Disruption of the neural response to rapid acoustic stimuli in dyslexia: evidence from functional MRI

Abnormal brain activation during speech perception and production in children and adults with reading difficulty

Reading difficulty (RD) is associated with phonological deficits; however, it remains unknown whether the phonological deficits are different in children and adults with RD as reflected in foreign speech perception and production. In the current study, using functional Near-infrared spectroscopy (fNIRS), we found less difference between Chinese adults and Chinese children in the RD groups than the control groups in the activation of the right inferior frontal gyrus (IFG) and the dorsolateral prefrontal cortex (DLPFC) during Spanish speech perception, suggesting slowed development in these regions associated with RD. Furthermore, using multivariate pattern analysis (MVPA), we found that activation patterns in the left middle temporal gyrus (MTG), premotor, supplementary motor area (SMA), and IFG could serve as reliable markers of RD. We provide both behavioral and neurological evidence for impaired speech perception and production in RD readers which can serve as markers of RD.

Computer-vision analysis of craniofacial dysmorphology in 22q11.2 deletion syndrome and psychosis spectrum disorders

BACKGROUND

Minor physical anomalies (MPAs) are congenital morphological abnormalities linked to disruptions of fetal development. MPAs are common in 22q11.2 deletion syndrome (22q11DS) and psychosis spectrum disorders (PS) and likely represent a disruption of early embryologic development that may help identify overlapping mechanisms linked to psychosis in these disorders.

METHODS

Here, 2D digital photographs were collected from 22q11DS (n = 150), PS (n = 55), and typically developing (TD; n = 93) individuals. Photographs were analyzed using two computer-vision techniques: (1) DeepGestalt algorithm (Face2Gene (F2G)) technology to identify the presence of genetically mediated facial disorders, and (2) Emotrics-a semi-automated machine learning technique that localizes and measures facial features.

RESULTS

F2G reliably identified patients with 22q11DS; faces of PS patients were matched to several genetic conditions including FragileX and 22q11DS. PCA-derived factor loadings of all F2G scores indicated unique and overlapping facial patterns that were related to both 22q11DS and PS. Regional facial measurements of the eyes and nose were smaller in 22q11DS as compared to TD, while PS showed intermediate measurements.

CONCLUSIONS

The extent to which craniofacial dysmorphology 22q11DS and PS overlapping and evident before the impairment or distress of sub-psychotic symptoms may allow us to identify at-risk youths more reliably and at an earlier stage of development.

Examination of common and unique brain regions for atypical reading and math: a meta-analysis

The purpose of this study is to identify consistencies across functional neuroimaging studies regarding common and unique brain regions/networks for individuals with reading difficulties (RD) and math difficulties (MD) compared to typically developing (TD) individuals. A systematic search of the literature, utilizing multiple databases, yielded 116 functional magnetic resonance imaging and positron emission tomography studies that met the criteria. Coordinates that directly compared TD with either RD or MD were entered into GingerALE (Brainmap.org). An activation likelihood estimate (ALE) meta-analysis was conducted to examine common and unique brain regions for RD and MD. Overall, more studies examined RD (n = 96) than MD (n = 20). Across studies, overactivation for reading and math occurred in the right insula and inferior frontal gyrus for atypically developing (AD) > TD comparisons, albeit in slightly different areas of these regions; however, inherent threshold variability across imaging studies could diminish overlying regions. For TD > AD comparisons, there were no similar or overlapping brain regions. Results indicate there were domain-specific differences for RD and MD; however, there were some similarities in the ancillary recruitment of executive functioning skills. Theoretical and practical implications for researchers and educators are discussed.

Temporal processing deficit in children and adolescents with autism spectrum disorder: An online assessment

Objective

The sensory deficit has been considered as one of the core features in children and adolescents with autism spectrum disorder (ASD). The present study aimed to examine the temporal processing of simple and more complex auditory inputs in ASD children and adolescents with an online assessment that can be conducted remotely.

Methods

One hundred fifty-eight children and adolescents aged 5-17 years participated in this study, including 79 ASD participants and 79 typically developing (TD) participants. The online assessment consisted of two temporal-order judgment tasks that required repeating the sequence of two pure tones or consonant-vowel (CV) syllabic pairs at varying interstimulus intervals (ISIs).

Results

Significantly lower accuracy rates were found in ASD than TD participants in the pure tone and the CV conditions with both short and long ISI. In addition, ASD participants (M  =  245.97 ms) showed a significantly higher passing threshold than TD participants (M  =  178.84 ms) in the CV task. Receiver operating characteristic analysis found that the age × ISI passing threshold composite yielded a sensitivity of 74.7% and a specificity of 50.6% at the cutoff point of -0.307 in differentiating ASD participants from TD participants.

Conclusion

In sum, children and adolescents with ASD showed impaired temporal processing of both simple and more complex auditory stimuli, and the online assessment seems to be sensitive in differentiating individuals with ASD from those with TD.

Music-Based and Auditory-Based Interventions for Reading Difficulties: A Literature Review

Remediation of reading difficulties through music and auditory-based interventions in children with impairments in reading (such as developmental dyslexia) has been suggested in light of the putative neural and cognitive overlaps between the music and language domains. Several studies had explored the effect of music training on reading development, showing mixed results. However, to date, the meta-analyses on this topic did not differentiate the studies on typical children from those on children with reading difficulties. To draw a clear picture of the remedial effects of music-based and auditory-based interventions, the present review of the literature included studies on struggling readers only. Eighteen studies have been categorized according to the type of the main training activity – either specific auditory training or more broad music training – and the combination with reading exercises. The reviewed studies showed that musical and auditory interventions yielded a positive, but not consistent, effect on reading. Nevertheless, significantly larger improvements of phonological abilities, relative to the control conditions, were overall reported. These findings support the hypothesis of a transfer effect of musical and auditory training on phonological and literacy skills in children with reading difficulties.

Convergent and divergent brain structural and functional abnormalities associated with developmental dyslexia

Brain abnormalities in the reading network have been repeatedly reported in individuals with developmental dyslexia (DD); however, it is still not totally understood where the structural and functional abnormalities are consistent/inconsistent across languages. In the current multimodal meta-analysis, we found convergent structural and functional alterations in the left superior temporal gyrus across languages, suggesting a neural signature of DD. We found greater reduction in grey matter volume and brain activation in the left inferior frontal gyrus in morpho-syllabic languages (e.g. Chinese) than in alphabetic languages, and greater reduction in brain activation in the left middle temporal gyrus and fusiform gyrus in alphabetic languages than in morpho-syllabic languages. These language differences are explained as consequences of being DD while learning a specific language. In addition, we also found brain regions that showed increased grey matter volume and brain activation, presumably suggesting compensations and brain regions that showed inconsistent alterations in brain structure and function. Our study provides important insights about the etiology of DD from a cross-linguistic perspective with considerations of consistency/inconsistency between structural and functional alterations.

