Alteraciones del procesamiento preléxico en pacientes hispanohablantes con afasias sensoriales: evidencias neurolingüísticas / Prelexical processing alterations in hispanophone patients with sensitive aphasias: neurolinguistic evidences

La verificación empírica de modelos de conversión acústico-fonémica es una necesidad de la práctica de la neurolingüística en cualquier contexto para optimizar la explicación del patrón neurocognitivo de pacientes con alteraciones del procesamiento preléxico. Por tal razón, en esta investigación se caracterizan los procesos de conversión acústico-fonémica en pacientes hispanohablantes, con el objetivo de obtener y acumular evidencias empíricas que permitan verificar en esta población lingüística el modelo de procesamiento preléxico más aceptado actualmente. Para ello se realizó un estudio descriptivo-transversal, con la participación de 72 pacientes con afasia de comprensión pertenecientes a los Servicios de Logofoniatría de la ciudad de Santiago de Cuba, con edades de 20 a 65 años, y entre 60 y 180 días de recuperación del daño cerebral. Estos fueron sometidos al Test de discriminación fonológica, que es una adaptación local de la «Prueba de discriminación» del Test DIFO de Benedet y Cortés-del-Solar. Se obtuvo que las alteraciones del procesamiento de las características distintivas de los sonidos del habla se distinguen de las alteraciones de la integración perceptual de fonemas. En el primer caso, se registran fallos estables en la ejecución de tareas que implican el procesamiento de unos u otros rasgos distintivos de los sonidos consonánticos del habla, mientras se conserva el procesamiento de rasgos distintivos de los sonidos vocálicos, y viceversa. En el segundo caso, se observan fallos en el procesamiento, tanto de todos los rasgos distintivos de los sonidos consonánticos del habla, como de los rasgos distintivos de los sonidos vocálicos (AU)

The empirical verification of prelexical processing models is necessary for the neurolinguistic practices in any context for optimizing the explanations of neurocognitive model in aphasic patients with disorder in prelexical processing. For this reason, the present investigation shows the characterization of acoustic-phonemic conversion process in aphasic hispanophone patients. The study was executed with the purpose to accumulate and to obtain empirical evidences in this linguistic population, for the practical verification of the most accepted prelexical processing model. A descriptive-transversal study was conducted with the participation of 72 patients with sensitive aphasia, localized in the Phoniatry Services of Santiago de Cuba City, with ages between 20 and 65 years, and not more of 60 to 180 days of brain injury recovery period. The participants performed the Test de discriminación fonológica, that is a contextual adaptation of the task «Prueba de discriminación» of the Test DIFO of Benedet and Cortés-del-Solar. Results revealed that disorders in distinctive characteristics of speech sounds processing are different of phoneme perceptual integration disorders. In the first, affectation in the execution of tasks that implies the processing of some distinctive characteristics of consonant speech sounds was recorded, whereas the processing of other distinctive characteristics of vowel speech sounds are preserved. In the second affectation in the processing of all distinctive characteristics of speech sounds was observed (AU)

Auditory Processing in Children with Migraine: A Controlled Study.

Background This study aimed to investigate central auditory processing performance in children with migraine and compared with controls without headache. Methods Twenty-eight children of both sexes, aged between 8 and 12 years, diagnosed with migraine with and without aura, and a control group of the same age range and with no headache history, were included. Gaps-in-noise (GIN), duration pattern test (DPT), synthetic sentence identification (SSI) test, and nonverbal dichotic test (NVDT) were used to assess central auditory processing performance. Results Children with migraine performed significantly worse in DPT, SSI test, and NVDT when compared with controls without headache; however, no significant differences were found in the GIN test. Conclusions Children with migraine demonstrate impairment in the physiologic mechanism of temporal processing and selective auditory attention. In our short communication, migraine could be related to impaired central auditory processing in children.

Classifying song and speech: effects of focal temporal lesions and musical disorder.

