6 research outputs found

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

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    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

    ICA-derived cortical responses indexing rapid multi-feature auditory processing in six-month-old infants

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    The abilities of infants to perceive basic acoustic differences, essential for language development, can be studied using auditory event-related potentials (ERPs). However, scalp-channel averaged ERPs sum volume-conducted contributions from many cortical areas, reducing the functional specificity and interpretability of channel-based ERP measures. This study represents the first attempt to investigate rapid auditory processing in infancy using independent component analysis (ICA), allowing exploration of source-resolved ERP dynamics and identification of ERP cortical generators. Here, we recorded 60-channel EEG data in 34 typically developing 6-month-old infants during a passive acoustic oddball paradigm presenting 'standard' tones interspersed with frequency-or duration-deviant tones. ICA decomposition was applied to single-subject EEG data. The best-fitting equivalent dipole or bilaterally symmetric dipole pair was then estimated for each resulting independent component (IC) process using a four-layer infant head model. Similar brain-source ICs were clustered across subjects. Results showed ERP contributions from auditory cortex and multiple extra-auditory cortical areas (often, bilaterally paired). Different cortical source combinations contributed to the frequency-and duration-deviant ERP peak sequences. For ICs in an ERP-dominant source cluster located in or near the mid-cingulate cortex, source-resolved frequency-deviant response N2 latency and P3 amplitude at 6 months-of-age predicted vocabulary size at 20 months-of-age. The same measures for scalp channel F6 (though not for other frontal channels) showed similar but weaker correlations. These results demonstrate the significant potential of ICA analyses to facilitate a deeper understanding of the neural substrates of infant sensory processing. (C) 2016 Elsevier Inc. All rights reserved

    ICA-derived cortical responses indexing rapid multi-feature auditory processing in six-month-old infants

    No full text
    The abilities of infants to perceive basic acoustic differences, essential for language development, can be studied using auditory event-related potentials (ERPs). However, scalp-channel averaged ERPs sum volume-conducted contributions from many cortical areas, reducing the functional specificity and interpretability of channel-based ERP measures. This study represents the first attempt to investigate rapid auditory processing in infancy using independent component analysis (ICA), allowing exploration of source-resolved ERP dynamics and identification of ERP cortical generators. We expect source-resolved ERP measures to provide reliable prediction of later language development. Here, we recorded 60-channel EEG data in 34 typically developing six-month-old infants during a passive acoustic oddball paradigm presenting 'standard' tones interspersed with frequency- or duration-deviant tones. ICA decomposition was applied to single-subject EEG data. The best-fitting equivalent dipole or bilaterally symmetric dipole pair was then estimated for each resulting independent component (IC) process using a four-layer infant head model. Similar brain-source ICs were clustered across subjects. Results showed ERP contributions from auditory cortex and multiple extra-auditory cortical areas (often, bilaterally paired). Different cortical source combinations contributed to the frequency- and duration-deviant ERP peak sequences. For ICs in an ERP-dominant source cluster located in or near the mid-cingulate cortex, source-resolved frequency-deviant response N2 latency and P3 amplitude at six months-of-age predicted vocabulary size at twenty months-of-age. The same measures for scalp channel F6 (though not for other frontal channels) showed similar but weaker correlations. These results demonstrate the significant potential of ICA analyses to facilitate a deeper understanding of the neural substrates of infant sensory processing

    Perinnöllisen lukivaikeusriskin yhteys vastasyntyneen aivojen kuuloerotteluvasteisiin

