More efficient formation of longer-term representations for word forms at birth can be linked to better language skills at 2 years

Infants are able to extract words from speech early in life. Here we show that the quality of forming longer-term representations for word forms at birth predicts expressive language ability at the age of two years. Seventy-five neonates were familiarized with two spoken disyllabic pseudowords. We then tested whether the neonate brain predicts the second syllable from the first one by presenting a familiarized pseudoword frequently, and occasionally violating the learned syllable combination by different rare pseudowords. Distinct brain responses were elicited by predicted and unpredicted word endings, suggesting that the neonates had learned the familiarized pseudowords. The difference between responses to predicted and unpredicted pseudowords indexing the quality of word-form learning during familiarization significantly correlated with expressive language scores (the mean length of utterance) at 24 months in the same infant. These findings suggest that 1) neonates can memorize disyllabic words so that a learned first syllable generates predictions for the word ending, and 2) early individual differences in the quality of word-form learning correlate with language skills. This relationship helps early identification of infants at risk for language impairment.Peer reviewe

Rhythmic structure facilitates learning from auditory input in newborn infants

Rhythm and metrical regularities are fundamental properties of music and poetry - and all of those are used in the interaction between infants and their parents. Music and rhythm perception have been shown to support auditory and language skills. Here we compare newborn infants' learning from a song, a nursery rhyme, and normal speech for the first time in the same study. Infants' electrophysiological brain responses revealed that the nursery rhyme condition facilitated learning from auditory input, and thus led to successful detection of deviations. These findings suggest that coincidence of prosodic cue patterns and to-be-learned items is more important than the format of the input. Overall, the present results support the view that rhythm is likely to create a template for future events, which allows auditory system to predict prospective input and thus facilitates language development.Peer reviewe

Koehenkilöiden välisten korrelaatioiden laskeminen elokuvakatselun aikana kerätystä MEG-datasta

Inter-subject correlation (ISC) is a measure for shared brain activity between subjects. ISC method is a data-driven approach that has been widely exploited to study brain responses to natural stimuli using functional magnetic resonance imaging (fMRI) but only scarcely utilizing magnetoencephalography (MEG). Natural stimuli are often too complex to be modelled explicitly but they are very useful in probing higher cognitive processes such as those supporting social interaction. The inter-subject correlation method was used in this Thesis to analyze MEG recordings of eight movie spectators. ISCs were assessed from the envelopes of the MEG signals in four frequency ranges (8--12, 14--22, 26--40 and 60--85 Hz) and from the steady-state response elicited by the 24-Hz frame rate of the movie. Correlations were calculated at source level from time courses obtained with minimum-norm estimate (MNE). Statistically significant correlations up to 0.22 plusminus 0.03 were found. They occurred mainly in early visual, motor, and somatosensory cortices.Koehenkilöiden välinen korrelaatio (ISC) on eräs tunnusluku sille, kuinka samankaltaista koehenkilöiden aivotoiminta on. Aineistolähtöisenä menetelmänä koehenkilöiden välisten korrelaatioiden tarkastelu sopii luonnollisista koeasetelmista kerättävän datan analysointiin, sillä se ei tarvitse tietoa ärsykkeistä. Luonnolliset ärsykkeet ovat otollisia tutkittaessa monimutkaisia kognitiivisia toimintoja, kuten esimerkiksi muistia tai sosiaalista kanssakäymistä, mutta usein liian monisyisiä mallinnettaviksi täsmällisesti. Koehenkilöiden välisten korrelaatioiden laskeminen on laajasti käytössä toiminnallista magneettiresonanssikuvantamista (fMRI) hyödyntävissä tutkimuksissa, mutta magnetoenkefalografialla (MEG) mitattuun dataan sitä on sovellettu vain muutaman kerran. Tässä diplomityössä koehenkilöiden välisiä korrelaatioita käytettiin kahdeksalta elokuvaa katsoneelta koehenkilöltä MEG:lla mitattujen aivovasteiden analysointiin. Korrelaatiot laskettiin neljällä eri taajuuskaistalla (8--12 Hz, 14--22 Hz, 26--40 Hz and 60--85 Hz) MEG-signaalien verhokäyristä, sekä lisäksi elokuvan 24 Hz:n kuvataajuuteen liittyvästä näköaivokuoren jatkuvasta vasteesta. Korrelaatiot selvitettiin lähdepisteittäin aivokuorelle miniminormimenetelmällä estimoiduista tunnusluvuista. Suurimmat tilastollisesti merkittävät korrelaatiot (jopa 0.22 plusminus 0.03) löydettiin pääasiallisesti varhaisilta näkö-, liike- ja tuntoaivokuorilta