Innovative Processing Algorithms for Fetal Magnetoencephalographic Data

Fetale Magnetenzepahalographie (fMEG) ermöglicht die Untersuchung der Entwicklung des zentralen und des autonomen Nervensystems bei Feten ab der 20. Schwangerschaftswoche. Wie normale Magnetenzephalographie bei Erwachsenen und Kindern ist auch fMEG eine nicht-invasive Methode und in der Anwendung vollkommen harmlos für Mutter und Kind. Die magnetischen Sensoren sind hierbei um das Abdomen der schwangeren Frau angeordnet. Die gute räumliche und zeitliche Auflösung erlaubt es, mütterliche und fetale Magnetokardiogramme gleichzeitig mit der fetalen Hirnaktivität zu messen. Die Signale der fetalen Magnetoenzephalographie werden vor allem zur Messung von auditiven und visuellen ereignisbezogenen Hirnreaktionen oder der spontanen Hirnaktivität verwendet. Wichtige Fragen zum Entwicklungsprozess des fetalen Gehirns und des autonomen Nervensystems sowie der mütterliche Einfluss auf den metabolischen und kognitiven Zustand des Neugeborenen können durch die Analyse der fetalen Magnetoenzephalographie-Signale geklärt werden. Die Auswertung der fetalen Hirnaktivität birgt einige Herausforderungen, da die Signale der fetalen und mütterlichen Herzaktivität etwa 10-1000 mal stärker sind als das fetale Hirnsignal. Daher ist es zwingend erforderlich, die Herzaktivität der Mutter und des Fetus zu erkennen und zu entfernen, bevor die fetale Hirnaktivität analysiert wird. Die derzeit verwendeten Methoden für die Erkennung und Entfernung der Herzaktivität funktionieren für die meisten Datensätze zuverlässig, die Verarbeitung enthält jedoch einige manuelle Schritte, was das Ganze sehr zeitaufwändig macht. Darüber hinaus ist die Signal Redistribution beim Entfernen der Herzaktivität ein bekanntes Problem, welches es schwierig macht, die Hirnaktivität später zu identifizieren. Das Ziel dieser Arbeit war es, die Auswertung der fMEG Daten schneller, besser und trotzdem leicht handhabbar zu machen. In dieser Arbeit werden zwei neue vollautomatisierte Methoden zur Erkennung und Entfernung der Herzaktivität vorgestellt. Der vollautomatisierte R-Peak Erkennungsalgorithmus (FLORA) verbessert die R-Peak Erkennung, indem er die Vorteile der zuvor verwendeten Methoden kombiniert und erweitert. Der Algorithmus zur vollautomatisierten Subtraktion der Herzaktivität (FAUNA) verbessert die Signalqualität und vereinfacht die Erkennung der Hirnaktivität, ohne Redistribution. Die Zuverlässigkeit der Daten wird dadurch erhöht, da keine manuelle Auswahl getroffen werden muss. Die Kombination beider Methoden in einem Programm zur vollautomatisierten Verarbeitung für die fetale Magnetoenzephalographie (FAIRY) macht die Datenauswertung nun einfach und schnell. Damit wird die fMEG Datenverarbeitung auf die "Big Data"- und "Automated Science"-Ära vorbereitet. Des Weiteren wurde eine Studie über die autonome und zentralnervöse Reaktion von Feten und Neugeborenen auf die mütterliche Stimme (AURORA) mit den neuen Datenverarbeitungsmethoden durchgeführt. Die Ergebnisse zeigten eine reduzierte Bewegung der Feten zwischen der 26. und 32. Schwangerschaftswoche und eine niedrigere Herzfrequenz während der ersten 20 Sekunden der Stimulation in den letzten Schwangerschaftswochen, als Reaktion auf die mütterliche Stimme. Zusätzlich fanden wir eine höhere Amplitude der Gehirnreaktion als Reaktion auf eine fremde Frauenstimme bei Neugeborenen.Fetal magnetoencephalography (fMEG) facilitates the investigation of both the nature and development of the fetal central and autonomic nervous system, starting at 20 weeks of gestational age. Like magnetoencephalography in children and adults, fetal magnetoencephalography is a noninvasive method and therefore completely harmless for both the mother and the child. Magnetic sensors in fMEG devices are arranged around the abdomen of the pregnant woman. The good spatial and temporal resolution allows to measure maternal and fetal magnetocardiograms simultaneously with fetal brain activity. The fMEG signals are mainly used to measure the auditory and visual event-related brain responses or the spontaneous brain activity. Important questions concerning the developmental process of the fetal brain, as well as the maternal influence on the metabolic and cognitive state of the newborn, can be clarified by the analysis of fMEG signals. The evaluation of the fetal brain activity poses some challenges, as the signals of fetal and maternal heart activity are 10-1000 times stronger than the fetal brain signal. Therefore, it is mandatory to detect and remove the heart activity of both the mother and the fetus before analyzing the fetal brain activity. The currently used methods for this detection and removal work well for most datasets, but the processing includes numerous manual steps and is therefore very time consuming. Furthermore, signal redistribution is a problem with the current methods, which makes later detection of the fetal brain activity challenging. The aim of this work was to make the evaluation of fMEG data faster, better and nevertheless, easy to use. In this thesis two new fully-automated procedures for the detection and removal of the heart activity are presented. The fully automated R-peak detection algorithm (FLORA) improves R-peak detection by combining and extending the advantages of the previously used methods. The algorithm for the fully automated subtraction of heart activity (FAUNA) improves the signal quality and facilitates detection of brain activity without the problem of redistribution. Furthermore these methods lead to a higher reliability of the data analysis since no manual interventions are necessary. Combining both methods in a tool for fully automated processing for fetal magnetoencephalography (FAIRY) makes data evaluation now easy and fast. This prepares the processing of fMEG data for the era of "Big Data" and "Automated Science". Additionally a study about the fetal and neonatal autonomous and central nervous response to maternal voice (AURORA) was performed using the new data processing methods. The results showed a reduced movement of fetuses between 26 and 32 weeks of pregnancy and a lower heart rate during the fist 20 seconds of stimulation in the last weeks of pregnancy as a reaction to maternal voice. We additionally found a higher amplitude of the brain response to voice onset of a stranger female voice in newborns