Hemispheric and Sex Differences in Mustached Bat Primary Auditory Cortex Revealed by Neural Responses to Slow Frequency Modulations

The mustached bat (Pteronotus parnellii) is a mammalian model of cortical hemispheric asymmetry. In this species, complex social vocalizations are processed preferentially in the left Doppler-shifted constant frequency (DSCF) subregion of primary auditory cortex. Like hemispheric specializations for speech and music, this bat brain asymmetry differs between sexes (i.e., males>females) and is linked to spectrotemporal processing based on selectivities to frequency modulations (FMs) with rapid rates (>0.5 kHz/ms). Analyzing responses to the long-duration (>10 ms), slow-rate (<0.5 kHz/ms) FMs to which most DSCF neurons respond may reveal additional neural substrates underlying this asymmetry. Here, we bilaterally recorded responses from 176 DSCF neurons in male and female bats that were elicited by upward and downward FMs fixed at 0.04 kHz/ms and presented at 0-90 dB SPL. In females, we found inter-hemispheric latency differences consistent with applying different temporal windows to precisely integrate spectrotemporal information. In males, we found a substrate for asymmetry less related to spectrotemporal processing than to acoustic energy (i.e., amplitude). These results suggest that in the DSCF area, (1) hemispheric differences in spectrotemporal processing manifest differently between sexes, and (2) cortical asymmetry for social communication is driven by spectrotemporal processing differences and neural selectivities for amplitude.

Investigating Issues and Needs of Dyslexic Students at University: Proof of Concept of an Artificial Intelligence and Virtual Reality-Based Supporting Platform and Preliminary Results

Specific learning disorders affect a significant portion of the population. A total of 80% of its instances are dyslexia, which causes significant difficulties in learning skills related to reading, memorizing and the exposition of concepts. Whereas great efforts have been made to diagnose dyslexia and to mitigate its effects at primary and secondary school, little has been done at the university level. This has resulted in a sensibly high rate of abandonment or even of failures to enroll. The VRAIlexia project was created to face this problem by creating and popularizing an innovative method of teaching that is inclusive for dyslexic students. The core of the project is BESPECIAL, a software platform based on artificial intelligence and virtual reality that is capable of understanding the main issues experienced by dyslexic students and to provide them with ad hoc digital support methodologies in order to ease the difficulties they face in their academic studies. The aim of this paper is to present the conceptual design of BESPECIAL, highlighting the role of each module that composes it and the potential of the whole platform to fulfil the aims of VRAIlexia. Preliminary results obtained from a sample of about 700 dyslexic students are also reported, which clearly show the main issues and needs that dyslexic students experience and these will be used as guidelines for the final implementation of BESPECIAL.

Study of functional magnetic resonance imaging (fMRI) in children and adolescents with specific learning disorder (dyslexia)

BACKGROUND

Dyslexia is a type of specific learning disability (SLD) which has neurobiological origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. The impaired reading in dyslexia is associated with inability to process the sensory input that enters the nervous system. Functional magnetic resonance imaging (fMRI) has emerged as a potential source in understanding the neurobiology and to identify the brain basis of sensory stimuli processed in dyslexic patients.

METHODOLOGY

The present study was conducted to assess the difference in neural changes using fMRI in children and adolescents with SLD compared with normal children and also the correlation of clinical parameters with BOLD - fMRI changes. Sixteen children and adolescents diagnosed as dyslexia were assessed with All India Institute of Medical Sciences (AIIMS) SLD Battery, Mini-International Neuropsychiatric Interview for Children and Adolescents (MINI KID) and Aggregated Neurobehavioral Student Health and Educational Review (ANSER) system and compared with 15 controls matched with age and sex. Participants of both groups were asked to perform 3 tasks during the fMRI acquisition (phonological, picture-naming and semantic tasks).

RESULT

As compared to control group, the participants with dyslexia show phonological decoding problem. During picture task, the participants with dyslexia use more areas of brain involve in recalling the memory events while during semantic tasks processing the occipito-temporal (fusiform) gyrus was less activated when in contrast to control.

CONCLUSION

This study shows that participants with dyslexia fail to use normal brain regions specialized in language processing, but rather use different areas.

Music-related abilities among readers with dyslexia

Research suggests that a central difficulty in dyslexia may be impaired rapid temporal processing. Good temporal processing is also needed for musical perception, which relies on the ability to detect rapid changes. Our study is the first to measure the perception of adults with and without dyslexia on all three dimensions of music (rhythm, pitch, and spectrum), as well as their capacity for auditory imagery and detection of slow changes, while controlling for working memory. Participants were undergraduate students, aged 20-35 years: 26 readers with dyslexia and 30 typical readers. Participants completed a battery of tests measuring aptitude for recognizing the similarity/difference in tone pitch or rhythm, spectral resolution, vividness/control of auditory imagination, the ability to detect slow changes in auditory stimuli, and working memory. As expected, readers with dyslexia showed poorer performance in pitch and rhythm than controls, but outperformed them in spectral perception. The data for each test was analyzed separately while controlling for the letter-number sequencing score. No differences between groups were found in slow-change detection or auditory imagery. Our results demonstrated that rapid temporal processing appears to be the main difficulty of readers with dyslexia, who demonstrated poorer performance when stimuli were presented quickly rather than slowly and better performance on a task when no temporal component was involved. These findings underscore the need for further study of temporal processing in readers with dyslexia. Remediation of temporal processing deficits may unmask the preserved or even superior abilities of people with dyslexia, leading to enhanced ability in all areas that utilize the temporal component.

Analysis of the components of Frequency-Following Response in phonological disorders

INTRODUCTION

When identifying the auditory performance of children with phonological disorders, researchers assume that this population has normal peripheral hearing. However, responses at more central levels might be atypical.

OBJECTIVE

To investigate the effect of phonological disorders on Frequency-Following Responses (FFRs) in the time domain.

METHODS

Participants were 60 subjects, aged 5 to 8:11 years, divided into two groups: a control group, composed of 30 subjects with normal language skills; and a study group composed of 30 subjects diagnosed with Phonological Disorder (PD). All subjects were tested for Frequency-Following Responses.

RESULTS

In the group of children with PD there was an increase in the latency of all FFR components, with a significant statistical difference for components V (p = 0.015); A (<0.001); C (0.022); F (<0.001); and O (0.001). There was also a reduction in the Slope measure in the group with PD (p = 0.004).

CONCLUSION

The FFR responses are altered in children with PD. This suggests that children with PD present a disorganization in the neural coding of complex sounds. This could compromise specially the development of linguistic/phonological abilities, which can reflect in daily communication.

