Exposure to sign language prior and after cochlear implantation increases language and cognitive skills in deaf children.

Recent evidence suggests that deaf children with CIs exposed to nonnative sign language from hearing parents can attain age-appropriate vocabularies in both sign and spoken language. It remains to be explored whether deaf children with CIs who are exposed to early nonnative sign language, but only up to implantation, also benefit from this input and whether these benefits also extend to memory abilities, which are strongly linked to language development. The present study examined the impact of deaf children's early short-term exposure to nonnative sign input on their spoken language and their phonological memory abilities. Deaf children who had been exposed to nonnative sign input before and after cochlear implantation were compared to deaf children who never had any exposure to sign input as well as to children with typical hearing. The children were between 5;1 and 7;1 years of age at the time of testing and were matched on age, sex, and socioeconomic status. The results suggest that even short-term exposure to nonnative sign input has positive effects on general language and phonological memory abilities as well as on nonverbal working memory-with total length of exposure to sign input being the best predictor of deaf children's performance on these measures. The present data suggest that even access to early short-term nonnative visual language input is beneficial for the language and phonological memory abilities of deaf children with cochlear implants, suggesting also that parents should not be discouraged from learning and exposing their child to sign language. RESEARCH HIGHLIGHTS: This is the first study to examine the effects of early short-term exposure to nonnative sign input on French-speaking children with cochlear implants' spoken language and memory abilities. Early short-term nonnative exposure to sign input can have positive consequences for the language and phonological memory abilities of deaf children with CIs. Extended exposure to sign input has some additional and important benefits, allowing children to perform on par with children with typical hearing.

Enhanced tactile identification of musical emotion in the deaf.

Functional neuroimaging studies have demonstrated that following deafness, auditory regions can respond to tactile stimuli. However, research to date has not conclusively demonstrated the behavioral correlates of these functional changes, with most studies showing normal-like tactile capabilities in the deaf. It has recently been suggested that more cognitive and complex tactile processes, such as music perception, could help to uncover superior tactile capabilities in the deaf. Indeed, following deafness music seems to be perceived through vibration, but the extent to which they can perceive musical features though the tactile modality remains undetermined. The goal of this study was to investigate tactile identification of musical emotion in the deaf. Participants had to rate melodies based on their emotional perception. Stimuli were presented through an haptic glove. Data suggest that deaf and control participants were comparable in the identification of three of the four emotions tested (sad, fear/threat, peacefulness). However and most importantly, for the simplest emotion (happiness), significant differences emerged between groups, suggesting an improved tactile identification of musical emotion in the deaf. Results support the hypothesis that brain plasticity following deafness can lead to improved complex tactile ability.

Audiomotor interaction induced by mental imagery.

Mental imagery can induce audiovisual integration, but whether it can induce interactions in other modalities remains uncertain. It has been demonstrated that audiomotor interaction can be generated following training, but whether such audiomotor interaction can be induced by auditory imagery training remains unknown. The present study aims at determining whether auditory mental imagery could induce a multimodal association with postural control. We examined static postural control in the presence of a frequency-modulated sound in three groups of participants, prior to and following a short period of training designed to create an association between auditory mental imagery of sounds and postural swaying. Results suggest that mental imagery impacted performance, as a significant decrease in postural control was observed in the experimental group following mental imagery training. Results of the control groups confirmed that the effect of mental imagery was not due to response bias, but to a significant multimodal interaction following training. These findings are in accordance with previous studies suggesting that mental imagery stimuli can interact with perceptual stimuli of a different sensory modality and lead to multisensory integration. The results also confirm that audiomotor interaction can be generated a mental imagery training. However, the full extent of mental imagery influence on multimodal interaction remains to be determined.

Enhanced vestibulo-ocular reflex suppression in dancers during passive high-velocity head impulses.