A Melodic Contour Repeatedly Experienced by Human Near-Term Fetuses Elicits a Profound Cardiac Reaction One Month after Birth

Human hearing develops progressively during the last trimester of gestation. Near-term fetuses can discriminate acoustic features, such as frequencies and spectra, and process complex auditory streams. Fetal and neonatal studies show that they can remember frequently recurring sounds. However, existing data can only show retention intervals up to several days after birth.Here we show that auditory memories can last at least six weeks. Experimental fetuses were given precisely controlled exposure to a descending piano melody twice daily during the 35(th), 36(th), and 37(th) weeks of gestation. Six weeks later we assessed the cardiac responses of 25 exposed infants and 25 naive control infants, while in quiet sleep, to the descending melody and to an ascending control piano melody. The melodies had precisely inverse contours, but similar spectra, identical duration, tempo and rhythm, thus, almost identical amplitude envelopes. All infants displayed a significant heart rate change. In exposed infants, the descending melody evoked a cardiac deceleration that was twice larger than the decelerations elicited by the ascending melody and by both melodies in control infants.Thus, 3-weeks of prenatal exposure to a specific melodic contour affects infants 'auditory processing' or perception, i.e., impacts the autonomic nervous system at least six weeks later, when infants are 1-month old. Our results extend the retention interval over which a prenatally acquired memory of a specific sound stream can be observed from 3-4 days to six weeks. The long-term memory for the descending melody is interpreted in terms of enduring neurophysiological tuning and its significance for the developmental psychobiology of attention and perception, including early speech perception, is discussed

