Brain Source Correlates of Speech Perception and Reading Processes in Children With and Without Reading Difficulties

Neural correlates in reading and speech processing have been addressed extensively in the literature. While reading skills and speech perception have been shown to be associated with each other, their relationship remains debatable. In this study, we investigated reading skills, speech perception, reading, and their correlates with brain source activity in auditory and visual modalities. We used high-density event-related potentials (ERPs), fixation-related potentials (FRPs), and the source reconstruction method. The analysis was conducted on 12–13-year-old schoolchildren who had different reading levels. Brain ERP source indices were computed from frequently repeated Finnish speech stimuli presented in an auditory oddball paradigm. Brain FRP source indices were also computed for words within sentences presented in a reading task. The results showed significant correlations between speech ERP sources and reading scores at the P100 (P1) time range in the left hemisphere and the N250 time range in both hemispheres, and a weaker correlation for visual word processing N170 FRP source(s) in the posterior occipital areas, in the vicinity of the visual word form areas (VWFA). Furthermore, significant brain-to-brain correlations were found between the two modalities, where the speech brain sources of the P1 and N250 responses correlated with the reading N170 response. The results suggest that speech processes are linked to reading fluency and that brain activations to speech are linked to visual brain processes of reading. These results indicate that a relationship between language and reading systems is present even after several years of exposure to print

PUHEEN HAVAINTO, KUULOJÄRJESTELMÄ JA AIVOJEN RYTMIT DYSLEKSIASSA

Dysleksia on kehityksellinen pulma lukemaan ja kirjoittamaan oppimisessa ja lukutaidon sujuvoitumisessa. Dysleksiaan liittyy myös muita pulmia esimerkiksi äänne- eli fonologisessa tietoisuudessa, kielellisessä muistissa, kyvyssä nimetä nopeasti tuttuja asioita ja kuulohavainnossa. Tämä katsausartikkeli keskittyy kuulohavainnon ja dysleksian välisiin yhteyksiin. Kuulotiedon käsittelyyn liittyvät pulmat ja lukihäiriö ovat olleet vilkkaan keskustelun aiheena jo pitkään johtuen melko ristiriitaisista löydöksistä. Meta-analyysi kuitenkin osoittaa, että jopa puolella heikoista lukijoista saattaa olla pulmaa äänen keston ja nousuaikojen havaitsemisessa sekä vähäisemmässä määrin taajuuksienhavainnossa. Vastaavasti äänen voimakkuuden havainnossa pulmiaei juurikaan esiinny. Kuulojärjestelmässä esiintyvien pulmien taustalla oleva mekanismi on edelleen selvittämättä. Uusi näkökulma mahdolliseen mekanismiin on auennut aivojen rytmien kautta. Aivojen aktiivisuus seuraa puheen tavutason rytmiä ja siten muokkaa aikaikkunoita, joissa havaitseminen on erityisen tarkkaa. Henkilöillä, joilla on dysleksia, aivojen aktivaatio saattaa seurata puhetta ja puheen rytmiä eri tavalla kuin tyypillisillä lukijoilla ja siten olla yhtenä tekijänä puheen havaitsemisen ja fonologisten pulmien taustalla.Avainsanat: aivot, dysleksia, kuulohavainto, puheKeywords: auditory perception, brain, dyslexia, speec

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

Review of Abnormal Self-Knowledge in Major Depressive Disorder

Background: Major depressive disorder (MDD) is an affective disorder that is harmful to both physical and mental health. Abnormal self-knowledge, which refers to abnormal judgments about oneself, is a core symptom of depression. However, little research has summarized how and why patients with MDD differ from healthy individuals in terms of self-knowledge.Objective: To gain a better understanding of MDD, we reviewed previous studies that focused on the behavioral and neurological changes of self-knowledge in this illness.Main Findings: On the behavioral level, depressed individuals exhibited negative self-knowledge in an explicit way, while more heterogeneous patterns were reported in implicit results. On the neurological level, depressed individuals, as compared with non-depressed controls, showed abnormal self-referential processing in both early perception and higher cognitive processing phases during the Self-Referential Encoding Task. Furthermore, fMRI studies have reported aberrant activity in the medial prefrontal cortex area for negative self-related items in depression. These results revealed several behavioral features and brain mechanisms underlying abnormal self-knowledge in depression.Future Studies: The neural mechanism of implicit self-knowledge in MDD remains unclear. Future research should examine the importance of others' attitudes on the self-concept of individuals with MDD, and whether abnormal self-views may be modified through cognitive or pharmacological approaches. In addition, differences in abnormal self-knowledge due to genetic variation between depressed and non-depressed populations remain unconfirmed. Importantly, it remains unknown whether abnormal self-knowledge could be used as a specific marker to distinguish healthy individuals from those with MDD.Conclusion: This review extends our understanding of the relationship between self-knowledge and depression by indicating several abnormalities among individuals with MDD and those who are at risk for this illness

