Prenatal sensory development

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Neurocognition of Major-Minor and Consonance-Dissonance

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Iän ja musiikkikoulutuksen vaikutukset länsimaisen musiikin sointujen aivoperustaan

Infants already demonstrate readiness for music processing. Although culture-specific music-processing skills are acquired through exposure to music, even in the absence of formal training, the processing of music sounds is known to be facilitated by music training from early on. Major vs. minor and consonance vs. dissonance categorisations have a central role in Western tonal music and are highly meaningful for Western listeners. However, their neural basis and its development have not been extensively studied. The present thesis examined the preattentive processing of Western music chord categorisations from infancy to adulthood by measuring event-related potentials (ERPs) of the electroencephalogram (EEG), using a mismatch negativity (MMN) paradigm. The effect of music expertise on their processing was studied in school-aged children and adults. In the MMN paradigm, minor chords, inverted major chords, and highly dissonant chords were presented infrequently as deviant sounds in the context of root form major chords. Since all chords were transposed to several frequency levels, the deviant chords introduced no new frequencies to the paradigm, and thus an MMN caused by simple physical deviance was prevented. The results demonstrate the facilitating effects of music expertise on Western music chord discrimination neurally in adults and school-aged children, and behaviourally in adults. Sensitivity to Western music chord categorisations, particularly consonance vs. dissonance, was evident already at birth. While there was no evidence of major vs. minor discrimination as indicated by MMN elicitation in school-aged children without music training, there was tentative evidence of it in newborn infants and non-musician adults. Only musician adults demonstrated sensitivity to root vs. inverted chords, indicating that the facilitating effect of music expertise on the neural processing of the chords grows with age and years of practice. The present thesis suggests that, building on early auditory skills, some implicit knowledge of Western music chord categorisations is acquired via exposure to music during development, without formal training. However, consistent neural representations of complex chord categories may require extensive amounts of formal music training.Jo vauvaikäisellä on valmiuksia kuulla ja muistaa musiikin keskeisiä elementtejä. Oman kulttuurin musiikin prosessointitaitoja omaksutaan edelleen kehityksen ja musiikille altistumisen myötä myös ilman runsasta musiikkikoulutusta. Musiikin harrastaminen muokkaa aivojen kuuloalueiden toimintaa ja tehostaa siten musiikkiäänten käsittelyä jo lapsuudessa. Duuri vs. molli ja tasasointisuus vs. riitasointisuus sisältävät vahvoja merkityksiä länsimaiselle kuulijalle. Silti niiden erottelua ja sen kehitystä ei ole kattavasti tutkittu. Tässä väitöskirjatyössä selvitettiin länsimaisen musiikin sointujen kuulonvaraista prosessointia vauvaiästä aikuisuuteen mittaamalla aivosähkökäyrän tapahtumasidonnaisia jännitevasteita, jotka syntyvät esitietoisesti, ilman keskittynyttä kuuntelua. Vasteiden avulla voidaan tutkia äänten erotteluvalmiuksia jo vastasyntyneillä vauvoilla, joilla on rajalliset kyvyt ilmaista havaintojaan. Lisäksi on mahdollista verrata toisiinsa musiikkia harrastavia ja harrastamattomia lapsia ja aikuisia siten, että ryhmien väliset erot esimerkiksi keskittymiskyvyissä tai motivaatiossa paneutua musiikilliseen tehtävään eivät vaikuta tuloksiin. Tulosten perusteella länsimaisen musiikin sointujen erottaminen on tehostunut musiikkia harrastavilla kouluikäisillä lapsilla ja vielä voimakkaammin aikuisilla muusikoilla. Jo vastasyntyneiden aivoissa ilmeni valmiutta erotella länsimaisen musiikin sointuja, etenkin tasasointisia ja riitasointisia sointuja. Kouluikäisistä musiikkia harrastavat lapset erottelivat esitietoisesti duuri- ja mollisointuja, kun taas musiikkia harrastamattomilla lapsilla ei ilmennyt näyttöä erotteluvalmiudesta. Siitä oli kuitenkin jonkinasteista näyttöä vastasyntyneillä sekä aikuisilla, joilla ei ollut runsaasti musiikkikoulutusta. Vain aikuiset muusikot erottelivat esitietoisesti sointukäännöksiä perusmuotoisista soinnuista, minkä perusteella musiikkikoulutuksen yhteys sointujen tehostuneeseen hermostolliseen prosessointiin näyttää kasvavan iän ja harrastusvuosien myötä. Tämän väitöskirjatyön perusteella kehityksen myötä tapahtuva altistuminen länsimaiselle musiikille ilman muodollista musiikkikoulutusta voi tukea kykyä erotella länsimaisen musiikin keskeisiä elementtejä kuten duuri- ja mollisointuja tai tasasointisia ja riitasointisia sointuja, mutta jo vauvan varhaiset kuulovalmiudet luovat pohjaa näiden elementtien prosessoinnille. Vakaiden edustusten syntyminen aivoissa monimutkaisille musiikin piirteille voi kuitenkin vaatia pitkäkestoista musiikkikoulutusta

Can very early music interventions promote at-risk infants’ development?