Bipedal steps in the development of rhythmic behavior in humans

We contrast two related hypotheses of the evolution of dance: H1: Maternal bipedal walking influenced the fetal experience of sound and associated movement patterns; H2: The human transition to bipedal gait produced more isochronous/predictable locomotion sound resulting in early music-like behavior associated with the acoustic advantages conferred by moving bipedally in pace. The cadence of walking is around 120 beats per minute, similar to the tempo of dance and music. Human walking displays long-term constancies. Dyads often subconsciously synchronize steps. The major amplitude component of the step is a distinctly produced beat. Human locomotion influences, and interacts with, emotions, and passive listening to music activates brain motor areas. Across dance-genres the footwork is most often performed in time to the musical beat. Brain development is largely shaped by early sensory experience, with hearing developed from week 18 of gestation. Newborns reacts to sounds, melodies, and rhythmic poems to which they have been exposed in utero. If the sound and vibrations produced by footfalls of a walking mother are transmitted to the fetus in coordination with the cadence of the motion, a connection between isochronous sound and rhythmical movement may be developed. Rhythmical sounds of the human mother locomotion differ substantially from that of nonhuman primates, while the maternal heartbeat heard is likely to have a similar isochronous character across primates, suggesting a relatively more influential role of footfall in the development of rhythmic/musical abilities in humans. Associations of gait, music, and dance are numerous. The apparent absence of musical and rhythmic abilities in nonhuman primates, which display little bipedal locomotion, corroborates that bipedal gait may be linked to the development of rhythmic abilities in humans. Bipedal stimuli in utero may primarily boost the ontogenetic development. The acoustical advantage hypothesis proposes a mechanism in the phylogenetic development

Pitch discrimination in optimal and suboptimal acoustic environments : electroencephalographic, magnetoencephalographic, and behavioral evidence