Reading deficits in schizophrenia and their relationship to developmental dyslexia: A review

Although schizophrenia and developmental dyslexia are considered distinct disorders in terms of clinical presentation and functional outcome, they both involve disruption in the processes that support skilled reading, including language, auditory perception, visual perception, oculomotor control, and executive function. Further, recent work has proposed a common neurodevelopmental basis for the two disorders, as suggested by genetic and pathophysiological overlap. Thus, these lines of research suggest that reading may be similarly impacted in schizophrenia and dyslexia. In this review, we survey research on reading abilities in individuals with schizophrenia, and review the potential mechanisms underlying reading deficits in schizophrenia that may be shared with those implicated in dyslexia. Elucidating the relationship between reading impairment in schizophrenia and dyslexia could allow for a better understanding of the pathophysiological underpinnings of schizophrenia, and could facilitate remediation of cognitive deficits that impact day-to-day functioning.

Cortical responses to tone and phoneme mismatch as a predictor of dyslexia? A systematic review

Evidence from event-related-potential (ERP) studies has repeatedly shown differences in the perception and processing of auditory stimuli in children with dyslexia compared to control children. The mismatch negativity (MMN) - an ERP component reflecting passive auditory change detection ability - has been found to be reduced, not only in children with a diagnosis of dyslexia, but also in infants and preschool children at risk of developing dyslexia. However, the results are controversial due to the different methods, age of the children and stimuli used. The aim of the present review is to summarize and evaluate the MMN research about at-risk children in order to identify risk factors that discriminate between children with and without dyslexia risk and to analyze if the MMR (the abbreviation refers to positive and negative mismatch responses) correlates with later reading and spelling ability. A literature search yielded 17 studies reporting MMR to speech or non-speech stimuli in children at risk of dyslexia. The results of the studies were inconsistent. Studies measuring speech MMR often found attenuated amplitudes in the at-risk group, but mainly in very young children. The results for older children (6-7years) and for non-speech stimuli are more heterogeneous. A moderate positive correlation of MMR amplitude size with later reading and spelling abilities was consistently found. Overall, the findings of this review indicate that the MMR can be a valuable part of early dyslexia identification, which can enable efficient support and intervention for a child before the first problems appear.

Knockout Mice for Dyslexia Susceptibility Gene Homologs KIAA0319 and KIAA0319L have Unaffected Neuronal Migration but Display Abnormal Auditory Processing

Developmental dyslexia is a neurodevelopmental disorder that affects reading ability caused by genetic and non-genetic factors. Amongst the susceptibility genes identified to date, KIAA0319 is a prime candidate. RNA-interference experiments in rats suggested its involvement in cortical migration but we could not confirm these findings in Kiaa0319-mutant mice. Given its homologous gene Kiaa0319L (AU040320) has also been proposed to play a role in neuronal migration, we interrogated whether absence of AU040320 alone or together with KIAA0319 affects migration in the developing brain. Analyses of AU040320 and double Kiaa0319;AU040320 knockouts (dKO) revealed no evidence for impaired cortical lamination, neuronal migration, neurogenesis or other anatomical abnormalities. However, dKO mice displayed an auditory deficit in a behavioral gap-in-noise detection task. In addition, recordings of click-evoked auditory brainstem responses revealed suprathreshold deficits in wave III amplitude in AU040320-KO mice, and more general deficits in dKOs. These findings suggest that absence of AU040320 disrupts firing and/or synchrony of activity in the auditory brainstem, while loss of both proteins might affect both peripheral and central auditory function. Overall, these results stand against the proposed role of KIAA0319 and AU040320 in neuronal migration and outline their relationship with deficits in the auditory system.

Specific effects of working memory training on the reading skills of Chinese children with developmental dyslexia

Most research on working memory (WM) training for children with developmental dyslexia (DD) has focused on western alphabetical languages. Moreover, most of these studies used a combination of training tasks targeting a variety of WM components, making it difficult to determine whether WM training generates a general improvement in overall reading, or improves specific cognitive skills corresponding to the WM components that are targeted in training. We tested the general and specific effects of WM training on the reading skills of 45 Chinese children with DD, grades 3 to 5. In Experiment 1, the experimental group received a program targeting the verbal WM component; in Experiment 2, the experimental group was trained with a program targeting visuospatial WM. In both experiments the control group played a placebo video game. In Experiment 1, the experimental group outperformed the control group on the visual rhyming task, which is highly correlated with verbal WM. In Experiment 2, the experimental group outperformed the control group on the orthographic awareness test, which is highly correlated with visuospatial WM. Furthermore, in both Experiment 1 and Experiment 2, the experimental groups outperformed the control groups on the fast word naming test, which is highly related to both visuospatial WM and verbal WM. Results indicated that WM training improved specific reading-related cognitive skills that are highly correlated with the specific WM components that were the target of training.

Knockdown of Dyslexia-Gene Dcdc2 Interferes with Speech Sound Discrimination in Continuous Streams

Dyslexia is the most common developmental language disorder and is marked by deficits in reading and phonological awareness. One theory of dyslexia suggests that the phonological awareness deficit is due to abnormal auditory processing of speech sounds. Variants in DCDC2 and several other neural migration genes are associated with dyslexia and may contribute to auditory processing deficits. In the current study, we tested the hypothesis that RNAi suppression of Dcdc2 in rats causes abnormal cortical responses to sound and impaired speech sound discrimination. In the current study, rats were subjected in utero to RNA interference targeting of the gene Dcdc2 or a scrambled sequence. Primary auditory cortex (A1) responses were acquired from 11 rats (5 with Dcdc2 RNAi; DC-) before any behavioral training. A separate group of 8 rats (3 DC-) were trained on a variety of speech sound discrimination tasks, and auditory cortex responses were acquired following training. Dcdc2 RNAi nearly eliminated the ability of rats to identify specific speech sounds from a continuous train of speech sounds but did not impair performance during discrimination of isolated speech sounds. The neural responses to speech sounds in A1 were not degraded as a function of presentation rate before training. These results suggest that A1 is not directly involved in the impaired speech discrimination caused by Dcdc2 RNAi. This result contrasts earlier results using Kiaa0319 RNAi and suggests that different dyslexia genes may cause different deficits in the speech processing circuitry, which may explain differential responses to therapy.

SIGNIFICANCE STATEMENT

Although dyslexia is diagnosed through reading difficulty, there is a great deal of variation in the phenotypes of these individuals. The underlying neural and genetic mechanisms causing these differences are still widely debated. In the current study, we demonstrate that suppression of a candidate-dyslexia gene causes deficits on tasks of rapid stimulus processing. These animals also exhibited abnormal neural plasticity after training, which may be a mechanism for why some children with dyslexia do not respond to intervention. These results are in stark contrast to our previous work with a different candidate gene, which caused a different set of deficits. Our results shed some light on possible neural and genetic mechanisms causing heterogeneity in the dyslexic population.