The vestibulo-ocular reflex (VOR) is responsible for stabilizing images on the fovea during head movements. However, in some situations, one needs to suppress the VOR to be able to follow a target moving along with the head. Evidence suggests that the visual mechanism underlying VOR suppression can be modulated by experience. Unfortunately, the non-visual mechanism underlying VOR suppression has never been examined in dancers and, consequently, it is still unsure whether dance training can enhance eye-head tracking accuracy. The goal of the present study was to look at the influence of dance training on the VOR suppression during passive head impulses. Twenty-four individuals participated, 12 controls and 12 dancers. VOR and VOR suppression were assessed using a head impulse paradigm as well as a suppression head impulse test paradigm (SHIMP) with video head impulse test, respectively. The results suggest that dancers display a significantly reduced VOR gain during the SHIMP at 60 ms in comparison to controls. Moreover, dancers with more than 10 years of dance training exhibited a significantly reduced VOR gain during the SHIMP at 60 ms. Overall, the results suggest that dance training improves VOR suppression, but also modulates VOR suppression abilities. Although studies are needed to shed light on the possible mechanisms involved in the modulation of the VOR gain, the observed changes in dancers' vestibulo-cerebellum and its role in the modulation of the VOR gain makes the cerebellar-vestibular nuclei pathway a possible model to explain the present results.

Improved tactile frequency discrimination in musicians.

Music practice is a multisensory training that is of great interest to neuroscientists because of its implications for neural plasticity. Music-related modulation of sensory systems has been observed in neuroimaging data, and has been supported by results in behavioral tasks. Some studies have shown that musicians react faster than non-musicians to visual, tactile and auditory stimuli. Behavioral enhancement in more complex tasks has received considerably less attention in musicians. This study aims to investigate unisensory and multisensory discrimination capabilities in musicians. More specifically, the goal of this study is to examine auditory, tactile and auditory-tactile discrimination in musicians. The literature suggesting better auditory and auditory-tactile discrimination in musicians is scarce, and no study to date has examined pure tactile discrimination capabilities in musicians. A two-alternative forced-choice frequency discrimination task was used in this experiment. The task was inspired by musical production, and participants were asked to identify whether a frequency was the same as or different than a standard stimulus of 160 Hz in three conditions: auditory only, auditory-tactile only and tactile only. Three waveforms were used to replicate the variability of pitch that can be found in music. Stimuli were presented through headphones for auditory stimulation and a glove with haptic audio exciters for tactile stimulation. Results suggest that musicians have lower discrimination thresholds than non-musicians for auditory-only and auditory-tactile conditions for all waveforms. The results also revealed that musicians have lower discrimination thresholds than non-musicians in the tactile condition for sine and square waveforms. Taken together, these results support the hypothesis that musical training can lead to better unisensory tactile discrimination which is in itself a new and major finding.

Vestibular Function Modulates the Benefit of Hearing Aids in People With Hearing Loss During Static Postural Control.

OBJECTIVES: To evaluate the influence of auditory cues on postural sway in normal-hearing (NH) individuals, hearing-impaired individuals with vestibular impairment (HIVL), or hearing-impaired (HI) individuals without vestibular impairment. DESIGN: Thirty-two participants received a hearing and a vestibular evaluation (vHIT, oVEMP, cVEMP) and then were separated in to three groups (NH, HI, HIVL). All participants had to stand on a force platform in four postural conditions (A: EO/firm, B: EC/firm, C: EO/Foam, D: EC/Foam) under two auditory conditions, with or without auditory cues. RESULTS: Results revealed that first, there was a significant difference between HIVL and both HI and NH groups in conditions C and D without auditory cues. Second, greater improvement for HIVL compared to NH and HI groups in condition C and D was observed with auditory cues. Finally, somatosensory reliance significantly decreased for the HIVL participants using hearing aids compared to NH and HI. CONCLUSIONS: Our results suggest that hearing aids benefit for postural control may be modulated by vestibular function.

A multi-group approach to examining language development in at-risk learners.

A battery of standardized language tests and control measures was administered to three groups of at-risk language learners - internationally adopted children, deaf children with cochlear implants, and children with specific language impairment - and to groups of second-language learners and typically developing monolingual children. All children were acquiring French, were matched on age, gender, and socioeconomic status, and were between age 5;0 and 7;3 at the time of testing. Differences between the at-risk and not-at-risk groups were evident in all domains of language testing. The children with SLI or CIs scored significantly lower than the IA children and all three at-risk groups scored lower than the monolingual group; the L2 and IA groups scored similarly. The results suggest that children with limited access to, or ability to process, early language input are at greater risk than children with delayed input to an additional language but otherwise typical or relatively typical early input.

Body Perception and Action Following Deafness.