Music and musical activities are often a natural part of parenting. As accumulating evidence shows, music can promote auditory and language development in infancy and early childhood. It may even help to support auditory and language skills in infants whose development is compromised by heritable conditions, like the reading deficit dyslexia, or by environmental factors, such as premature birth. For example, infants born to dyslexic parents can have atypical brain responses to speech sounds and subsequent challenges in language development. Children born very preterm, in turn, have an increased likelihood of sensory, cognitive, and motor deficits. To ameliorate these deficits, we have developed early interventions focusing on music. Preliminary results of our ongoing longitudinal studies suggest that music making and parental singing promote infants' early language development and auditory neural processing. Together with previous findings in the field, the present studies highlight the role of active, social music making in supporting auditory and language development in at-risk children and infants. Once completed, the studies will illuminate both risk and protective factors in development and offer a comprehensive model of understanding the promises of music activities in promoting positive developmental outcomes during the first years of life.Peer reviewe

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.Peer reviewe

Musiikin oppimisen siirtovaikutuksia

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Distortion and Western music chord processing : an ERP study of musicians and nonmusicians

GUITAR DISTORTION USED IN ROCK MUSIC MODIFIES a chord so that new frequencies appear in its harmonic structure. A distorted dyad (power chord) has a special role in heavy metal music due to its harmonics that create a major third interval, making it similar to amajor chord. We investigated how distortion affects cortical auditory processing of chords in musicians and nonmusicians. Electric guitar chords with or without distortion and with or without the interval of the major third (i.e., triads or dyads) were presented in an oddball design where one of them served as a repeating standard stimulus and others served as occasional deviants. This enabled the recording of event-related potentials (ERPs) of the electroencephalogram (EEG) related to deviance processing (the mismatch negativity MMN and the attention-related P3a component) in an ignore condition. MMN and P3a responses were elicited in most paradigms. Distorted chords in a non-distorted context only elicited early P3a responses. However, the power chord did not demonstrate a special role in the level of the ERPs. Earlier and larger MMN and P3a responses were elicited when distortion was modified compared to when only harmony (triad vs. dyad) was modified between standards and deviants. The MMN responses were largest when distortion and harmony deviated simultaneously. Musicians demonstrated larger P3a responses than nonmusicians. The results suggest mostly independent cortical auditory processing of distortion and harmony in Western individuals, and facilitated chord change processing in musicians compared to nonmusicians. While distortion has been used in heavy rock music for decades, this study is among the first ones to shed light on its cortical basis.Peer reviewe

Newborn infants' auditory system is sensitive to Western music chord categories

Neural encoding of abstract rules in the audition of newborn infants has been recently demonstrated in several studies using event-related potentials (ERPs). In the present study the neural encoding of Western music chords was investigated in newborn infants. Using ERPs, we examined whether the categorizations of major vs. minor and consonance vs. dissonance are present at the level of the change-related mismatch response (MMR). Using an oddball paradigm, root minor, dissonant and inverted major chords were presented in a context of consonant root major chords. The chords were transposed to several different frequency levels, so that the deviant chords did not include a physically deviant frequency that could result in an MMR without categorization. The results show that the newborn infants were sensitive to both dissonant and minor chords but not to inverted major chords in the context of consonant root major chords. While the dissonant chords elicited a large positive MMR, the minor chords elicited a negative MMR. This indicates that the two categories were processed differently. The results suggest newborn infants are sensitive to Western music categorizations, which is consistent with the authors' previous studies in adults and school-aged children.Peer reviewe

Structural white matter connectometry of reading and dyslexia

Current views on the neural network subserving reading and its deficits in dyslexia rely largely on evidence derived from functional neuroimaging studies. However, understanding the structural organization of reading and its aberrations in dyslexia requires a hodological approach, studies of which have not provided consistent findings. Here, we adopted a whole brain hodological approach and investigated relationships between structural white matter connectivity and reading skills and phonological processing in a cross-sectional study of 44 adults using individual local connectome matrix from diffusion MRI data. Moreover, we performed quantitative anisotropy aided differential tractography to uncover structural white matter anomalies in dyslexia (23 dyslexics and 21 matched controls) and their correlation to reading-related skills. The connectometry analyses indicated that reading skills and phonological processing were both associated with corpus callosum (tapetum), forceps major and minor, as well as cerebellum bilaterally. Furthermore, the left dorsal and right thalamic pathways were associated with phonological processing. Differential tractography analyses revealed structural white matter anomalies in dyslexics in the left ventral route and bilaterally in the dorsal route compared to the controls. Connectivity deficits were also observed in the corpus callosum, forceps major, vertical occipital fasciculus and corticostriatal and thalamic pathways. Altered structural connectivity in the observed differential tractography results correlated with poor reading skills and phonological processing. Using a hodological approach, the current study provides novel evidence for the extent of the reading-related connectome and its aberrations in dyslexia. The results conform current functional neuroanatomical models of reading and developmental dyslexia but provide novel network-level and tract-level evidence on structural connectivity anomalies in dyslexia, including the vertical occipital fasciculus.Peer reviewe

Infant event-related potentials to speech are associated with prelinguistic development

Neural auditory processing and prelinguistic communication build the foundation for later language development, but how these two are associated is not well known. The current study investigated how neural speech processing is associated with the level and development of prelinguistic skills in 102 infants. We recorded event-related potentials (ERPs) in 6-months-olds to assess the neural detection of a pseudoword (obligatory responses), as well as the neural discrimination of changes in the pseudoword (mismatch responses, MMRs). Prelinguistic skills were assessed at 6 and 12 months of age with a parental questionnaire (Infant-Toddler Checklist). The association between the ERPs and prelinguistic skills was examined using latent change score models, a method specifically constructed for longitudinal analyses and explicitly modeling intra-individual change. The results show that a large obligatory P1 at 6 months of age predicted strong improvement in prelinguistic skills between 6 and 12 months of age. The MMR to a frequency change was associated with the concurrent level of prelinguistic skills, but not with the improvement of the skills. Overall, our results highlight the strong association between ERPs and prelinguistic skills, possibly offering opportunities for early detection of atypical linguistic and communicative development.Peer reviewe