Understanding developmental language disorder -The Helsinki longitudinal SLI study (HelSLI): A study protocol

BackgroundDevelopmental language disorder (DLD, also called specific language impairment, SLI) is a common developmental disorder comprising the largest disability group in pre-school-aged children. Approximately 7% of the population is expected to have developmental language difficulties. However, the specific etiological factors leading to DLD are not yet known and even the typical linguistic features appear to vary by language. We present here a project that investigates DLD at multiple levels of analysis and aims to make the reliable prediction and early identification of the difficulties possible. Following the multiple deficit model of developmental disorders, we investigate the DLD phenomenon at the etiological, neural, cognitive, behavioral, and psychosocial levels, in a longitudinal study of preschool children.MethodsIn January 2013, we launched the Helsinki Longitudinal SLI study (HelSLI) at the Helsinki University Hospital (http://tiny.cc/HelSLI). We will study 227 children aged 3–6 years with suspected DLD and their 160 typically developing peers. Five subprojects will determine how the child’s psychological characteristics and environment correlate with DLD and how the child’s well-being relates to DLD, the characteristics of DLD in monolingual versus bilingual children, nonlinguistic cognitive correlates of DLD, electrophysiological underpinnings of DLD, and the role of genetic risk factors. Methods include saliva samples, EEG, computerized cognitive tasks, neuropsychological and speech and language assessments, video-observations, and questionnaires.DiscussionThe project aims to increase our understanding of the multiple interactive risk and protective factors that affect the developing heterogeneous cognitive and behavioral profile of DLD, including factors affecting literacy development. This accumulated knowledge will form a heuristic basis for the development of new interventions targeting linguistic and non-linguistic aspects of DLD.<br /

Brain responses to changes in tone and speech stimuli in infants with and without a risk for familial dyslexia

Developmental dyslexia, a specific disorder of learning to read, is widely acknowledged as being often genetically transmitted, but as yet, little is known of the early precursors of the disorder. In the present study the brain electrical responses to changes in auditory oddball paradigms were studied both at birth and at the age of six months in a group of young infants from families with a genetic background of developmental dyslexia (at-risk group) and in a group of infants without such a background (control group). Both group differences and developmental features of event-related potentials (ERPs) were under focus. At birth, the ERPs to the deviating rare /ka/ stimuli with an interstimulus interval of 855 ms were different between the groups, but not with a shorter interval of 425 ms. At six months of age some differences between the groups were found in their responses to the frequent /kaa/ stimulus. At this age, more marked group differences were found in the ERPs to the duration change of a silence period, an acoustic cue for consonant lengths, embedded within a pseudoword (/ ata/ vs. / atta/). The results suggest, that the at-risk group differ from the control group both in the basic responsiveness to auditory/ speech stimuli and in the responses to changes in the temporal structure of speech stimuli, as well as in terms of how the stimulus presentation context affects the ERPs. The clearest developmental feature at birth was a waveform consisting of a long lasting positive deflection, which was generated by all deviant stimulus types, whether pure tones or speech stimuli differing in their temporal features. By the age of six months, this slow waveform pattern had been transformed into a wave complex with clearly distinguishable deflections, reflecting a more mature negative-positive-negative deflection structure. The responses to deviant stimuli were, typically still at this age, positively displaced in relation to those to the standard stimuli, suggesting maturational effects on early ERPs. Some evidence for an adult-like negatively displaced mismatch negativity (MMN) response was also found