Dyslexics' faster decay of implicit memory for sounds and words is manifested in their shorter neural adaptation

Dyslexia is a prevalent reading disability whose underlying mechanisms are still disputed. We studied the neural mechanisms underlying dyslexia using a simple frequency-discrimination task. Though participants were asked to compare the two tones in each trial, implicit memory of previous trials affected their responses. We hypothesized that implicit memory decays faster among dyslexics. We tested this by increasing the temporal intervals between consecutive trials, and by measuring the behavioral impact and ERP responses from the auditory cortex. Dyslexics showed a faster decay of implicit memory effects on both measures, with similar time constants. Finally, faster decay of implicit memory also characterized the impact of sound regularities in benefitting dyslexics' oral reading rate. Their benefit decreased faster as a function of the time interval from the previous reading of the same non-word. We propose that dyslexics’ shorter neural adaptation paradoxically accounts for their longer reading times, since it reduces their temporal window of integration of past stimuli, resulting in noisier and less reliable predictions for both simple and complex stimuli. Less reliable predictions limit their acquisition of reading expertise.

DOI:http://dx.doi.org/10.7554/eLife.20557.001

The term “dyslexia” comes from the Greek for “difficulty with words”. People with dyslexia struggle with reading and spelling: they may mix up letters within words and tend to read and write more slowly than others. However, not every symptom of dyslexia is related to literacy. Affected individuals also differ from good readers on simple perceptual tasks, such as distinguishing between tones of different frequencies.

In a series of trials involving discrimination between pairs of tones, a person’s performance on each trial will be influenced by the tones presented on previous trials. Both good readers and individuals with dyslexia automatically form a subconscious memory of the tones they hear, and use this memory to guide their performance on subsequent trials. However, people with dyslexia benefit less from this effect than good readers.

Jaffe-Dax et al. have now identified the mechanism that underlies this phenomenon, revealing new insights into how dyslexia influences brain activity. By varying the interval between successive pairs of tones, the experiments showed that the memory of previous tones decays faster in people with dyslexia than in good readers. A similar effect occurs when the stimuli are nonsense words. Both good and poor readers manage to read nonsense words more quickly on their second attempt. However, people with dyslexia benefit less from the previous exposure when the gap between repetitions is longer than a couple of seconds.

Further studies are needed to determine whether and how the faster decay of memory traces for words is related to impaired reading ability in people with dyslexia. One possibility is that the faster decay of memory traces makes it more difficult to predict future stimuli, which may impair reading. An imaging study is underway to investigate where in the brain this rapid decay of memory traces occurs.

DOI:http://dx.doi.org/10.7554/eLife.20557.002

Effect of hearing aids use on speech stimulus decoding through speech-evoked ABR

INTRODUCTION

The electrophysiological responses obtained with the complex auditory brainstem response (cABR) provide objective measures of subcortical processing of speech and other complex stimuli. The cABR has also been used to verify the plasticity in the auditory pathway in the subcortical regions.

OBJECTIVE

To compare the results of cABR obtained in children using hearing aids before and after 9 months of adaptation, as well as to compare the results of these children with those obtained in children with normal hearing.

METHODS

Fourteen children with normal hearing (Control Group - CG) and 18 children with mild to moderate bilateral sensorineural hearing loss (Study Group - SG), aged 7-12 years, were evaluated. The children were submitted to pure tone and vocal audiometry, acoustic immittance measurements and ABR with speech stimulus, being submitted to the evaluations at three different moments: initial evaluation (M0), 3 months after the initial evaluation (M3) and 9 months after the evaluation (M9); at M0, the children assessed in the study group did not use hearing aids yet.

RESULTS

When comparing the CG and the SG, it was observed that the SG had a lower median for the V-A amplitude at M0 and M3, lower median for the latency of the component V at M9 and a higher median for the latency of component O at M3 and M9. A reduction in the latency of component A at M9 was observed in the SG.

CONCLUSION

Children with mild to moderate hearing loss showed speech stimulus processing deficits and the main impairment is related to the decoding of the transient portion of this stimulus spectrum. It was demonstrated that the use of hearing aids promoted neuronal plasticity of the Central Auditory Nervous System after an extended time of sensory stimulation.

Neural Mechanisms of Language-Based Learning Impairments: Insights from Human Populations and Animal Models

The acquisition of speech perception and consequent expression of language represent fundamental aspects of human functioning. Yet roughly 7% to 8% of children who are otherwise healthy and of normal intelligence exhibit unexplained delays and impairments in acquiring these skills. Ongoing research has revealed several key features of language disability that may pro-vide more direct insight into underlying anomalous neural functioning. For example, evidence supports a strong association between basic defects in processing rapidly changing acoustic information and emergent disruptions in speech perception, as well as cascading effects on other forms of language development (including reading). Considerable neurobiological research has thus focused on developmental factors that might deleteriously influence rapid sensory processing. Additional research focuses on mechanisms of neural plasticity, including how such brains might be “retrained” for improved processing of language. These and related findings from human clinical studies, electrophysiological studies, neuroimaging studies, and animal models are reviewed.

Conjugating time and frequency: hemispheric specialization, acoustic uncertainty, and the mustached bat

A prominent hypothesis of hemispheric specialization for human speech and music states that the left and right auditory cortices (ACs) are respectively specialized for precise calculation of two canonically-conjugate variables: time and frequency. This spectral-temporal asymmetry does not account for sex, brain-volume, or handedness, and is in opposition to closed-system hypotheses that restrict this asymmetry to humans. Mustached bats have smaller brains, but greater ethological pressures to develop such a spectral-temporal asymmetry, than humans. Using the Heisenberg-Gabor Limit (i.e., the mathematical basis of the spectral-temporal asymmetry) to frame mustached bat literature, we show that recent findings in bat AC (1) support the notion that hemispheric specialization for speech and music is based on hemispheric differences in temporal and spectral resolution, (2) discredit closed-system, handedness, and brain-volume theories, (3) underscore the importance of sex differences, and (4) provide new avenues for phonological research.

A compensatory role for declarative memory in neurodevelopmental disorders

Most research on neurodevelopmental disorders has focused on their abnormalities. However, what remains intact may also be important. Increasing evidence suggests that declarative memory, a critical learning and memory system in the brain, remains largely functional in a number of neurodevelopmental disorders. Because declarative memory remains functional in these disorders, and because it can learn and retain numerous types of information, functions, and tasks, this system should be able to play compensatory roles for multiple types of impairments across the disorders. Here, we examine this hypothesis for specific language impairment, dyslexia, autism spectrum disorder, Tourette syndrome, and obsessive-compulsive disorder. We lay out specific predictions for the hypothesis and review existing behavioral, electrophysiological, and neuroimaging evidence. Overall, the evidence suggests that declarative memory indeed plays compensatory roles for a range of impairments across all five disorders. Finally, we discuss diagnostic, therapeutic and other implications.