Song and speech represent two auditory categories the brain usually classifies fairly easily. Functionally, this classification ability may depend to a great extent on characteristic features of pitch patterns present in song melody and speech prosody. Anatomically, the temporal lobe (TL) has been discussed as playing a prominent role in the processing of both. Here we tested individuals with congenital amusia and patients with unilateral left and right TL lesions in their ability to categorize song and speech. In a forced-choice paradigm, specifically designed auditory stimuli representing sung, spoken and "ambiguous" stimuli (being perceived as "halfway between" song and speech), had to be classified as either "song" or "speech". Congenital amusics and TL patients, contrary to controls, exhibited a surprising bias to classifying the ambiguous stimuli as "song" despite their apparent deficit to correctly process features typical for song. This response bias possibly reflects a strategy where, based on available context information (here: forced choice for either speech or song), classification of non-processable items may be achieved through elimination of processable classes. This speech-based strategy masks the pitch processing deficit in congenital amusics and TL lesion patients.

Pitch-Responsive Cortical Regions in Congenital Amusia.

Congenital amusia is a lifelong deficit in music perception thought to reflect an underlying impairment in the perception and memory of pitch. The neural basis of amusic impairments is actively debated. Some prior studies have suggested that amusia stems from impaired connectivity between auditory and frontal cortex. However, it remains possible that impairments in pitch coding within auditory cortex also contribute to the disorder, in part because prior studies have not measured responses from the cortical regions most implicated in pitch perception in normal individuals. We addressed this question by measuring fMRI responses in 11 subjects with amusia and 11 age- and education-matched controls to a stimulus contrast that reliably identifies pitch-responsive regions in normal individuals: harmonic tones versus frequency-matched noise. Our findings demonstrate that amusic individuals with a substantial pitch perception deficit exhibit clusters of pitch-responsive voxels that are comparable in extent, selectivity, and anatomical location to those of control participants. We discuss possible explanations for why amusics might be impaired at perceiving pitch relations despite exhibiting normal fMRI responses to pitch in their auditory cortex: (1) individual neurons within the pitch-responsive region might exhibit abnormal tuning or temporal coding not detectable with fMRI, (2) anatomical tracts that link pitch-responsive regions to other brain areas (e.g., frontal cortex) might be altered, and (3) cortical regions outside of pitch-responsive cortex might be abnormal. The ability to identify pitch-responsive regions in individual amusic subjects will make it possible to ask more precise questions about their role in amusia in future work.

Mismatch negativity in tobacco-naïve cannabis users and its alteration with acute nicotine administration.

Chronic cannabis use may interact with factors, such as age of onset of cannabis use, family history, and genetic factors, to elicit schizophrenia (SZ)-like symptoms, including sensory and cognitive deficits. However, evidence of a relationship between cannabis use and cognitive impairment is confounded by concomitant use of tobacco. The objective of this study was to compare tobacco-naïve cannabis users with individuals without a history of tobacco/cannabis use on the auditory mismatch negativity (MMN) event-related potential (ERP), a neural measure of auditory deviance detection which is diminished in SZ. An exploratory arm of the study, conducted within a randomized, double-blind, placebo controlled design, examined the acute effects of nicotine gum (6mg) on MMN in cannabis users. MMN was recorded in response to 5 deviant stimuli within an optimal MMN paradigm in 44 healthy, non-tobacco smoking volunteers aged 18-26. Cannabis users (n=21) started smoking cannabis prior to age 17, at least 1 joint per month. To examine the effects of chronicity, users were grouped into relatively heavy long-term (HLT; n=11) users and light short-term (LST; n=10) users. Impaired deviance detection was shown in cannabis users vs. nonusers as reflected by a smaller MMN to duration deviants. Chronicity of use was also associated with MMN alterations, as HLTs displayed a reduced duration and gap MMN vs. LSTs. Compared with placebo, nicotine treatment enhanced select MMN deviants in cannabis user subgroups. As deficits associated with early and persistent cannabis use are similar to those seen in SZ, these dose-dependant disturbances in early sensory processing with cannabis use may be one cognitive pathway which mediates an increased risk for SZ in vulnerable youth, and be influenced by concurrent cigarette smoking behavior.

Association between language development and auditory processing disorders.

INTRODUCTION: It is crucial to understand the complex processing of acoustic stimuli along the auditory pathway; comprehension of this complex processing can facilitate our understanding of the processes that underlie normal and altered human communication. AIM: To investigate the performance and lateralization effects on auditory processing assessment in children with specific language impairment (SLI), relating these findings to those obtained in children with auditory processing disorder (APD) and typical development (TD). MATERIAL AND METHODS: Prospective study. Seventy-five children, aged 6-12 years, were separated in three groups: 25 children with SLI, 25 children with APD, and 25 children with TD. All went through the following tests: speech-in-noise test, Dichotic Digit test and Pitch Pattern Sequencing test. RESULTS: The effects of lateralization were observed only in the SLI group, with the left ear presenting much lower scores than those presented to the right ear. The inter-group analysis has shown that in all tests children from APD and SLI groups had significantly poorer performance compared to TD group. Moreover, SLI group presented worse results than APD group. CONCLUSION: This study has shown, in children with SLI, an inefficient processing of essential sound components and an effect of lateralization. These findings may indicate that neural processes (required for auditory processing) are different between auditory processing and speech disorders.