Pitch discrimination is a fundamental property of the human auditory system. Our understanding of pitch-discrimination mechanisms is important from both theoretical and clinical perspectives. The discrimination of spectrally complex sounds is crucial in the processing of music and speech. Current methods of cognitive neuroscience can track the brain processes underlying sound processing either with precise temporal (EEG and MEG) or spatial resolution (PET and fMRI). A combination of different techniques is therefore required in contemporary auditory research. One of the problems in comparing the EEG/MEG and fMRI methods, however, is the fMRI acoustic noise. In the present thesis, EEG and MEG in combination with behavioral techniques were used, first, to define the ERP correlates of automatic pitch discrimination across a wide frequency range in adults and neonates and, second, they were used to determine the effect of recorded acoustic fMRI noise on those adult ERP and ERF correlates during passive and active pitch discrimination. Pure tones and complex 3-harmonic sounds served as stimuli in the oddball and matching-to-sample paradigms. The results suggest that pitch discrimination in adults, as reflected by MMN latency, is most accurate in the 1000-2000 Hz frequency range, and that pitch discrimination is facilitated further by adding harmonics to the fundamental frequency. Newborn infants are able to discriminate a 20% frequency change in the 250-4000 Hz frequency range, whereas the discrimination of a 5% frequency change was unconfirmed. Furthermore, the effect of the fMRI gradient noise on the automatic processing of pitch change was more prominent for tones with frequencies exceeding 500 Hz, overlapping with the spectral maximum of the noise. When the fundamental frequency of the tones was lower than the spectral maximum of the noise, fMRI noise had no effect on MMN and P3a, whereas the noise delayed and suppressed N1 and exogenous N2. Noise also suppressed the N1 amplitude in a matching-to-sample working memory task. However, the task-related difference observed in the N1 component, suggesting a functional dissociation between the processing of spatial and non-spatial auditory information, was partially preserved in the noise condition. Noise hampered feature coding mechanisms more than it hampered the mechanisms of change detection, involuntary attention, and the segregation of the spatial and non-spatial domains of working-memory. The data presented in the thesis can be used to develop clinical ERP-based frequency-discrimination protocols and combined EEG and fMRI experimental paradigms.Kyky erottaa korkeat ja matalat äänet toisistaan on yksi aivojen perustoiminnoista. Ilman sitä emme voisi ymmärtää puhetta tai nauttia musiikista. Jotkut potilaat ja hyvin pienet lapset eivät pysty itse kertomaan, kuulevatko he eron vai eivät, mutta heidän aivovasteensa voivat paljastaa sen. Sävelkorkeuden erotteluun liittyvistä aivotoiminnoista ei kuitenkaan tiedetä tarpeeksi edes terveillä aikuisilla. Siksi tarvitaan lisää tämän aihepiirin tutkimusta, jossa käytetään nykyaikaisia aivotutkimusmenetelmiä, kuten tapahtumasidonnaisia herätevasteita (engl. event-related potential, ERP) ja toiminnallista magneettikuvausta (engl. functional magnetic resonance imaging, fMRI). ERP-menetelmä paljastaa, milloin aivot erottavat sävelkorkeuseron, kun taas fMRI paljastaa, mitkä aivoalueet ovat aktivoituneet tässä toiminnossa. Yhdistämällä nämä kaksi menetelmää voidaan saada kokonaisvaltaisempi kuva sävelkorkeuden erotteluun liittyvistä aivotoiminnoista. fMRI-menetelmään liittyy kuitenkin eräs ongelma, nimittäin fMRI-laitteen synnyttämä kova melu, joka voi vaikeuttaa kuuloon liittyvää tutkimusta. Tässä väitöskirjassa tutkitaan, kuinka sävelkorkeuden erottelu voidaan todeta aikuisten ja vastasyntyneiden vauvojen aivoissa ja kuinka fMRI-laitteen melu vaikuttaa kuuloärsykkeiden synnyttämiin ERP-vasteisiin. Tutkimuksen tulokset osoittavat, että aikuisen aivot voivat erottaa niinkin pieniä kuin 2,5 %:n taajuuseroja, mutta erottelu tapahtuu nopeammin n. 1000-2000 Hz:n taajuudella kuin matalammilla tai korkeammilla taajuuksilla. Vastasyntyneen vauvan aivot erottelivat vain yli 20 %:n taajuusmuutoksia. Kun taustalla soitettiin fMRI-laitteen melua, se vaimensi aivovasteita 500-2000 Hz:n äänille enemmän kuin muille äänille. Melu ei kuitenkaan vaikuttanut alle 500 Hz:n äänten synnyttämiin aivovasteisiin. Riippumatta siitä, esitettiinkö taustalla melua vai ei, äänilähteen paikan muutoksen synnyttämä ERP-vaste oli suurempi kuin äänenkorkeuden muutoksen synnyttämä vaste. Tämä väitöskirjatutkimus on osoittanut, että sävelkorkeuden erottelua voidaan tutkia tehokkaasti ERP-menetelmällä sekä aikuisilla että vauvoilla. Tulosten mukaan ERP- ja fMRI-menetelmien yhdistämistä voidaan tehostaa ottamalla kokeiden suunnittelussa huomioon fMRI-laitteen melun vaikutukset ERP-vasteisiin. Tutkimuksen aineistoa voidaan hyödyntää monimutkaisten sävelkorkeuden erottelua mittaavien kokeiden suunnittelussa mm. potilailla ja lapsilla

An acoustic gap between the NICU and womb: a potential risk for compromised neuroplasticity of the auditory system in preterm infants

The intrauterine environment allows the fetus to begin hearing low-frequency sounds in a protected fashion, ensuring initial optimal development of the peripheral and central auditory system. However, the auditory nursery provided by the womb vanishes once the preterm newborn enters the high-frequency (HF) noisy environment of the neonatal intensive care unit (NICU). The present article draws a concerning line between auditory system development and HF noise in the NICU, which we argue is not necessarily conducive to fostering this development. Overexposure to HF noise during critical periods disrupts the functional organization of auditory cortical circuits. As a result, we theorize that the ability to tune out noise and extract acoustic information in a noisy environment may be impaired, leading to increased risks for a variety of auditory, language, and attention disorders. Additionally, HF noise in the NICU often masks human speech sounds, further limiting quality exposure to linguistic stimuli. Understanding the impact of the sound environment on the developing auditory system is an important first step in meeting the developmental demands of preterm newborns undergoing intensive care