Classifying acoustic signals into phoneme categories: average and dyslexic readers make use of complex dynamical patterns and multifractal scaling properties of the speech signal

Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis) to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The ‘classical’ features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions). Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum) enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired) speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the ‘classical’ aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception performance between average and dyslexic readers represent a scaled continuum rather than being caused by a specific deficient component.

Reading the dyslexic brain: multiple dysfunctional routes revealed by a new meta-analysis of PET and fMRI activation studies

Developmental dyslexia has been the focus of much functional anatomical research. The main trust of this work is that typical developmental dyslexics have a dysfunction of the phonological and orthography to phonology conversion systems, in which the left occipito-temporal cortex has a crucial role. It remains to be seen whether there is a systematic co-occurrence of dysfunctional patterns of different functional systems perhaps converging on the same brain regions associated with the reading deficit. Such evidence would be relevant for theories like, for example, the magnocellular/attentional or the motor/cerebellar ones, which postulate a more basic and anatomically distributed disorder in dyslexia. We addressed this issue with a meta-analysis of all the imaging literature published until September 2013 using a combination of hierarchical clustering and activation likelihood estimation methods. The clustering analysis on 2360 peaks identified 193 clusters, 92 of which proved spatially significant. Following binomial tests on the clusters, we found left hemispheric network specific for normal controls (i.e., of reduced involvement in dyslexics) including the left inferior frontal, premotor, supramarginal cortices and the left infero-temporal and fusiform regions: these were preferentially associated with reading and the visual-to-phonology processes. There was also a more dorsal left fronto-parietal network: these clusters included peaks from tasks involving phonological manipulation, but also motoric or visuo-spatial perception/attention. No cluster was identified in area V5 for no task, nor cerebellar clusters showed a reduced association with dyslexics. We conclude that the examined literature demonstrates a specific lack of activation of the left occipito-temporal cortex in dyslexia particularly for reading and reading-like behaviors and for visuo-phonological tasks. Additional deficits of motor and attentional systems relevant for reading may be associated with altered functionality of dorsal left fronto-parietal cortex.

Mutation of Dcdc2 in mice leads to impairments in auditory processing and memory ability

Dyslexia is a complex neurodevelopmental disorder characterized by impaired reading ability despite normal intellect, and is associated with specific difficulties in phonological and rapid auditory processing (RAP), visual attention and working memory. Genetic variants in Doublecortin domain-containing protein 2 (DCDC2) have been associated with dyslexia, impairments in phonological processing and in short-term/working memory. The purpose of this study was to determine whether sensory and behavioral impairments can result directly from mutation of the Dcdc2 gene in mice. Several behavioral tasks, including a modified pre-pulse inhibition paradigm (to examine auditory processing), a 4/8 radial arm maze (to assess/dissociate working vs. reference memory) and rotarod (to examine sensorimotor ability and motor learning), were used to assess the effects of Dcdc2 mutation. Behavioral results revealed deficits in RAP, working memory and reference memory in Dcdc2(del2/del2) mice when compared with matched wild types. Current findings parallel clinical research linking genetic variants of DCDC2 with specific impairments of phonological processing and memory ability.

The visual magnocellular deficit in Chinese-speaking children with developmental dyslexia

Many alphabetic studies have evidenced that individuals with developmental dyslexia (DD) have deficits in visual magnocellular (M) pathway. However, there are few studies to investigate the M function of Chinese DD. Chinese is a logographic language, and Chinese characters are complicated in structure. Visual skills and orthographic processing abilities are particularly important for efficient reading in Chinese as compared to alphabetic languages. Therefore, it is necessary to investigate the visual M function of Chinese DD and whether the M function was associated with orthographic skills. In the present study, 26 dyslexic children (mean age: 10.03 years) and 27 age-matched normal children (mean age: 10.37 years) took part in a coherent motion (CM) detection task and an orthographic awareness test. The results showed that dyslexic children had a significantly higher threshold than age-matched children in CM detection task. Meanwhile, children with DD responded more slowly in orthographic awareness test, although the group difference was marginally significant. The results suggested that Chinese dyslexics had deficits both in visual M pathway processing and orthographic processing. In order to investigate the relationship between M function and orthographic skills, we made a correlation analysis between CM threshold and orthographic awareness by merging performance of dyslexic children and age-matched children. The results revealed that CM thresholds were positively correlated with reaction times in orthographic awareness test, suggesting that better M function was related to better orthographic processing skills.

Resolução temporal auditiva na migrânea menstrual

Objetivo verificar o comportamento auditivo de resolução temporal em mulheres com Migrânea Menstrual. Métodos participaram 40 mulheres, na faixa etária de 18 a 31 anos, das quais 20 apresentaram migrânea menstrual (grupo estudo) e 20 não apresentaram (grupo controle). Todas foram submetidas a procedimentos que fazem parte da rotina audiológica para caracterizar a audição periférica e excluir pessoas com perdas auditivas. Ainda, foram submetidas a um questionário elaborado pela pesquisadora e a uma aplicação do teste Gap in noise. Os procedimentos foram realizados na fase subfolicular precoce e na subfase lútea tardia para voluntárias que não faziam uso de anticoncepcional, uma vez que nestas fases a taxa de hormônios femininos esta mais elevada e semelhante daquelas que faziam uso de anticoncepcional. Resultados os valores dos limiares de gap e porcentagem de acertos da orelha esquerda, no grupo de estudo foram significantemente e estatisticamente diferentes em relação ao grupo controle. Em relação à orelha direita, os achados foram similares entre os grupos. Conclusão a resolução temporal em mulheres com migrânea menstrual, medida a um segmento de ruído, na orelha direita foi semelhante à das mulheres sem essa queixa, já na orelha esquerda os grupos se diferenciaram e os com migrânea obtiveram os piores limiares.

Auditory temporal structure processing in dyslexia: processing of prosodic phrase boundaries is not impaired in children with dyslexia

Reading disability in children with dyslexia has been proposed to reflect impairment in auditory timing perception. We investigated one aspect of timing perception--temporal grouping--as present in prosodic phrase boundaries of natural speech, in age-matched groups of children, ages 6-8 years, with and without dyslexia. Prosodic phrase boundaries are characterized by temporal grouping of functionally related speech elements and can facilitate syntactic processing of speech. For example, temporary syntactic ambiguities, such as early-closure structures, are processed faster when prosodic phrase boundaries are present. We examined children's prosodic facilitation by measuring their efficiency of sentence processing for temporary syntactic ambiguities spoken with (facilitating) versus without (neutral) prosodic phrase boundaries. Both groups of children benefited similarly from prosodic facilitation, displaying faster reaction times in facilitating compared to neutral prosody. These findings indicate that the use of prosodic phrase boundaries for speech processing is not impaired in children with dyslexia.