Association between language development and auditory processing disorders / Associação entre transtornos no desenvolvimento de linguagem e processamento auditivo

INTRODUCTION: It is crucial to understand the complex processing of acoustic stimuli along the auditory pathway ;comprehension of this complex processing can facilitate our understanding of the processes that underlie normal and altered human communication. AIM: To investigate the performance and lateralization effects on auditory processing assessment in children with specific language impairment (SLI), relating these findings to those obtained in children with auditory processing disorder (APD) and typical development (TD). MATERIAL AND METHODS: Prospective study. Seventy-five children, aged 6-12 years, were separated in three groups: 25 children with SLI, 25 children with APD, and 25 children with TD. All went through the following tests: speech-in-noise test, Dichotic Digit test and Pitch Pattern Sequencing test. RESULTS: The effects of lateralization were observed only in the SLI group, with the left ear presenting much lower scores than those presented to the right ear. The inter-group analysis has shown that in all tests children from APD and SLI groups had significantly poorer performance compared to TD group. Moreover, SLI group presented worse results than APD group. CONCLUSION: This study has shown, in children with SLI, an inefficient processing of essential sound components and an effect of lateralization. These findings may indicate that neural processes (required for auditory processing) are different between auditory processing and speech disorders. .

INTRODUÇÃO: Entender como os estímulos acústicos são processados ao longo da via auditiva é fundamental para compreender os processos que subjazem à comunicação humana normal e alterada. OBJETIVO: Investigar o desempenho e efeitos de lateralidade na avaliação do processamento auditivo em crianças com distúrbio específico de linguagem (DEL), comparando os resultados obtidos aos encontrados em crianças com transtorno de processamento auditivo (TPA) e desenvolvimento típico (DT). MATERIAL E MÉTODO: Estudo Prospectivo. 75 crianças (6-12 anos), divididas em três grupos (25 crianças com DEL, 25 crianças com TPA e 25 crianças em DT), foram submetidas aos seguintes testes: Teste de Figura com Ruído, Teste Dicótico de Dígitos e Teste de Padrão de Frequência. RESULTADO: Os efeitos de lateralidade foram observados apenas no grupo DEL, sendo o desempenho na orelha esquerda inferior ao apresentado na orelha direita. Na comparação intergrupos, o desempenho dos grupos TPA e DEL foi significativamente inferior ao observado no grupo DT para todos os testes. Além disso, observamos nas crianças do grupo DEL um desempenho inferior às do grupo TPA. CONCLUSÃO: Este estudo constatou o processamento ineficiente de componentes cruciais de sons e o efeito de lateralidade em crianças com DEL. Esses achados evidenciam que os processos neurais que subjazem ao processamento auditivo são diferentes entre alterações de processamento auditivo e alterações de fala. .

La transposición frecuencial. Incidencia en las habilidades de identificación y el reconocimiento auditivo en jóvenes con pérdidas auditivas profundas / Frequency transposition. Impact on identification skills, auditory comprehension, and voice quality in young adults with profound hearing loss

A partir de la necesidad de facilitar la percepción de los rasgos acústicos más agudos de los fonemas del habla, se presenta un estudio sobre los cambios observados en un grupo de jóvenes con discapacidad auditiva severa-profunda, después de utilizar la transposición frecuencial proporcionada por unos audífonos digitales Mind440-19, mediante el extensor de audibilidad. La muestra del estudio la constituyó un grupo de 7jóvenes con edades comprendidas entre los 13 y los 25años, divididos en dos grupos, en función de su configuración audiométrica. El primer grupo estuvo formado por 4participantes con una pérdida auditiva promedio de 99dB. El segundo grupo presentó una pérdida mayor, con un promedio de 105 dB para ambos oídos. El beneficio de la transposición frecuencial se comprobó mediante una batería de pruebas que incluía el test de Ling, un test de identificación y otro de reconocimiento de palabras. Las pruebas fueron administradas después de 4, 8 y 12semanas de emplear los nuevos audífonos y se compararon con los resultados obtenidos con los anteriores audífonos empleados por los participantes en este estudio, sin el extensor de audibilidad activado (AU)

