Wolfgang Scharke

Task-Dependent Decoding of Speaker and Vowel Identity from Auditory Cortical Response Patterns

Selective attention to relevant sound properties is essential for everyday listening situations. It enables the formation of different perceptual representations of the same acoustic input and is at the basis of flexible and goal-dependent behavior. Here, we investigated the role of the human auditory cortex in forming behavior-dependent representations of sounds. We used single-trial fMRI and analyzed cortical responses collected while subjects listened to the same speech sounds (vowels /a/, /i/, and /u/) spoken by different speakers (boy, girl, male) and performed a delayed-match-to-sample task on either speech sound or speaker identity. Univariate analyses showed a task-specific activation increase in the right superior temporal gyrus/sulcus (STG/STS) during speaker categorization and in the right posterior temporal cortex during vowel categorization. Beyond regional differences in activation levels, multivariate classification of single trial responses demonstrated that the success with which single speakers and vowels can be decoded from auditory cortical activation patterns depends on task demands and subjects behavioral performance. Speaker/vowel classification relied on distinct but overlapping regions across the (right) mid-anterior STG/STS (speakers) and bilateral mid-posterior STG/STS (vowels), as well as the superior temporal plane including Heschls gyrus/sulcus. The task dependency of speaker/vowel classification demonstrates that the informative fMRI response patterns reflect the top-down enhancement of behaviorally relevant sound representations. Furthermore, our findings suggest that successful selection, processing, and retention of task-relevant sound properties relies on the joint encoding of information across early and higher-order regions of the auditory cortex.

Identifying brain systems for gaze orienting during reading: fMRI investigation of the Landolt paradigm

The Landolt reading paradigm was created in order to dissociate effects of eye movements and attention from lexical, syntactic, and sub-lexical processing. While previous eye-tracking and behavioral findings support the usefulness of the paradigm, it remains to be shown that the paradigm actually relies on the brain networks for occulomotor control and attention, but not on systems for lexical/syntactic/orthographic processing. Here, 20 healthy volunteers underwent fMRI scanning while reading sentences (with syntax) or unconnected lists of written stimuli (no syntax) consisting of words (with semantics) or pseudowords (no semantics). In an additional “Landolt reading” condition, all letters were replaced by closed circles, which should be scanned for targets (Landolts rings) in a reading-like fashion from left to right. A conjunction analysis of all five conditions revealed the visual scanning network which involved bilateral visual cortex, premotor cortex, and superior parietal cortex, but which did not include regions for semantics, syntax, or orthography. Contrasting the Landolt reading condition with all other regions revealed additional involvement of the right superior parietal cortex (areas 7A/7P/7PC) and postcentral gyrus (area 2) involved in deliberate gaze shifting. These neuroimaging findings demonstrate for the first time that the linguistic and orthographic brain network can be dissociated from a pure gaze-orienting network with the Landolt paradigm. Consequently, the Landolt paradigm may provide novel insights into the contributions of linguistic and non-linguistic factors on reading failure e.g., in developmental dyslexia.

Kindergarteners’ performance in a sound–symbol paradigm predicts early reading

The current study examined the role of serial processing of newly learned sound-symbol associations in early reading acquisition. A computer-based sound-symbol paradigm (SSP) was administered to 243 children during their last year of kindergarten (T1), and their reading performance was assessed 1 year later in first grade (T2). Results showed that performance on the SSP measured before formal reading instruction was associated with later reading development. At T1, early readers performed significantly better than nonreaders in learning correspondences between sounds and symbols as well as in applying those correspondences in a serial manner. At T2, SSP performance measured at T1 was positively associated with reading performance. Importantly, serial application of newly learned correspondences at T1 explained unique variance in first-grade reading performance in nonreaders over and above other verbal predictors, including phonological awareness, verbal short-term memory, and rapid automatized naming. Consequently, the SSP provides a promising way to study aspects of reading in preliterate children.

Sustained selective attention to competing amplitude-modulations in human auditory cortex

Auditory selective attention plays an essential role for identifying sounds of interest in a scene, but the neural underpinnings are still incompletely understood. Recent findings demonstrate that neural activity that is time-locked to a particular amplitude-modulation (AM) is enhanced in the auditory cortex when the modulated stream of sounds is selectively attended to under sensory competition with other streams. However, the target sounds used in the previous studies differed not only in their AM, but also in other sound features, such as carrier frequency or location. Thus, it remains uncertain whether the observed enhancements reflect AM-selective attention. The present study aims at dissociating the effect of AM frequency on response enhancement in auditory cortex by using an ongoing auditory stimulus that contains two competing targets differing exclusively in their AM frequency. Electroencephalography results showed a sustained response enhancement for auditory attention compared to visual attention, but not for AM-selective attention (attended AM frequency vs. ignored AM frequency). In contrast, the response to the ignored AM frequency was enhanced, although a brief trend toward response enhancement occurred during the initial 15 s. Together with the previous findings, these observations indicate that selective enhancement of attended AMs in auditory cortex is adaptive under sustained AM-selective attention. This finding has implications for our understanding of cortical mechanisms for feature-based attentional gain control.