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    Lukivaikeudesta kärsivä lukee muuta väestöä hitaammin ja virhealttiimmin. Kehityksellinen lukivaikeus on perinnöllinen oppimisvaikeus, joka on yhdistetty aivojen rakennemuutoksiin ja puutteellisiin äänten erottelukykyihin. Lukivaikeutta ja sen perinnöllistä riskiä on tutkittu aivojen kuuloherätevasteilla vauvoista aikuisiin. Lukivaikeus on yhdistetty muutoksiin esimerkiksi kuuloerottelukykyä mittaavassa mismatch negativity -vasteessa (lyh. MMN). Lukivaikeudesta kärsivien aikuisten ja perinnöllisen riskin omaavien lasten ja vauvojen MMN-vasteiden on havaittu olevan voimakkuudeltaan verrokkiryhmän vasteita pienempiä. Verrokkien MMN-vaste kielellisiin ääniin painottuu lukivaikeusriskissä olevien vastetta enemmän pään vasemmalle puolelle. Äänten erottelukyvyn kuntouttamisen on havaittu parantavan luku- ja kirjoitustaitoja. Kuntoutus on tehokkainta jo ennen lukemaan opettelua, mutta varhaisista lukivaikeuden ennusmerkeistä on vasta vähän tietoa. Pro gradu -tutkimuksessa selvitettiin perinnöllisen lukivaikeusriskin yhteyttä vastasyntyneiden kuuloerottelukykyihin herätevastemittauksen avulla 38 vastasyntyneellä, joista puolet olivat verrokkeja. Riskiryhmässä vauvojen toisella vanhemmalla oli testein vahvistettu lukivaikeus. Vastasyntyneille soitettiin herätevastemittauksen aikana epäsanasta /ta-ta/ koostuvaa äänisarjaa. Epäsanan jälkimmäisessä tavussa oli satunnaisia äänen keston, korkeuden, ja vokaalin muutoksia. Koeasetelma sisälsi myös epäsanasta eroavia yllättäviä ääniä. Lopuksi vauvoille soitettiin vertailukoeasetelma, jonka avulla pyrittiin selvittämään, miten äänten akustinen vaihtelu vaikuttaa vasteisiin. Kuuloherätevasteet puheäänille olivat voimakkuudeltaan pieniä. Vokaalin keston ja äänenkorkeuden muutokset synnyttivät sekä lukiriski- että verrokkiryhmässä merkitsevät MMN-vasteet. Voimakkain MMN-vaste syntyi vokaalin keston muutokselle, ja tämä vaste näytti alkavan perinnöllisen riskin omaavassa ryhmässä myöhemmin kuin verrokeilla. Toistuvalle vakioäänelle ja äänenkorkeuden muutokselle syntyneet vasteet näyttivät olevan ryhmissä erilaisia, mutta nämä erot eivät saavuttaneet tilastollista merkitsevyyttä. Pelkkä akustinen vaihtelu ei vaikuttanut vasteiden voimakkuuteen. Sen sijaan vastasyntyneen sukupuoli, raskauden kesto ja syntymäpaino olivat yhteydessä kuuloherätevasteiden voimakkuuteen. Tulosten mukaan perinnöllinen lukivaikeusriski vaikuttaa jo vastasyntyneen kuuloerottelukykyihin, joten kuulokykyjen kuntouttamisen tutkiminen on perusteltua jo varhaisessa vaiheessa.Dyslexia affects reading speed and accuracy. Developmental dyslexia is a heritable learning disability related to structural changes in the brain and deficits in sound discrimination. Dyslexia and its’ genetic risk have been studied with auditory event-related potentials (ERPs) from babies to adults. Dyslexia has been associated with changes in the cortical change detection response called the mismatch negativity (MMN). Dyslexic adults and children elicit attenuated MMN responses compared to the control group. The controls’ MMN responses to speech sounds are more pronounced on the left hemisphere than the at-risk group’s responses. Interventions targeting the sound discrimination and phonological awareness have resulted in better reading and writing skills. Rehabilitation is most efficient already before school-age but research on early markers of dyslexia is still insufficient. We studied the relation between inherited dyslexia risk and newborn brain responses by recording ERPs from 38 babies. Half of them were controls. Newborns in the at-risk group had one parent with diagnosed dyslexia. During the ERP recordings we used a speech sound stream consisting of the repetitive pseudoword /ta-ta/. The latter syllable contained infrequent duration, frequency and vowel changes. The sound stream also contained distinct and surprising sounds. We also included a control paradigm to investigate how acoustic variance in the speech sounds affects the brain responses. The speech sound ERPs were small in amplitude. Duration and frequency changes elicited significant MMN responses in both the at-risk and control groups. The strongest MMN response in both groups was due to duration change. The onset of this MMN response seemed to be delayed in the at-risk group. The profiles for standard responses and frequency-MMN responses differed between the groups but these differences didn’t reach statistical significance. Acoustic variance had no effect on the MMN amplitude. Background factors including sex, duration of the pregnancy and birth weight correlated with the response amplitudes. Overall these results show that inherited dyslexia risk contributes to sound discrimination skills soon after birth. Hence studying auditory discrimination interventions at an early age is well-grounded