Based on the need to enhance perception of more high-pitched acoustic features of speech phonemes, we present this study on the changes observed in a group of young people with severe-profound hearing impairment after trialling the frequency transposition technology of the Mind440-19 hearing aid, using the Audibility Extender. The sample of the study was a group of 7young people with ages ranging from 13 to 25years, divided into two groups based on their audiometric configuration. The first group consisted of 4subjects with a mean pure tone of 99dB. The second group had more profound hearing loss, with a mean pure tone of 105dB in both ears. Frequency transposition benefit was measured through a test battery including Ling's test, an identification test and a word recognition test. Tests were administered after 4, 8, and 12weeks of hearing aid use, and compared with results from the previous hearing aids used by the participants, with their Audibility Extender off (AU)

Not pitch perfect: sensory contributions to affective communication impairment in schizophrenia.

BACKGROUND: Schizophrenia patients have vocal affect (prosody) deficits that are treatment resistant and associated with negative symptoms and poor outcome. The neural correlates of this dysfunction are unclear. Prior study has suggested that schizophrenia vocal affect perception deficits stem from an inability to use acoustic cues, notably pitch, in decoding emotion. METHODS: Functional magnetic resonance imaging was performed in 24 schizophrenia patients and 28 healthy control subjects, during the performance of a four-choice (happiness, fear, anger, neutral) vocal affect identification task in which items for each emotion varied parametrically in affective salient acoustic cue levels. RESULTS: We observed that parametric increases in cue levels in schizophrenia failed to produce the same identification rate increases as in control subjects. These deficits correlated with diminished reciprocal activation changes in superior temporal and inferior frontal gyri and reduced temporo-frontal connectivity. Task activation also correlated with independent measures of pitch perception and negative symptom severity. CONCLUSIONS: These findings illustrate the interplay between sensory and higher-order cognitive dysfunction in schizophrenia. Sensory contributions to vocal affect deficits also suggest that this neurobehavioral marker could be targeted by pharmacological or behavioral remediation of acoustic feature discrimination.

Effect of nonlinguistic auditory training on phonological and reading skills.

OBJECTIVE: To analyze the effect of nonverbal auditory training on reading and phonological awareness tasks in children with dyslexia and the effect of age in relation to post-training learning considering the ages from 7 to 14. METHODS: In experiment 1, one group with dyslexia (total = 12) was trained and compared with a group of untrained dyslexic subjects (total = 28). In experiment 2, the performance of the trained dyslexic group (total = 18) was compared at three different moments: 2 months before, at the beginning, and at the end of training. Training was carried out for 2 months using a computer program responsible for training discrimination skills. RESULTS: The group receiving nonverbal auditory training demonstrated significant improvements (mainly for the group from 7 to 10 years old), not only in the nonverbal auditory skills trained (p < 0.001), but also in phonological awareness syllable tasks (synthesis, segmentation, manipulation and syllable transposition) in experiment 1 (p < 0.003), and phonemic tasks (p < 0.001) and text reading (p < 0.001) in experiment 2. CONCLUSION: The results suggest a link between verbal and nonverbal skills, in addition to corroborating studies regarding the existence of a critical learning period.

Transtorno do processamento auditivo (central) em indivíduos com e sem dislexia / (Central) auditory processing disorders in individuals with and without dyslexia

TEMA: comparação do transtorno do processamento auditivo (central) em indivíduos com e sem dislexia. OBJETIVO: comparar o transtorno do processamento auditivo (central) em crianças brasileiras com e sem dislexia, por meio dos testes fala com ruído, dicótico de dígitos e padrão de freqüência. MÉTODO: foram avaliadas 40 crianças de 7:0 a 12:11 anos, sendo 20 pertencentes ao grupo com dislexia e 20 pertencentes ao grupo TPA(C). Os testes aplicados envolveram habilidades de fechamento auditivo, figura-fundo para sons lingüísticos e ordenação temporal. RESULTADOS: os indivíduos do grupo TPA (C) apresentaram maior probabilidade de alteração nos testes de fala com ruído e dicótico de dígitos do que os pertencentes ao grupo dislexia. CONCLUSÃO: os sujeitos do grupo dislexia apresentam padrões diferentes de transtorno de processamento auditivo (central), com alteração maior em testes que avaliam o processamento temporal do que em testes que avaliam outras habilidades auditivas.