From temporal processing to developmental language disorders: mind the gap

The 'rapid temporal processing' and the 'temporal sampling framework' hypotheses have been proposed to account for the deficits in language and literacy development seen in specific language impairment and dyslexia. This paper reviews these hypotheses and concludes that the proposed causal chains between the presumed auditory processing deficits and the observed behavioural manifestation of the disorders are vague and not well established empirically. Several problems and limitations are identified. Most data concern correlations between distantly related tasks, and there is considerable heterogeneity and variability in performance as well as concerns about reliability and validity. Little attention is paid to the distinction between ostensibly perceptual and metalinguistic tasks or between implicit and explicit modes of performance, yet measures are assumed to be pure indicators of underlying processes or representations. The possibility that diagnostic categories do not refer to causally and behaviourally homogeneous groups needs to be taken seriously, taking into account genetic and neurodevelopmental studies to construct multiple-risk models. To make progress in the field, cognitive models of each task must be specified, including performance domains that are predicted to be deficient versus intact, testing multiple indicators of latent constructs and demonstrating construct reliability and validity.

Reading into neuronal oscillations in the visual system: implications for developmental dyslexia

While phonological impairments are common in developmental dyslexia, there has recently been much debate as to whether there is a causal link between the phonological difficulties and the reading problem. An alternative suggestion has been gaining ground that the core deficit in dyslexia is in visual attentional mechanisms. If so, the visual aetiology may be at any of a number of sites along the afferent magnocellular pathway or in the dorsal cortical stream that are all essential for a visuo-spatial attentional feedback to the primary visual cortex. It has been suggested that the same circuits and pathways of top-down attention used for serial visual search are used for reading. Top-down signals from the dorsal parietal areas to primary visual cortex serially highlight cortical locations representing successive letters in a text before they can be recognized and concatenated into a word. We had shown in non-human primates that the mechanism of such a top-down feedback in a visual attention task uses synchronized neuronal oscillations at the lower end of the gamma frequency range. It is no coincidence that reading graphemes in a text also happens at the low gamma frequencies. The basic proposal here is that each cycle of gamma oscillation focuses an attentional spotlight on the primary visual cortical representation of just one or two letters before sequential recognition of letters and their concatenation into word strings. The timing, period, envelope, amplitude, and phase of the synchronized oscillations modulating the incoming signals in the striate cortex would have a profound influence on the accuracy and speed of reading. Thus, the general temporal sampling difficulties in dyslexic subjects may impact reading not necessarily by causing phonological deficits, but by affecting the spatio-temporal parsing of the visual input within the visual system before these signals are used for letter and word recognition.

Musical, language, and reading abilities in early Portuguese readers

Early language and reading abilities have been shown to correlate with a variety of musical skills and elements of music perception in children. It has also been shown that reading impaired children can show difficulties with music perception. However, it is still unclear to what extent different aspects of music perception are associated with language and reading abilities. Here we investigated the relationship between cognitive-linguistic abilities and a music discrimination task that preserves an ecologically valid musical experience. 43 Portuguese-speaking students from an elementary school in Brazil participated in this study. Children completed a comprehensive cognitive-linguistic battery of assessments. The music task was presented live in the music classroom, and children were asked to code sequences of four sounds on the guitar. Results show a strong relationship between performance on the music task and a number of linguistic variables. A principle component analysis of the cognitive-linguistic battery revealed that the strongest component (Prin1) accounted for 33% of the variance and Prin1 was significantly related to the music task. Highest loadings on Prin1 were found for reading measures such as Reading Speed and Reading Accuracy. Interestingly, 22 children recorded responses for more than four sounds within a trial on the music task, which was classified as Superfluous Responses (SR). SR was negatively correlated with a variety of linguistic variables and showed a negative correlation with Prin1. When analyzing children with and without SR separately, only children with SR showed a significant correlation between Prin1 and the music task. Our results provide implications for the use of an ecologically valid music-based screening tool for the early identification of reading disabilities in a classroom setting.

The relationship between phonological and auditory processing and brain organization in beginning readers

We employed brain-behavior analyses to explore the relationship between performance on tasks measuring phonological awareness, pseudoword decoding, and rapid auditory processing (all predictors of reading (dis)ability) and brain organization for print and speech in beginning readers. For print-related activation, we observed a shared set of skill-correlated regions, including left hemisphere temporoparietal and occipitotemporal sites, as well as inferior frontal, visual, visual attention, and subcortical components. For speech-related activation, shared variance among reading skill measures was most prominently correlated with activation in left hemisphere inferior frontal gyrus and precuneus. Implications for brain-based models of literacy acquisition are discussed.

Altered neuronal response during rapid auditory processing and its relation to phonological processing in prereading children at familial risk for dyslexia

Developmental dyslexia (DD) is a learning disability affecting 5-17% of children. Although researchers agree that DD is characterized by deficient phonological processing (PP), its cause is debated. It has been suggested that altered rapid auditory processing (RAP) may lead to deficient PP in DD and studies have shown deficient RAP in individuals with DD. Functional neuroimaging (fMRI) studies have implicated hypoactivations in left prefrontal brain regions during RAP in individuals with DD. When and how these neuronal alterations evolve remains unknown. In this article, we investigate functional networks during RAP in 28 children with (n = 14) and without (n = 14) a familial risk for DD before reading onset (mean: 5.6 years). Results reveal functional alterations in left-hemispheric prefrontal regions during RAP in prereading children at risk for DD, similar to findings in individuals with DD. Furthermore, activation during RAP in left prefrontal regions positively correlates with prereading measures of PP and with neuronal activation during PP in posterior dorsal and ventral brain areas. Our results suggest that neuronal differences during RAP predate reading instruction and thus are not due to experience-dependent brain changes resulting from DD itself and that there is a functional relationship between neuronal networks for RAP and PP within the prereading brain.

Cortical basis for dichotic pitch perception in developmental dyslexia

The current study examined auditory processing deficits in dyslexia using a dichotic pitch stimulus and functional MRI. Cortical activation by the dichotic pitch task occurred in bilateral Heschl's gyri, right planum temporale, and right superior temporal sulcus. Adolescents with dyslexia, relative to age-matched controls, illustrated greater activity in left Heschl's gyrus for random noise, less activity in right Heschl's gyrus for all auditory conditions, and less activity in right superior temporal sulcus for a dichotic melody. Subsequent analyses showed that these group differences were attributable to dyslexic readers who performed poorly on the psychophysical task. Furthermore, behavioral performance on phonological reading was correlated to activity from dichotic conditions in right Heschl's gyrus and right superior temporal sulcus. It is postulated that these differences between reader groups is primarily due to a noise exclusion deficit shown previously in dyslexia.