    Neuroimaging of endogenous lapses of responsiveness,

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    Attention lapses (ALs) and microsleeps (MSs) are complete lapses of responsiveness in which performance is completely disrupted for a short period of time, but consciousness is retained in the case of ALs. ALs are behaviourally different from MSs, as in an AL the eyes remain open whereas in a MS eyes are partially or completely closed. Both ALs and MSs can result in catastrophic consequences, especially in the transportation sector. Research over the past two decades has investigated the AL and MS phenomena using behavioural and physiological means. However, both ALs and MSs need further investigation to separate the different types of ALs physiologically, and to explore the neural signature of MSs in relation to normal sleep and drowsiness. Hence, the objective of this project was to understand the underlying physiological substrates of endogenous (internal) ALs and MSs which could potentially result in differentiating types of ALs and provide more understanding of MSs. Data from two previous Christchurch Neurotechnology Research Programme (NeuroTech™) studies (C and D) were combined resulting in a total of 40 subjects. During each session, subjects performed a 2-D continuous visuomotor tracking (CVT) task for 50 min (Study C) and 20 min (Study D). For each participant, tracking performance, eye-video, EEG, and fMRI were simultaneously collected. A human expert visually inspected the tracking performance and eye-video recordings to identify and categorize lapses of responsiveness for each participant. Participants performed the 2-D CVT task without interruptions. The repetitive nature of the task and the lack of a motivational factor made the task monotonous and fatiguing. As a result, it was more likely to introduce boredom leading to task-unrelated thoughts (TUTs), which divides attention between the task and the internal thoughts unrelated to the task, also fatigue which will introduce a trend of vigilance decrement over time. The project had hypotheses focusing on the changes in the brain’s activity compared to the baseline of good responsiveness tracking. We expected a decrease in dorsal attention network (DAN) activity during ALs due to a decoupling of attention from the external environment. Furthermore, we hypothesized that the ALs were due to involuntary mind-blanks. As such, we expected no change in default mode network (DMN) activity, as would have otherwise been expected if the ALs were due to mind-wandering. Functional connectivity (FC) of the brain was also investigated between the networks of interest which were the DMN, DAN, frontoparietal network (FPN), sensorimotor network (SMN), visual network (VSN), salience network (SN), eye-movement network (EMN), and working memory network (WMN), by analysing data from fMRI. EEG data were also used to perform analysis on ALs and MSs, by analysing changes in power in the delta, theta, alpha, beta, and gamma bands. Voxel-wise fMRI throughout the whole brain, group-ICA, haemodynamic response (HR) over the regions of interest (ROIs), and FC analyses were performed to reveal the neural signature during ALs. In voxel-wise analysis, a significant increase in activity was found in two regions: the dorsal anterior cingulate cortex (dACC) and the supplementary motor area (SMA). The group-ICA analysis did not show any significant results but did show a trend of increased activity in an independent component (IC) that was spatially correlated with SMN. Dynamic HR analysis was performed to further investigate findings from the voxel-wise analysis. Our results were not significant but there were strong trends of change. There was a trend of increased HR 7.5 s after the onset of the AL in the left intraparietal sulcus (IPS) of the DAN. There was also a decrease of 2.5 s before the onset of the AL in the right posterior parietal cortex (PPC) of the FPN. There was also an increase in the HR 5 s after the onset of the AL in the dACC of the SN. Finally, an increase in the HR 15 s before the onset of ALs in the left inferior parietal lobule (IPL) of the DMN is a major finding, as it is an indication that a lapse is about to happen. The HR analysis provided consistent findings with the voxel-wise analysis. FC analysis showed increases in FC within all networks of interest during the ALs. On looking at FC between networks, there was an increase in FC between the DMN and the FPN, no change between the DAN and the FPN, a decrease in FC between the SMN and the FPN, and an increase in FC between the FPN and the VSN. The EMN had an increased FC with the DMN, while it had both increases and decreases in FC with the DAN. There was also an increase in FC between the SN and the DAN, and no change between the SN and the DMN. Finally, a decrease in FC was found between the WMN and the DMN. These findings indicate an overlap between decoupling due to ALs and the process of recovery from ALs. The EEG analysis showed no significant change in the relative difference between average spectral power during ALs and their average baselines for any band of interest for ALs. During MSs, there was a significant increase in power relative to responsive baselines in the delta, theta, alpha, beta, and gamma bands. However, we could not be completely sure that all motion-related artefacts had been removed. Hence, we investigated this further by removing the effect of the global signal, which left only an increase in gamma activity, in addition to a trend of decreased activity in the alpha band. The significant increase in BOLD seen in the voxel-wise analysis is considered to represent the recovery of responsiveness following ALs. This was also seen in trends in group ICA and HR analyses. Overall, findings from the FC analysis show that, in addition to decoupling during ALs, and recovery from ALs, it is highly likely that the ALs during the 2-D CVT task were due to involuntary mind-blanks. This is supported by three major findings: (1) no significant increase in DMN activity in both voxel-wise and HR analyses, (2) the decrease in the HR in the FPN prior to the onset of the AL, and (3) the decrease in FC between the DMN and the WMN. This is further supported behaviourally by the short average duration of ALs (~ 1.7 s), in contrast to what would be likely during mind-wandering. Finally, the significant results from the EEG analysis of MSs, agreed with the literature in delta, theta, and alpha bands. However, increased power in beta and gamma bands was an important finding. We consider this increased high-frequency activity reflects unconscious ‘cognitive’ activity during a MS aimed at restoring consciousness after having fallen asleep during an active task. This highlights a key behavioural and physiological difference between MSs and sleep. Even after removing the effect of the global signal, we still believe that MSs and sleep are physiologically different in the recovery process. To summarize our key findings: (1) this is the first study to demonstrate that ALs during a continuous task are likely to be due to involuntary mind-blanks, (2) the increase in the HR in the DMN 15 s before the onset of AL could be a predictive signature of these lapses, and finally (3) MSs are physiologically different from sleep in terms of the recovery process. This project has improved our understanding of endogenous ALs and MSs and taken us a step closer to accurate detection/prediction systems which can increase prevention of fatal accidents
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