BACKGROUND: comparison of (central) auditory processing disorders in children with and without dyslexia. AIM: to compare the (central) auditory processing disorders in Brazilian children with and without dyslexia using speech in noise, dichotic digits and pattern of frequency tests. METHOD: forty-five children with ages ranging between 7:0 and 12:11 years were assessed; twenty children composed the dyslexic group and twenty composed the (Central) auditory processing disorder group. The tests used involved closing aural, auditory figure-ground and temporal ordering abilities. RESULTS: individuals of the (Central) auditory processing disorder group presented a higher alteration probability in the speech in noise and dichotic digits tests than those from the dyslexic group. CONCLUSION: subjects from the dyslexic group presented different patterns of (central) auditory processing disorder, with greater alteration in the tests that evaluate the temporal processing when compared to the tests that evaluate other auditory abilities.

(Central) auditory processing disorders in individuals with and without dyslexia.

BACKGROUND: Comparison of (central) auditory processing disorders in children with and without dyslexia. AIM: To compare the (central) auditory processing disorders in Brazilian children with and without dyslexia using speech in noise, dichotic digits and pattern of frequency tests. METHOD: Forty-five children with ages ranging between 7:0 and 12:11 years were assessed; twenty children composed the dyslexic group and twenty composed the (Central) auditory processing disorder group. The tests used involved closing aural, auditory figure-ground and temporal ordering abilities. RESULTS: Individuals of the (Central) auditory processing disorder group presented a higher alteration probability in the speech in noise and dichotic digits tests than those from the dyslexic group. CONCLUSION: Subjects from the dyslexic group presented different patterns of (central) auditory processing disorder, with greater alteration in the tests that evaluate the temporal processing when compared to the tests that evaluate other auditory abilities.

Canonical syllable reduplication and variegation in infants with sensorineural hearing loss

Introduction: The purpose of this study was to evaluate the effect of hearing loss on the distribution of reduplicated and variegated syllables in canonical babbling. Method: Spontaneous vocalizations of six early identified infants with mild-to-moderately severe hearing loss, and 4 infants with normal hearing sensitivity were audio-recorded and perceptually transcribed. Utterances containing well-formed multisyllabic canonical syllable sequences were selected for analysis of reduplication and variegation patterns. Results: Infants with normal hearing showed an equal proportion of reduplicated and variegated syllable sequences. However, for infants with mild to-moderately-severe hearing loss, syllable variegation exceeded reduplication. Conclusions: Auditory sensitivity may contribute significantly to the distribution of reduplicated versus variegated syllable sequences (AU)

Introducción: El objetivo de este estudio es evaluar el efecto de la pérdida de audición en la distribución dela reduplicación y mezcla de sílabas balbuceadas. Método: Se analizaron y registraron las vocalizaciones espontáneas en seis niños con pérdida de oído de leve a moderadamente severa y en cuatro niños con sensibilidad auditiva normal. Las expresiones que contienen secuencias polisilábicas gramaticalmente correctas fueron seleccionadas para el análisis de reduplicación y mezcla de sílabas balbuceadas. Resultados: Los niños con audición normal mostraron una proporción igual de las secuencias de reduplicación y mezcla de la sílaba. Sin embargo, para los niños con pérdida de oído de leve a moderadamente severa, la diversidad de sílaba excedió a la reduplicación. Conclusiones: La sensibilidad auditiva puede contribuir considerablemente a la distribución de la reduplicación de la sílaba frente a la mezcla de secuencias (AU)

Olanzapine improves deficient sensory inhibition in DBA/2 mice.