Sex-dependent hemispheric asymmetries for processing frequency-modulated sounds in the primary auditory cortex of the mustached bat

Species-specific vocalizations of mammals, including humans, contain slow and fast frequency modulations (FMs) as well as tone and noise bursts. In this study, we established sex-specific hemispheric differences in the tonal and FM response characteristics of neurons in the Doppler-shifted constant-frequency processing area in the mustached bat's primary auditory cortex (A1). We recorded single-unit cortical activity from the right and left A1 in awake bats in response to the presentation of tone bursts and linear FM sweeps that are contained within their echolocation and/or communication sounds. Peak response latencies to neurons' preferred or best FMs were significantly longer on the right compared with the left in both sexes, and in males this right-left difference was also present for the most excitatory tone burst. Based on peak response magnitudes, right hemispheric A1 neurons in males preferred low-rate, narrowband FMs, whereas those on the left were less selective, responding to FMs with a variety of rates and bandwidths. The distributions of parameters for best FMs in females were similar on the two sides. Together, our data provide the first strong physiological support of a sex-specific, spectrotemporal hemispheric asymmetry for the representation of tones and FMs in a nonhuman mammal. Specifically, our results demonstrate a left hemispheric bias in males for the representation of a diverse array of FMs differing in rate and bandwidth. We propose that these asymmetries underlie lateralized processing of communication sounds and are common to species as divergent as bats and humans.

Dysfunction of the auditory thalamus in developmental dyslexia

Developmental dyslexia, a severe and persistent reading and spelling impairment, is characterized by difficulties in processing speech sounds (i.e., phonemes). Here, we test the hypothesis that these phonological difficulties are associated with a dysfunction of the auditory sensory thalamus, the medial geniculate body (MGB). By using functional MRI, we found that, in dyslexic adults, the MGB responded abnormally when the task required attending to phonemes compared with other speech features. No other structure in the auditory pathway showed distinct functional neural patterns between the two tasks for dyslexic and control participants. Furthermore, MGB activity correlated with dyslexia diagnostic scores, indicating that the task modulation of the MGB is critical for performance in dyslexics. These results suggest that deficits in dyslexia are associated with a failure of the neural mechanism that dynamically tunes MGB according to predictions from cortical areas to optimize speech processing. This view on task-related MGB dysfunction in dyslexics has the potential to reconcile influential theories of dyslexia within a predictive coding framework of brain function.

Cortical asymmetries in speech perception: what's wrong, what's right and what's left?

Over the past 30 years hemispheric asymmetries in speech perception have been construed within a domain-general framework, according to which preferential processing of speech is due to left-lateralized, non-linguistic acoustic sensitivities. A prominent version of this argument holds that the left temporal lobe selectively processes rapid/temporal information in sound. Acoustically, this is a poor characterization of speech and there has been little empirical support for a left-hemisphere selectivity for these cues. In sharp contrast, the right temporal lobe is demonstrably sensitive to specific acoustic properties. We suggest that acoustic accounts of speech sensitivities need to be informed by the nature of the speech signal and that a simple domain-general vs. domain-specific dichotomy may be incorrect.

Neural correlates of temporal auditory processing in developmental dyslexia during German vowel length discrimination: an fMRI study

This fMRI study investigated phonological vs. auditory temporal processing in developmental dyslexia by means of a German vowel length discrimination paradigm (Groth, Lachmann, Riecker, Muthmann, & Steinbrink, 2011). Behavioral and fMRI data were collected from dyslexics and controls while performing same-different judgments of vowel duration in two experimental conditions. In the temporal, but not in the phonological condition, hemodynamic brain activation was observed bilaterally within the anterior insular cortices in both groups and within the left inferior frontal gyrus (IFG) in controls, indicating that the left IFG and the anterior insular cortices are part of a neural network involved in temporal auditory processing. Group subtraction analyses did not demonstrate significant effects. However, in a subgroup analysis, participants performing low in the temporal condition (all dyslexic) showed decreased activation of the insular cortices and the left IFG, suggesting that this processing network might form the neural basis of temporal auditory processing deficits in dyslexia.

Sex differences in auditory subcortical function

OBJECTIVE

Sex differences have been demonstrated in the peripheral auditory system as well as in higher-level cognitive processing. Here, we aimed to determine if the subcortical response to a complex auditory stimulus is encoded differently between the sexes.

METHODS

Using electrophysiological techniques, we assessed the auditory brainstem response to a synthesized stop-consonant speech syllable [da] in 76 native-English speaking, young adults (38 female). Timing and frequency components of the response were compared between males and females to determine which aspects of the response are affected by sex.

RESULTS

A dissimilarity between males and females was seen in the neural response to the components of the speech stimulus that change rapidly over time; but not in the slower changing, lower frequency information in the stimulus. We demonstrate that, in agreement with the click-evoked brainstem response, females have earlier peaks relative to males in the subcomponents of the response representing the onset of the speech sound. In contrast, the response peaks comprising the frequency-following response, which encode the fundamental frequency (F(0)) of the stimulus, as well as the spectral amplitude of the response to the F(0), is not affected by sex. Notably, the higher-frequency elements of the speech syllable are encoded differently between males and females, with females having greater representation of spectrotemporal information for frequencies above the F(0).

CONCLUSIONS

Our results provide a baseline for interpreting the higher incidence of language impairment (e.g. dyslexia, autism, specific language impairment) in males, and the subcortical deficits associated with these disorders.

SIGNIFICANCE

These results parallel the subcortical encoding patterns that are documented for good and poor readers in that poor readers differ from good readers on encoding fast but not slow components of speech. This parallel may thus help to explain the higher incidence of reading impairment in males compared to females.

Temporal resolution with click and pure tone stimuli in youngsters with normal hearing sensitivity

PURPOSE: To assess the auditory ability of temporal resolution and to compare the random gap detection test (RGDT) versions with pure tone and clicks stimuli. METHODS: Participants were 40 young individuals of both genders with ages between 18 and 25 years, and normal hearing thresholds for the sound frequencies of 250 Hz to 8 kHz. Initially, participants were submitted to the basic audiological evaluation. Then they underwent the RGDT with pure tone and clicks stimuli. Finally, we obtained the temporal acuity threshold, which corresponds to the shorter silence interval in which the patient perceives two sounds, for each type of stimulus, called final temporal acuity threshold for pure tones (mean of the thresholds obtained for 500 Hz, 1k, 2k and 4 kHz), and temporal acuity threshold for clicks. RESULTS: The mean temporal acuity threshold for the sound frequency of 500 Hz was 7.25 ms; for the frequency of 1 kHz was 7.25 ms; for 2 kHz was 6.73 ms; for the frequency of 4 kHz was 6.03 ms. The final temporal acuity threshold was 6.72 ms. The mean temporal acuity threshold for clicks was 6.43 ms. No difference was found between the temporal acuity thresholds obtained with pure tone and clicks stimuli. CONCLUSION: There is no difference in the performance of individuals on the auditory ability of temporal resolution, regardless of the auditory stimulus used.