The effect of deafness on sensory abilities has been the topic of extensive investigation over the past decades. These investigations have mostly focused on visual capacities. We are only now starting to investigate how the deaf experience their own bodies and body-related abilities. Indeed, a growing corpus of research suggests that auditory input could play an important role in body-related processing. Deafness could therefore disturb such processes. It has also been suggested that many unexplained daily difficulties experienced by the deaf could be related to deficits in this underexplored field. In the present review, we propose an overview of the current state of knowledge on the effects of deafness on body-related processing.

Delayed auditory experience results in past tense production difficulties and working memory deficits in children with cochlear implants: A comparison with children with developmental language disorder.

Extent evidence has shown that morphosyntax is one of the most challenging linguistic areas for children with atypical early language experiences. Over the last couple of years, comparisons between deaf children with CIs and children with DLD have gained interest - as cases of atypical early language experiences, including, but not restricted to, delayed onset of exposure to language input and language-processing difficulties. Evidence suggests that the morphosyntactic difficulties experienced by deaf children with CIs and children with DLD are very similar in nature. However, the few studies that have directly compared both groups are inconclusive, with deaf children with CIs either performing significantly better or on par with children with DLD. These differences in findings can be attributed, in part at least, to a failure to implement essential methodological controls - even more so given that deaf children with CIs comprise a very diverse population. The goal of the present study was to directly compare the performance of deaf children with CIs to that of children with DLD on a morphosyntactic ability known to be particularly difficult for both groups. Specifically, the present study conducted a detailed examination of the past tense marking abilities of deaf children with CIs and children with DLD while controlling for factors specific to deaf children with CIs, for children's basic cognitive abilities as well as for children's age, sex assigned at birth, and SES. Past tense verbs are particularly relevant as they are used as a marker of developmental language disorder (DLD) in children learning French. Moreover, extent evidence shows that deaf children with CIs and children with DLD have important WM difficulties, but also that there is an association between auditory perception, processing abilities, and working memory (WM) abilities as well as with the acquisition of morphological features, including tense marking. Unfortunately, no study has examined the relation between the accurate production of past tense verbs and WM abilities in children with CIs and children with DLD learning French. Fifteen deaf children with CIs between 5 and 7 years of age were compared to 15 children with DLD and to 15 typically-developing monolingual controls (MON), matched on important variables, using a past tense elicitation task as well as measures of phonological and nonverbal WM abilities. The results confirm that the deaf children with CIs and the children with DLD both performed significantly lower than the MON controls on the past tense elicitation task - suggesting that difficulties with past tense verbs in French might not only be a marker of DLD but, instead, a correlate of atypical language acquisition. Of importance, the present study is the first to show that deaf children with CIs perform significantly lower than children with DLD on a past tense elicitation task - highlighting the importance of using methodological controls. As well, significant correlations were found between the performance of the deaf children with CIs and of the children with DLD on the past tense elicitation task and their phonological and nonverbal WM abilities. Taken together with previous studies conducted in the same populations, this represents another evidence suggesting that early atypical language experiences result in language and WM deficits, including morphosyntactic difficulties.

Hearing Aid Amplification Improves Postural Control for Older Adults With Hearing Loss When Other Sensory Cues Are Impoverished.

Recent studies suggest that sound amplification via hearing aids can improve postural control in adults with hearing impairments. Unfortunately, only a few studies used well-defined posturography measures to assess balance in adults with hearing loss with and without their hearing aids. Of these, only two examined postural control specifically in the elderly with hearing loss. The present study examined the impact of hearing aid use on postural control during various sensory perturbations in older adults with age-related hearing loss. Thirty individuals with age-related hearing impairments and using hearing aids bilaterally were tested. Participants were asked to perform a modified clinical sensory integration in balance test on a force platform with and without hearing aids. The experiment was conducted in the presence of a broadband noise ranging from 0.1 to 4 kHz presented through a loudspeaker. As expected, hearing aid use had a beneficial impact on postural control, but only when visual and somatosensory inputs were both reduced. Data also suggest that hearing aid use decreases the dependence on somatosensory input for maintaining postural control. This finding can be of particular importance in older adults considering the reduction of tactile and proprioceptive sensitivity and acuity often associated with aging. These results provide an additional argument for encouraging early hearing aid fitting for people with hearing loss.