Most schizophrenia patients do not inhibit their P50 auditory evoked potential to the second of duplicate auditory stimuli, reflecting a failure to inhibit responses to irrelevant sensory input. Typical antipsychotic drugs do not improve this deficit while some atypical antipsychotics do. A previous study using an animal model, deficient P20-N40 (which corresponds to the human P50) inhibitory processing in DBA/2 mice found that sensory inhibition was improved by clozapine, the prototypical atypical antipsychotic, but not by haloperidol, a typical antipsychotic. The improvement after clozapine was mediated by alpha7 nicotinic receptors. The present study addresses whether another atypical antipsychotic, olanzapine, will also improve sensory inhibition deficits in the mouse model. In vivo electrophysiological recordings of the P20-N40 auditory evoked potential in anesthetized DBA/2 mice, which spontaneously exhibit a schizophrenia-like inhibitory processing deficit, were obtained after olanzapine alone (0.01, 0.033, 0.1, 0.33 mg/kg, IP) and the efficacious dose of olanzapine (0.033 mg/kg, IP) in combination with either the alpha7 nicotinic receptor antagonist alpha-bungarotoxin or the alpha4beta2 nicotinic receptor antagonist di-hydro-beta-erythroidine. All doses of olanzapine produced improved P20-N40 inhibitory processing in DBA/2 mice. The normalization observed after the 0.033 mg/kg dose of olanzapine was due to a selective decrease in response to the second auditory stimulus indicating an increase in inhibitory processing. This improvement was blocked by pre-administration of alpha-bungarotoxin but not di-hydro-beta-erythroidine. Like clozapine, olanzapine acts via alpha7 nicotinic receptors to elicit improved inhibitory processing of auditory stimuli.

Children with specific language impairment also show impairment of music-syntactic processing.

Both language and music consist of sequences that are structured according to syntactic regularities. We used two specific event-related brain potential (ERP) components to investigate music-syntactic processing in children: the ERAN (early right anterior negativity) and the N5. The neural resources underlying these processes have been posited to overlap with those involved in the processing of linguistic syntax. Thus, we expected children with specific language impairment (SLI, which is characterized by deficient processing of linguistic syntax) to demonstrate difficulties with music-syntactic processing. Such difficulties were indeed observed in the neural correlates of music-syntactic processing: neither an ERAN nor an N5 was elicited in children with SLI, whereas both components were evoked in age-matched control children with typical language development. Moreover, the amplitudes of ERAN and N5 were correlated with subtests of a language development test. These data provide evidence for a strong interrelation between the language and the music processing system, thereby setting the ground for possible effects of musical training in SLI therapy.

Audio-vocal system regulation in children with autism spectrum disorders.

Do children with autism spectrum disorders (ASD) respond similarly to perturbations in auditory feedback as typically developing (TD) children? Presentation of pitch-shifted voice auditory feedback to vocalizing participants reveals a close coupling between the processing of auditory feedback and vocal motor control. This paradigm was used to test the hypothesis that abnormalities in the audio-vocal system would negatively impact ASD compensatory responses to perturbed auditory feedback. Voice fundamental frequency (F(0)) was measured while children produced an /a/ sound into a microphone. The voice signal was fed back to the subjects in real time through headphones. During production, the feedback was pitch shifted (-100 cents, 200 ms) at random intervals for 80 trials. Averaged voice F(0) responses to pitch-shifted stimuli were calculated and correlated with both mental and language abilities as tested via standardized tests. A subset of children with ASD produced larger responses to perturbed auditory feedback than TD children, while the other children with ASD produced significantly lower response magnitudes. Furthermore, robust relationships between language ability, response magnitude and time of peak magnitude were identified. Because auditory feedback helps to stabilize voice F(0) (a major acoustic cue of prosody) and individuals with ASD have problems with prosody, this study identified potential mechanisms of dysfunction in the audio-vocal system for voice pitch regulation in some children with ASD. Objectively quantifying this deficit may inform both the assessment of a subgroup of ASD children with prosody deficits, as well as remediation strategies that incorporate pitch training.

Auditory processing disorder in children with reading disabilities: effect of audiovisual training.

Reading disability is associated with phonological problems which might originate in auditory processing disorders. The aim of the present study was 2-fold: first, the perceptual skills of average-reading children and children with dyslexia were compared in a categorical perception task assessing the processing of a phonemic contrast based on voice onset time (VOT). The medial olivocochlear (MOC) system, an inhibitory pathway functioning under central control, was also explored. Secondly, we investigated whether audiovisual training focusing on voicing contrast could modify VOT sensitivity and, in parallel, induce MOC system plasticity. The results showed an altered voicing sensitivity in some children with dyslexia, and that the most severely impaired children presented the most severe reading difficulties. These deficits in VOT perception were sometimes accompanied by MOC function abnormalities, in particular a reduction in or even absence of the asymmetry in favour of the right ear found in average-reading children. Audiovisual training significantly improved reading and shifted the categorical perception curve of certain children with dyslexia towards the average-reading children's pattern of voicing sensitivity. Likewise, in certain children MOC functioning showed increased asymmetry in favour of the right ear following audiovisual training. The training-related improvements in reading score were greatest in children presenting the greatest changes in MOC lateralization. Taken together, these results confirm the notion that some auditory system processing mechanisms are impaired in children with dyslexia and that audiovisual training can diminish these deficits.