O uso de um software na (re)habilitação de crianças com deficiência auditiva

OBJETIVO: Verificar a aplicabilidade de um software na (re)habilitação de crianças com deficiência auditiva. MÉTODOS: A amostra foi composta por 17 crianças com deficiência auditiva, sendo dez usuárias de Implante Coclear (IC) e sete usuárias de Aparelho de Amplificação Sonora Individual (AASI). Foi utilizado o "Software Auxiliar na Reabilitação de Distúrbios Auditivos (SARDA)". Aplicou-se o protocolo de treinamento durante 30 minutos, duas vezes por semana, pelo tempo necessário para a finalização das estratégias que compõe software. Para mensurar a aplicabilidade do software no treinamento da habilidade de percepção da fala no silêncio e no ruído, foram realizadas avaliações com o Hearing in Noise Test (HINT) pré e pós o treinamento auditivo. Os dados foram analisados estatisticamente. RESULTADOS: O grupo de usuários de IC necessitou em média 12,2 dias para finalizar as estratégias e o grupo de usuários de AASI em média 10,14 dias. Os dois grupos apresentaram diferença entre as avaliações pré e pós no silêncio e no ruído. As crianças mais novas apresentaram maior dificuldade durante a execução das estratégias, porém não houve correlação entre a idade e o desempenho. Não houve influência do tipo do dispositivo eletrônico durante o treinamento. As crianças apresentaram maior dificuldade na estratégia que envolvia estímulos não verbais e na estratégia com estímulos verbais que treina a habilidade de atenção sustentada. A atenção e a motivação da criança durante a estimulação foram fundamentais para o bom rendimento do treinamento auditivo. CONCLUSÃO: O treinamento auditivo com o SARDA foi eficaz, pois propiciou melhora na habilidade de percepção da fala, no silêncio e no ruído, das crianças com deficiência auditiva.

Playing Music for a Smarter Ear: Cognitive, Perceptual and Neurobiological Evidence

Human hearing depends on a combination of cognitive and sensory processes that function by means of an interactive circuitry of bottom-up and top-down neural pathways, extending from the cochlea to the cortex and back again. Given that similar neural pathways are recruited to process sounds related to both music and language, it is not surprising that the auditory expertise gained over years of consistent music practice fine-tunes the human auditory system in a comprehensive fashion, strengthening neurobiological and cognitive underpinnings of both music and speech processing. In this review we argue not only that common neural mechanisms for speech and music exist, but that experience in music leads to enhancements in sensory and cognitive contributors to speech processing. Of specific interest is the potential for music training to bolster neural mechanisms that undergird language-related skills, such as reading and hearing speech in background noise, which are critical to academic progress, emotional health, and vocational success.

Eficácia do treinamento de habilidades fonológicas em crianças de risco para dislexia

OBJETIVOS: identificar os sinais da dislexia em escolares de 1ª série e verificar a eficácia do programa de treinamento fonológico em crianças de risco para a dislexia que freqüentam a 1ª série escolar e investigar dentre as crianças de risco que não apresentaram melhora após o treinamento se há presença do quadro de dislexia por meio de diagnóstico interdisciplinar. MÉTODO: participaram deste estudo 30 crianças de 1ª série de ensino público, de ambos os gêneros, na faixa etária de 6 a 7 anos de idade. Neste estudo foi realizada a adaptação brasileira da pesquisa sobre treinamento de habilidades fonológicas composta de pré-testagem, intervenção e pós-testagem. Em situação de pré e pós-testagem, todas as crianças foram submetidas à aplicação do teste para a identificação precoce dos problemas de leitura e aquelas que apresentaram desempenho inferior a 51% das provas do teste foram divididas em Grupo I (GI): composto por 13 crianças submetidas ao programa de treinamento; e em Grupo II (GII): composto por 17 crianças não submetidas ao programa de treinamento. RESULTADOS: os resultados deste estudo revelaram diferenças estatisticamente significantes, evidenciando que das 13 crianças submetidas ao programa, 11 apresentaram melhor desempenho em situação de pós-testagem em relação à pré-testagem. Apenas 2 crianças não responderam à intervenção proposta, sendo submetidas à avaliação interdisciplinar. CONCLUSÃO: a realização do programa de treinamento das habilidades fonológicas foi eficaz para as crianças de risco para dislexia, comprovados pela melhora das habilidades fonológicas e de leitura em situação de pós-testagem em relação à pré-testagem.

Neurokognitive Korrelate der Dyslexie

Die Überblicksarbeit widmet sich kognitiven und neuronalen Grundlagen der Dyslexie. Ausgehend von einer Darstellung der wichtigsten kognitiven und neurobiologischen Theorien der Entstehung von Dyslexie werden Ergebnisse zu spezifischen Störungen des neuronalen Lesenetzwerks bei Menschen mit Dyslexie aus Postmortem-Untersuchungen und strukturellen sowie funktionellen Bildgebungsstudien berichtet. Die Befunde legen nahe, dass Dyslexie ein multidimensionales Problem darstellt, das mit verschiedenen kognitiven, sensorischen und motorischen Defiziten und spezifischen Störungen auf neuronaler Ebene einhergeht. Zukünftige Forschung sollte sich daher verstärkt individuellen Profilen der Störung auf kognitiver wie neuronaler Ebene widmen.

Desempenho de escolares com distúrbio de aprendizagem e dislexia em testes de processamento auditivo

OBJETIVO: caracterizar e comparar, por meio de testes comportamentais, o processamento auditivo de escolares com diagnóstico interdisciplinar de (I) distúrbio da aprendizagem, (II) dislexia e (III) escolares com bom desempenho acadêmico. MÉTODOS: participaram deste estudo 30 escolares na faixa etária de 8 a 16 anos de idade, de ambos os gêneros, de 2ª a 4ª séries do ensino fundamental, divididos em três grupos: GI composto por 10 escolares com diagnóstico interdisciplinar de distúrbio de aprendizagem, GII: composto por 10 escolares com diagnóstico interdisciplinar de dislexia e GIII composto por 10 escolares sem dificuldades de aprendizagem, pareados segundo gênero e faixa etária com os grupos GI e GII. Foram realizadas avaliação audiológica e de processamento auditivo. RESULTADOS: os escolares de GIII apresentaram desempenho superior nos testes de processamento auditivo em relação aos escolares de GI e GII. GI apresentou desempenho inferior nas habilidades auditivas avaliadas para testes dicóticos de dígitos e dissílabos alternados, logoaudiometria pediátrica, localização sonora, memória verbal e não-verbal, ao passo que GII apresentou as mesmas alterações de GI, com exceção do teste de logoaudiometria pediátrica. CONCLUSÃO: os escolares com transtornos de aprendizagem apresentaram desempenho inferior nos testes de processamento auditivo, sendo que os escolares com distúrbio de aprendizagem apresentaram maior número de habilidades auditivas alteradas, em comparação com os escolares com dislexia, por terem apresentado atenção sustentada reduzida. O grupo de escolares com dislexia apresentou alterações decorrentes da dificuldade relacionada à codificação e decodificação de estímulos sonoros.