difference. A significant MMN was not observed in the group of 13 SLI children to the 40 Hz difference, which was below their threshold level. However, despite discrimination at the behavioural level, MMN did not reach significance in the SLI group to their 80 Hz suprathreshold frequency difference, yet LDN was observed. MMN was larger in both groups for the 80 Hz difference. Furthermore, MMN and LDN amplitude to the suprathreshold deviants were predictive of both frequency and intensity DLs. These results suggested that SLI children have a pre-attentive neurophysiologically mediated insensitivity to small frequency differences, and that MMN (and LDN) to suprathreshold frequency deviants is a sensitive indicator of group discrimination differences and brain-behaviour relationships in children with and without SLI.

Examined was whether the mismatch negativity (MMN) varied predictably in response to changes in the direction of frequency-modulated tone glides and equivalent second formant transitions in vowels (e.g., /ɪ/ as in “bit” and /e/ as in “bate”). A novel stimulus presentation paradigm was designed to distinguish the MMN from the N1 component. 10 normal-hearing adults with no neurological diseases were recruited and presented stimuli via insert earphones while they watched a silent, subtitled movie. Event-related potentials (ERPs) were recorded from 128 scalp electrodes. The MMN was successfully distinguished from the N1, marking participants’ ability to discriminate vowel stimuli only. A significant early P2 component, which decreased in size with successive stimulus presentations, was also elicited for vowels only and is believed to reflect formant encoding. Discrepancies between vowel and tone results are discussed along with clinical implications and contributions to the fields of ERP and vowel research.

The present thesis employed event-related potentials, the minute responses of the brain, to examine the differences in processing of increases and decreases in auditory intensity. The manner in which intensity was manipulated (i.e., whether it represented physical or psychological change) varied across the studies of the thesis. Study 1 investigated the processing of physical intensity change during wakefulness and natural sleep. An oddball paradigm (80 dB standard, 90 dB increment, 60 dB decrement) was presented to subjects during the waking state and during sleep. The increment elicited a larger deviant-related negativity and P3a than the decrement in the waking state. During sleep, only the increment deviant continued to elicit ERPs related to the detection of change. The waking and sleeping findings support the notion that increases in intensity are more salient to an observer. Studies 2 and 3 of this thesis determined the degree to which this differential salience could be attributed to the fact that intensity increments result in increased activation of the change and transient detection systems while intensity decrements result in greater activation of only the change detection system. In order to address this question, an alternating intensity pattern was employed (HLHLHLHL) with deviants created by the repetition of a tone in the sequence (HLHLHHHL) that violated the expectancy for a higher (psychological decrements) or lower intensity tone (psychological increments). Because deviant stimuli were physically identical to preceding standards, this manipulation should not have led to increased output of the transient detection system (N1 enhancement), permitting isolation of the output of the change detection system (Mismatch Negativity, MMN). The findings of these studies indicated that psychological increments resulted in shorter latency and larger amplitude MMNs than psychological decrements and that these differences could not be explained by the physical differences between deviant stimuli or temporal integration. This thesis provides convincing evidence that stimuli representing increments in intensity result in faster and more robust change detection. Further, the increased salience of increment stimuli cannot be solely explained by the contribution of transient detector activation, as it persists even when deviance-related processing is isolated to the change detection system.

Auditiv mismatch negativity (MMN) är en neurologisk hjärnrespons som visar hur känslig hjärnan är för auditiva förändringar. Perceptuell load teorin argumenterar att krävande visuella sökuppgifter eliminerar auditiva distraktorer från att bearbetas i arbetsminnet. Syftet är att observera event-related potential (ERP) händelser för att se om avvikande ljud exkluderas under hög visuell belastning. Ett korsmodalt uppmärksamhetstest utfördes där deltagarna (N = 26) fick utföra en visuell sökuppgift med två svårighetsgrader samtidigt som de skulle ignorera tonfrekvenser som spelades upp i bakgrunden. Resultatet visade auditiv MMN-respons under både låg och hög visuell belastning. Det fanns ingen tydlig skillnad på MMN mellan låg och hög belastning. Hörselcortex registrerade en avvikande ton i oddball och att samma ton fanns i kontroll-upplägget. Argument för att distraktorer bearbetas under kontrollerad uppmärksamhet. Ytterligare studier med större stickprov och olika ljudfrekvenser, naturliga och icke naturliga, krävs för att se hur ljuden påverkar bearbetningsprocessen.

abstract: Childhood Apraxia of Speech (CAS) is a severe motor speech disorder that is difficult to diagnose as there is currently no gold-standard measurement to differentiate between CAS and other speech disorders. In the present study, we investigate underlying biomarkers associated with CAS in addition to enhanced phenotyping through behavioral testing. Cortical electrophysiological measures were utilized to investigate differences in neural activation in response to native and non-native vowel contrasts between children with CAS and typically developing peers. Genetic analysis included full exome sequencing of a child with CAS and his unaffected parents in order to uncover underlying genetic variation that may be causal to the child’s severely impaired speech and language. Enhanced phenotyping was completed through extensive behavioral testing, including speech, language, reading, spelling, phonological awareness, gross/fine motor, and oral and hand motor tasks. Results from cortical electrophysiological measures are consistent with previous evidence of a heightened neural response to non-native sounds in CAS, potentially indicating over specified phonological representations in this population. Results of exome sequencing suggest multiple genetic variations contributing to the severely affected phenotype in the child and provide further evidence of heterogeneous genomic pathways associated with CAS. Finally, results of behavioral testing demonstrate significant impairments evident across tasks in CAS, suggesting underlying sequential processing deficits in multiple domains. Overall, these results have the potential to delineate functional pathways from genetic variations to the brain to observable behavioral phenotypes and motivate the development of preventative and targeted treatment approaches. / Dissertation/Thesis / Doctoral Dissertation Speech and Hearing Science 2018