Brain-to-brain synchrony in parent-child dyads and the relationship with emotion regulation revealed by fNIRS-based hyperscanning

Abstract Parent‐child synchrony, the coupling of behavioral and biological signals during social contact, may fine‐tune the childs brain circuitries associated with emotional bond formation and the childs development of emotion regulation. Here, we examined the neurobiological underpinnings of these processes by measuring parents and childs prefrontal neural activity concurrently with functional near‐infrared spectroscopy hyperscanning. Each child played both a cooperative and a competitive game with the parent, mostly the mother, as well as an adult stranger. During cooperation, parents and childs brain activities synchronized in the dorsolateral prefrontal and frontopolar cortex (FPC), which was predictive for their cooperative performance in subsequent trials. No significant brain‐to‐brain synchrony was observed in the conditions parent‐child competition, stranger‐child cooperation and stranger‐child competition. Furthermore, parent‐child compared to stranger‐child brain‐to‐brain synchrony during cooperation in the FPC mediated the association between the parents and the childs emotion regulation, as assessed by questionnaires. Thus, we conclude that brain‐to‐brain synchrony may represent an underlying neural mechanism of the emotional connection between parent and child, which is linked to the childs development of adaptive emotion regulation. Future studies may uncover whether brain‐to‐brain synchrony can serve as a neurobiological marker of the dyads socio‐emotional interaction, which is sensitive to risk conditions, and can be modified by interventions. HighlightsBrain activities of parent and child synchronize during cooperation.No significant brain‐to‐brain synchrony for stranger‐child dyads.Parent‐child brain‐to‐brain synchrony predicts cooperative performance.Parent‐child brain‐to‐brain synchrony is linked to childs emotion regulation.

Developmental refinement of cortical systems for speech and voice processing

Development typically leads to optimized and adaptive neural mechanisms for the processing of voice and speech. In this fMRI study we investigated how this adaptive processing reaches its mature efficiency by examining the effects of task, age and phonological skills on cortical responses to voice and speech in children (8-9years), adolescents (14-15years) and adults. Participants listened to vowels (/a/, /i/, /u/) spoken by different speakers (boy, girl, man) and performed delayed-match-to-sample tasks on vowel and speaker identity. Across age groups, similar behavioral accuracy and comparable sound evoked auditory cortical fMRI responses were observed. Analysis of task-related modulations indicated a developmental enhancement of responses in the (right) superior temporal cortex during the processing of speaker information. This effect was most evident through an analysis based on individually determined voice sensitive regions. Analysis of age effects indicated that the recruitment of regions in the temporal-parietal cortex and posterior cingulate/cingulate gyrus decreased with development. Beyond age-related changes, the strength of speech-evoked activity in left posterior and right middle superior temporal regions significantly scaled with individual differences in phonological skills. Together, these findings suggest a prolonged development of the cortical functional network for speech and voice processing. This development includes a progressive refinement of the neural mechanisms for the selection and analysis of auditory information relevant to the ongoing behavioral task.

Nonword reading and Stroop interference: What differentiates attention-deficit/hyperactivity disorder and reading disability?

Background: Attention deficits and impaired reading performance co-occur more often than expected by chance; however, the underlying mechanism of this association still remains rather unexplored. Method: In two consecutive studies, children aged 8 to 12 years with attention-deficit/hyperactivity disorder (ADHD) and children with reading disability (RD) were examined using a 2 (ADHD versus no ADHD) × 2 (RD versus no RD) factorial design. To further delineate deficient interference control from reading processes, we used a newly developed self-paced word/nonword reading task (Experiment 1, n = 68) and a modified computerized Stroop paradigm, including an orthographic phonological neighbor (OPN) condition (Experiment 2, n = 84). Results: RD (compared to non-RD groups) was associated with impairments in both word and nonword reading, while children with ADHD also showed impaired nonword reading. In the Stroop task, RD, but not ADHD, had a significant impact on task performance. Interestingly, a significant interaction between ADHD, RD, and task condition emerged, which was due to particularly slower reaction times to nonwords in children with RD only, while task performance in children with comorbid ADHD and RD resembled that of ADHD only. Conclusions: Thus, our results demonstrate that impairments in nonword reading were not specific to RD but were also present in children with ADHD. In addition, RD and not ADHD was characterized by poor interference control in the Stroop task. These findings question whether unique cognitive deficits are specific to either ADHD or RD.