Neural Processing of Congruent and Incongruent Audiovisual Speech in School-Age Children and Adults

Seeing articulatory gestures enhances speech perception. Perception of auditory speech can even be changed by incongruent visual gestures, which is known as the McGurk effect (e.g., dubbing a voice saying /mi/ onto a face articulating /ni/, observers often hear /ni/). In children, the McGurk effect is weaker than in adults, but no previous knowledge exists about the neural-level correlates of the McGurk effect in school-age children. Using brain event-related potentials, we investigated change detection responses to congruent and incongruent audiovisual speech in school-age children and adults. We used an oddball paradigm with a congruent audiovisual /mi/ as the standard stimulus and a congruent audiovisual /ni/ or McGurk A/mi/V/ni/ as the deviant stimulus. In adults, a similar change detection response was elicited by both deviant stimuli. In children, change detection responses differed between the congruent and the McGurk stimulus. This reflects a maturational difference in the influence of visual stimuli on auditory processing.Peer reviewe

A superconducting gravimeter for evaluation of groundwater changes in the field

textThe Superconducting Gravimeter (SG) is an extremely sensitive instrument that measures relative changes in gravity. It is based on the movement of a superconducting sphere levitated in a magnetic field created by current in superconducting coils. It is capable of detecting gravity variations as small as 10⁻¹¹ ms⁻². Because early production SG's lost helium at a steady rate, a large capacity dewar was required for reasonable periods of uninterrupted operation. In the late 1990's, Sumitomo Heavy Industries (SHI) developed a compact refrigeration system able to achieve liquid helium temperatures near 4K. It eliminates helium loss and allows a much smaller dewar to provide long intervals of continuous operation. These technical advances led us to develop an SG configured as a transportable field instrument. The goals were: 1) to package the entire SG system in two containers; 2) to test transport feasibility while the sensor remained in a superconducting levitated state; 3) to verify operability in field conditions; and 4) to determine the value of a transportable SG in groundwater and aquifer studies. We integrated the SG with a full weather station (measuring barometric pressure, rainfall, soil moisture etc.) and a geodetic GPS receiver (measuring vertical movement and atmospheric water vapor). All components were contained within enclosures constructed from angle and sheet aluminum. Each has dimensions ~1.5 x 0.8 x 1 m, total mass ~250 kg (including equipment) and can be transported easily by a medium truck while the sensor remained in a superconducting levitated state. Temporal gravity variations measured by the SG include solid Earth tides, pole-tide, atmospheric pressure effect, ocean loading effect, and terrestrial water storage variations. Most of these can be well modeled, except the last term. We developed a standard procedure for SG data processing. The first field deployment of the SG system was for the study of the Edwards aquifer, a Karst aquifer system that provides water resources in Central Texas, and was operated by a monitoring well equipped with transducer to measure water level changes. The residual gravity changes measured by the SG were only sensitive to the water storage changes underground. With well level measurements, it can be used to estimate aquifer's specific yield.Geological Science

Behavioral and Brain Measures of Morphological Processing in Children With and Without Familial Risk for Dyslexia From Pre-school to First Grade

School-age reading skills are associated with and predicted by preschool-age cognitive risk factors for dyslexia, such as deficits in phonological awareness, rapid automatized naming, letter knowledge, and verbal short-term memory. In addition, evidence exists that problems in morphological information processing could be considered a risk factor for dyslexia. In the present study, 27 children at pre-school age and the same 27 children at first grade age performed a morphological awareness task while their brain responses were measured with magnetoencephalography. Our aim was to examine how derivational morphology in Finnish language, and concomitant accuracy and reaction times are associated with first grade reading, in addition to the preschool age reading-related cognitive skills. The results replicated earlier findings; we found significant correlations between pre-school phonological skills and first-grade reading, pre-school rapid naming and first-grade reading, and pre-school verbal short-term memory and first-grade reading. The results also revealed a significant correlation between the pre-school children's reaction time for correctly derived words in the morphological task and the first-grade children's performance in rapid automatized naming for letters. No significant correlations were found between brain activation measures of morphological processing and first-grade reading.peerReviewe