Infant information processing and family history of specific language impairment: converging evidence for RAP deficits from two paradigms.

An infant's ability to process auditory signals presented in rapid succession (i.e. rapid auditory processing abilities [RAP]) has been shown to predict differences in language outcomes in toddlers and preschool children. Early deficits in RAP abilities may serve as a behavioral marker for language-based learning disabilities. The purpose of this study is to determine if performance on infant information processing measures designed to tap RAP and global processing skills differ as a function of family history of specific language impairment (SLI) and/or the particular demand characteristics of the paradigm used. Seventeen 6- to 9-month-old infants from families with a history of specific language impairment (FH+) and 29 control infants (FH-) participated in this study. Infants' performance on two different RAP paradigms (head-turn procedure [HT] and auditory-visual habituation/recognition memory [AVH/RM]) and on a global processing task (visual habituation/recognition memory [VH/RM]) was assessed at 6 and 9 months. Toddler language and cognitive skills were evaluated at 12 and 16 months. A number of significant group differences were seen: FH+ infants showed significantly poorer discrimination of fast rate stimuli on both RAP tasks, took longer to habituate on both habituation/recognition memory measures, and had lower novelty preference scores on the visual habituation/recognition memory task. Infants' performance on the two RAP measures provided independent but converging contributions to outcome. Thus, different mechanisms appear to underlie performance on operantly conditioned tasks as compared to habituation/recognition memory paradigms. Further, infant RAP processing abilities predicted to 12- and 16-month language scores above and beyond family history of SLI. The results of this study provide additional support for the validity of infant RAP abilities as a behavioral marker for later language outcome. Finally, this is the first study to use a battery of infant tasks to demonstrate multi-modal processing deficits in infants at risk for SLI.

Abnormal speech sound representation in persistent developmental stuttering.

OBJECTIVES: To determine whether adults with persistent developmental stuttering (PDS) have auditory perceptual deficits. METHODS: The authors compared the mismatch negativity (MMN) event-related brain potential elicited to simple tone (frequency and duration) and phonetic contrasts in a sample of PDS subjects with that recorded in a sample of paired fluent control subjects. RESULTS: Subjects with developmental stuttering had normal MMN to simple tone contrasts but a significant supratemporal left-lateralized enhancement of this electrophysiologic response to phonetic contrasts. In addition, the enhanced MMN correlated positively with speech disfluency as self-rated by the subjects. CONCLUSIONS: Individuals with persistent developmental stuttering have abnormal permanent traces for speech sounds, and their abnormal speech sound representation may underlie their speech disorder. The link between abnormal speech neural traces of the auditory cortex and speech disfluency supports the relevance of speech perception mechanisms to speech production.

Magnetoencephalographic evidence of abnormal auditory processing in amyotrophic lateral sclerosis with bulbar signs.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is characterized by progressive motor neuron damage that gives rise to muscle denervation. Besides motor neuron damage, conscious auditory processing appears to be impaired in ALS, whereas it has remained ambiguous whether preceding automatic auditory processing is abnormal in ALS and specifically in ALS with bulbar signs. METHODS: Auditory evoked fields (AEFs) to monaurally presented frequent and infrequent tones with stimulus intervals of 500 and 2500 ms were recorded with magnetoencephalography (MEG) from 10 ALS patients having bulbar signs and from 10 age-matched healthy subjects. RESULTS: The amplitudes of the P50m and N100m responses, which index automatic auditory processing underlying stimulus detection, were significantly increased and P50m latency was shortened in ALS patients. MMNm, which reflects memory-based auditory comparison process, was increased in amplitude in the patient group, whereas the MMNm latency was similar in both groups. AEF latency and amplitude values failed to correlate with the severity of ALS as measured by ALS Functional Rating Scale (ALSFRS). CONCLUSIONS: The present results suggest that auditory processing underlying stimulus detection, and subsequent memory-based comparison processes are abnormal in ALS patients with severe bulbar signs. This might be due to cortical overactivity of excitatory neurotransmitter glutamate observed in ALS.