Brain regions and functional interactions supporting early word recognition in the face of input variability

Perception and cognition in infants have been traditionally investigated using habituation paradigms, assuming that babies' memories in laboratory contexts are best constructed after numerous repetitions of the very same stimulus in the absence of interference. A crucial, yet open, question regards how babies deal with stimuli experienced in a fashion similar to everyday learning situations-namely, in the presence of interfering stimuli. To address this question, we used functional near-infrared spectroscopy to test 40 healthy newborns on their ability to encode words presented in concomitance with other words. The results evidenced a habituation-like hemodynamic response during encoding in the left-frontal region, which was associated with a progressive decrement of the functional connections between this region and the left-temporal, right-temporal, and right-parietal regions. In a recognition test phase, a characteristic neural signature of recognition recruited first the right-frontal region and subsequently the right-parietal ones. Connections originating from the right-temporal regions to these areas emerged when newborns listened to the familiar word in the test phase. These findings suggest a neural specialization at birth characterized by the lateralization of memory functions: the interplay between temporal and left-frontal regions during encoding and between temporo-parietal and right-frontal regions during recognition of speech sounds. Most critically, the results show that newborns are capable of retaining the sound of specific words despite hearing other stimuli during encoding. Thus, habituation designs that include various items may be as effective for studying early memory as repeated presentation of a single word.European Research Council under European Union 269502 CONICYT-Chile Program PIA/BASAL FB0003 "Progetto strategico NEURAT" from the University of Padua CONICYT-Chile Program PAI/Academia 7913002

Longitudinal trajectories of electrophysiological mismatch responses in infant speech discrimination differ across speech features

Infants rapidly advance in their speech perception, electrophysiologically reflected in the transition from an immature, positive-going to an adult-like, negative-going mismatch response (MMR) to auditory deviancy. Although the MMR is a common tool to study speech perception development, it is not yet completely understood how different speech contrasts affect the MMR’s characteristics across development. Thus, a systematic longitudinal investigation of the MMR’s maturation depending on speech contrast is necessary. We here longitudinally explored the maturation of the infant MMR to four critical speech contrasts: consonant, vowel, vowel-length, and pitch. MMRs were obtained when infants (n = 58) were 2, 6 and 10 months old. To evaluate the maturational trajectory of MMRs, we applied second-order latent growth curve models. Results showed positive-going MMR amplitudes to all speech contrasts across all assessment points that decreased over time towards an adult-like negativity. Notably, the developmental trajectories of speech contrasts differed, implying that infant speech perception matures with different rates and trajectories throughout the first year, depending on the studied auditory feature. Our results suggest that stimulus-dependent maturational trajectories need to be considered when drawing conclusions about infant speech perception development reflected by the infant MMR

Towards Optimal Testing of Auditory Memory : Methodological development of recording of the mismatch negativity (MMN) of the auditory event-related potential (ERP)