Functional reorganization of the auditory pathways following late callosotomy.

Injuries at various levels of the auditory system have been shown to lead to functional reorganization of the auditory pathways. In particular, it has recently been shown that such reorganization can occur in callosal agenesis. The pattern of cortical activity following callosotomy is however still unknown, but behavioral results suggest that it could be significantly different from that observed in callosal agenesis. We aimed to confirm this hypothesis by investigating fMRI responses to complex sounds presented binaurally and monaurally in a callosotomized patient. In the binaural condition, the callosotomized subject showed patterns of auditory cortical activation that were similar to those of neurologically intact individuals. However, in both monaural conditions, the callosotomized individual showed a significant increase of the asymmetries favoring the contralateral pathways. Such patterns of cortical responses are only partially consistent with the results obtained from callosal agenesis subjects using the exact same procedure. Indeed, the latter show differences compared with normals in both binaural and monaural conditions. These findings provide neurological evidence that callosotomy could lead to distinctive functional reorganization of the human auditory pathways.

Vestibular status: A missing factor in our understanding of brain reorganization in deaf individuals.

The brain of deaf people is definitely not just deaf, and we have to reconsider what we know about the impact of hearing loss on brain development in light of comorbid vestibular impairments.

Influence of dance training on challenging postural control task.

BACKGROUND: Previous studies have shown that dance training affects postural control, particularly during challenging tasks. However, it is still unknown whether dance training also affects the ability to use vestibular, somatosensory, and visual cues, thus leading to postural control differences. OBJECTIVE: The main goal of the present study was to evaluate the influence of dance training on sensory weighting during static postural control. METHOD: The center of pressure of 24 participants was recorded (12 dancers and 12 control non-dancers) using a force platform as well as the modified Clinical Test of Sensory Organization in Balance (mCTISB). RESULTS: The results suggest that dancers perform significantly better than controls in conditions where somatosensory cues are disturbed. Moreover, a significant negative correlation between vestibular frequency band and training intensity was observed, along with, a significant positive correlation between visual frequency band and training intensity. SIGNIFICANCE: This research outlines dancers' increased ability to modulate sensory weighting differently than non-dancers during postural task where somatosensory cues are reduced.

Functional reorganization of the human auditory pathways following hemispherectomy: an fMRI demonstration.

The present study investigated the functional reorganization of ipsilateral and contralateral auditory pathways in hemispherectomized subjects. Functional reorganization was assessed using functional Magnetic Resonance Imaging (fMRI) and stimulation with complex sounds presented binaurally and monaurally. For neurologically intact control subjects, results showed that binaural stimulations evoked balanced activity in both hemispheres while monaural stimulations induced strong contralateral activity and weak ipsilateral activity. The results obtained from hemispherectomized subjects were substantially different from those obtained from control subjects. Specifically, activity in the intact hemisphere showed a significant decrease in response to contralateral stimulation but, concomitantly, an increase in response to ipsilateral stimulation. The present findings suggest that a substantial functional reorganization takes place in the auditory pathways following an early hemispherectomy. The exact nature of this functional reorganization remains to be specified.

Auditory processing in a patient with a unilateral lesion of the inferior colliculus.

The role of the inferior colliculus (IC) in human auditory processing is still poorly understood. We report here the results obtained with a 12-year-old boy (FX) who suffered a very circumscribed lesion of the right IC without additional neurological damage. The child underwent an extensive battery of psychophysical hearing tests. Results revealed normal peripheral auditory functioning, bilaterally. Furthermore, masking-level differences and frequency-pattern recognition were normal for each ear. When the right ear was stimulated, behavioural tests assessing central auditory processing yielded normal results. However, when the left ear was stimulated, speech recognition in the presence of a competing ipsilateral signal and duration-pattern recognition were impaired. Similarly, performance on two dichotic speech recognition tests was poor when the target stimulus was presented in the left and the competing signal in the right ear. Finally, sound-source localization in space was deficient for speakers located on the side contralateral to the lesion. The pattern of results suggests that auditory functions such as recognition of low-redundancy speech presented monaurally, recognition of tone duration patterns, binaural separation and integration, as well as sound-source localization in space, depend on the integrity of the bilateral auditory pathways at the IC level.