Performance in sound-symbol learning predicts reading performance three years later

To master the task of reading, children need to acquire a coding system representing speech as a sequence of visual symbols. Recent research suggested that performance in the processing of artificial script that relies on the association of sound and symbol may be associated with reading skill. The current longitudinal study examined the predictive value of a preschool sound-symbol paradigm (SSP) of reading performance 3 years later. The Morse-like SSP, IQ, and letter knowledge (LK) was assessed in young preschool children. Reading outcome measures were examined 3 years later. Word reading, pseudoword reading, and reading comprehension were predicted with age, IQ, LK, and SSP. The results showed that SSP substantially predicted reading fluency and reading comprehension 3 years later. For reading fluency measures, the influence of further predictor variables was not significant and SSP served as a sole predictor. Reading comprehension was best explained by SSP and age. The amount of variance SSP explained in reading 3 years later was remarkably high, with an explained variance between 63 and 82%, depending on the outcome reading variable. SSP turned out to be a substantial predictor of later reading performance in a language with statistically reliable spelling-to-sound relations. As LK is highly dependent on educational support, we assume that children in our socioeconomically diverse sample did not have much opportunity to acquire LK in their home environment. In contrast, the SSP challenges students to acquire new spelling-to-sound relations, simulating a core aspect of natural reading acquisition. Future work will test this paradigm in less transparent languages like English and explore its potential as a future standard assessment in the study of early reading development.

Effects of Early-Life Adversity on Hippocampal Structures and Associated HPA Axis Functions

Early-life adversity (ELA) is one of the major risk factors for serious mental and physical health risks later in life. ELA has been associated with dysfunctional neurodevelopment, especially in brain structures such as the hippocampus, and with dysfunction of the stress system, including the hypothalamic-pituitary-adrenal (HPA) axis. Children who have experienced ELA are also more likely to suffer from mental health disorders such as depression later in life. The exact interplay of aberrant neurodevelopment and HPA axis dysfunction as risks for psychopathology is not yet clear. We investigated volume differences in the bilateral hippocampus and in stress-sensitive hippocampal subfields, behavior problems, and diurnal cortisol activity in 24 children who had experienced documented ELA (including out-of-home placement) in a circumscribed duration of adversity only in their first 3 years of life in comparison to data on 25 control children raised by their biological parents. Hippocampal volumes and stress-sensitive hippocampal subfields (Cornu ammonis [CA]1, CA3, and the granule-cell layer of the dentate gyrus [GCL-DG]) were significantly smaller in children who had experienced ELA, taking psychiatric diagnoses and dimensional psychopathological symptoms into account. ELA moderated the relationship between left hippocampal volume and cortisol: in the control group, hippocampal volumes were not related to diurnal cortisol, while in ELA children, a positive linear relationship between left hippocampal volume and diurnal cortisol was present. Our findings show that ELA is associated with altered development of the hippocampus, and an altered relationship between hippocampal volume and HPA axis activity in youth in care, even after they have lived in stable and caring foster family environments for years. Altered hippocampal development after ELA could thus be associated with a risk phenotype for the development of psychiatric disorders later in life.

Cognitive development in children of adolescent mothers: The impact of socioeconomic risk and maternal sensitivity

BACKGROUND Adolescent motherhood is accompanied by a constellation of risk factors that translate into developmental risk for the off-spring. Socioeconomic risk that is associated with adolescent motherhood as well as maternal interactive behaviors may contribute to the impact of adolescent motherhood on childrens developmental outcome. OBJECTIVE Therefore, the aim of the current study was to investigate differences in childrens cognitive development between children of adolescent and adult mothers in their first two years of life and to examine whether socioeconomic risk (e.g. such as educational and financial problems) and/or maternal sensitivity mediate developmental differences between children of adolescent and adult mothers. METHODS Adolescent mothers (<21 years; N = 64) and adult mothers (>25 years; N = 34) and their infants were included in the current study. Child cognitive development and maternal sensitivity were assessed at three different time points (T1: mean child age 5.26 months; T2: mean child age 14.69 months; T3: mean child age 21.16 months). RESULTS Children of adult mothers showed better cognitive performance at T3 compared to children of adolescent mothers but not at T1 and T2. A multiple mediation model including socioeconomic risk and maternal sensitivity as serial mediators demonstrated that the effect of adolescent motherhood on cognitive development was mediated in a causal effect chain with socioeconomic risk negatively affecting maternal sensitivity and maternal sensitivity affecting childrens cognitive development. DISCUSSION The present findings demonstrate that maternal interactive behaviors are not only a simple predictor of cognitive development but may also act as a mediator of the association between more distal variables such as socioeconomic risk and cognitive development in adolescent mothers. This supports the need to promote prevention and intervention programs for adolescent mothers during the early postpartum period to reduce socioeconomic problems and enhance maternal interactive behaviors.