The overlapping sound pressure waves that enter our brain via the ears and auditory nerves must be organized into a coherent percept. Modelling the regularities of the auditory environment and detecting unexpected changes in these regularities, even in the absence of attention, is a necessary prerequisite for orientating towards significant information as well as speech perception and communication, for instance. The processing of auditory information, in particular the detection of changes in the regularities of the auditory input, gives rise to neural activity in the brain that is seen as a mismatch negativity (MMN) response of the event-related potential (ERP) recorded by electroencephalography (EEG). --- As the recording of MMN requires neither a subject s behavioural response nor attention towards the sounds, it can be done even with subjects with problems in communicating or difficulties in performing a discrimination task, for example, from aphasic and comatose patients, newborns, and even fetuses. Thus with MMN one can follow the evolution of central auditory processing from the very early, often critical stages of development, and also in subjects who cannot be examined with the more traditional behavioural measures of auditory discrimination. Indeed, recent studies show that central auditory processing, as indicated by MMN, is affected in different clinical populations, such as schizophrenics, as well as during normal aging and abnormal childhood development. Moreover, the processing of auditory information can be selectively impaired for certain auditory attributes (e.g., sound duration, frequency) and can also depend on the context of the sound changes (e.g., speech or non-speech). Although its advantages over behavioral measures are undeniable, a major obstacle to the larger-scale routine use of the MMN method, especially in clinical settings, is the relatively long duration of its measurement. Typically, approximately 15 minutes of recording time is needed for measuring the MMN for a single auditory attribute. Recording a complete central auditory processing profile consisting of several auditory attributes would thus require from one hour to several hours. In this research, I have contributed to the development of new fast multi-attribute MMN recording paradigms in which several types and magnitudes of sound changes are presented in both speech and non-speech contexts in order to obtain a comprehensive profile of auditory sensory memory and discrimination accuracy in a short measurement time (altogether approximately 15 min for 5 auditory attributes). The speed of the paradigms makes them highly attractive for clinical research, their reliability brings fidelity to longitudinal studies, and the language context is especially suitable for studies on language impairments such as dyslexia and aphasia. In addition I have presented an even more ecological paradigm, and more importantly, an interesting result in view of the theory of MMN where the MMN responses are recorded entirely without a repetitive standard tone. All in all, these paradigms contribute to the development of the theory of auditory perception, and increase the feasibility of MMN recordings in both basic and clinical research. Moreover, they have already proven useful in studying for instance dyslexia, Asperger syndrome and schizophrenia.Tarkoituksenmukainen ääniympäristössä toimiminen, kuten ääniympäristön merkityksellisiin tapahtumiin suuntautuminen ja kielellinen kommunikointi edellyttävät ääniympäristön säännömukaisuuksien, ja näistä poikkeavien tapahtumien tarkkaavuudesta riippumatonta mallintamista ja jäsentämistä yhtenäiseksi havaintokokonaisuudeksi. Tällaisen esitietoisen kuuloinformaation käsittelyn, erityisesti ääniympäristöstä poikkeavien äänien havaitsemisesta syntyvä hermosolujen aktivoituminen näkyy aivosähkökäyrässä tapahtumasidonnaisena MMN-jännitevasteena. --- Koska MMN:n rekisteröiminen ei edellytä tutkittavalta tehtävän tekemistä tai ärsykkeiden aktiivista kuuntelemista, sen avulla voidaan tutkia sensorisen kuulomuistin toimintaa jo vauvaiästä vanhuuteen saakka. Perustutkimuksen lisäksi MMN:ää voidaan hyödyntää erilaisten aivoperäisten ja aivoihin vaikuttavien sairauksien ja tilojen, kuten lukihäiriön, ikääntymisen ja skitsofrenian tutkimuksessa. Viimeaikaiset tutkimukset osoittavatkin, että kuuloinformaation prosessointi MMN:llä tutkittuna on poikkeavaa erilaisissa aivosairauksissa kuten skitsofreniassa, mutta muuttuu myös kehityksen ja normaalin ikääntymisen myötä. Edelleen on osoitettu, että nämä kuuloinformaation prosessoinnin muutokset voivat ilmetä valikoivasti joillekin äänen piirteille (esim. äänen kesto tai taajuus) sekä vain joissakin yhteyksissä (esim. vain puheäänissä). Vaikka MMN-tutkimuksella onkin huomattavia etuja verrattuna behavioraalisiin menetelmiin, sen yleistymistä laajempaan käyttöön, erityisesti kliiniseen tutkimukseen ja diagnostiikkaan, jarruttaa MMN-rekisteröinnin suhteellinen hitaus. Tavallisesti MMN-rekisteröinti yhdelle äänen piirteelle vaatii n. 15 minuuttia, joten useamman äänen piirteen erottelun profiilin rekisteröiminen vie helposti tunnista useaankin tuntiin. Tässä väitöskirjatutkimuksessa tavoitteena oli kehittää MMN-rekisteröinnissä käytettävää koeasetelmaa siten, että rekisteröinti voitaisiin tehdä aiempaa nopeammin, mutta yhtä luotettavasti. Väitöskirjatutkimuksessa kehitettiin koeasetelmia, joilla voidaan rekisteröidä lyhyessä ajassa (noin 15 minuuttia viidelle eri äänen piirteelle) useiden äänten piirteiden ja erikokoisten äänimuutosten prosessoinnin profiilit sekä puheäänille että ei-puheäänille. Koska näillä koeasetelmilla saadaan tietoa kuuloinformaation prosessoinnista huomattavasti aikaisempaa lyhyemmässä ajassa, ne parantavat MMN:n käytettävyyttä erityisesti kliinisissä tutkimuksissa. Edelleen, lyhyt rekisteröintiaika mahdollistaa entistä kattavamman ja monipuolisemman kuvan muodostamisen tutkittavien erottelukyystä eri äänen piirteiden välillä. Korkea reliabiliteetti puolestaan tuo luotettavuutta erityisesti pitkittäistutkimuksiin ja puhekonteksti soveltuu erityisesti kielen ja sen häiriöiden kuten dysfasian ja afasian tutkimukseen. Kehitimme myös vielä näitäkin taloudellisemman koeasetelman, jossa MMN vaste rekisteröitiin uudella tavalla, ilman toistuvaa ääntä ja tämän osatutkimuksen tulos on merkittävä myös MMN:n ja kuuloinformaation prosessoinnin teorian kannalta. Kaiken kaikkiaan nämä väitöskirjatyössä kehitetyt koeasetelmat tuovat uutta tietoa kuuloinformaation käsittelystä, ja parantavat huomattavasti MMN-menetelmän käytettävyyttä sekä perus- että kliinisessä tutkimuksessa. On myös huomionarvoista, että näiden koeasetelmien on jo osoitettu olevan hyödyllisiä mm. lukihäiriön, Aspergerin syndrooman ja skitsofrenian tutkimuksessa

Prenatal Music Exposure Induces Long-Term Neural Effects

We investigated the neural correlates induced by prenatal exposure to melodies using brains' event-related potentials (ERPs). During the last trimester of pregnancy, the mothers in the learning group played the ‘Twinkle twinkle little star’ -melody 5 times per week. After birth and again at the age of 4 months, we played the infants a modified melody in which some of the notes were changed while ERPs to unchanged and changed notes were recorded. The ERPs were also recorded from a control group, who received no prenatal stimulation. Both at birth and at the age of 4 months, infants in the learning group had stronger ERPs to the unchanged notes than the control group. Furthermore, the ERP amplitudes to the changed and unchanged notes at birth were correlated with the amount of prenatal exposure. Our results show that extensive prenatal exposure to a melody induces neural representations that last for several months.Peer reviewe

Neural encoding of voice pitch and formant structure at birth as revealed by frequency-following responses

Detailed neural encoding of voice pitch and formant structure plays a crucial role in speech perception, and is of key importance for an appropriate acquisition of the phonetic repertoire in infants since birth. However, the extent to what newborns are capable of extracting pitch and formant structure information from the temporal envelope and the temporal fine structure of speech sounds, respectively, remains unclear. Here, we recorded the frequency-following response (FFR) elicited by a novel two-vowel, rising-pitch-ending stimulus to simultaneously characterize voice pitch and formant structure encoding accuracy in a sample of neonates and adults. Data revealed that newborns tracked changes in voice pitch reliably and no differently than adults, but exhibited weaker signatures of formant structure encoding, particularly at higher formant frequency ranges. Thus, our results indicate a well-developed encoding of voice pitch at birth, while formant structure representation is maturing in a frequency-dependent manner. Furthermore, we demonstrate the feasibility to assess voice pitch and formant structure encoding within clinical evaluation times in a hospital setting, and suggest the possibility to use this novel stimulus as a tool for longitudinal developmental studies of the auditory system