Visual change detection recruits auditory cortices in early deafness

Unraveling the impact of congenital deafness on individual brain organization

Research on brain plasticity, particularly in the context of deafness, consistently emphasizes the reorganization of the auditory cortex. But to what extent do all individuals with deafness show the same level of reorganization? To address this question, we examined the individual differences in functional connectivity (FC) from the deprived auditory cortex. Our findings demonstrate remarkable differentiation between individuals deriving from the absence of shared auditory experiences, resulting in heightened FC variability among deaf individuals, compared to more consistent FC in the hearing group. Notably, connectivity to language regions becomes more diverse across individuals with deafness. This does not stem from delayed language acquisition; it is found in deaf native signers, who are exposed to natural language since birth. However, comparing FC diversity between deaf native signers and deaf delayed signers, who were deprived of language in early development, we show that language experience also impacts individual differences, although to a more moderate extent. Overall, our research points out the intricate interplay between brain plasticity and individual differences, shedding light on the diverse ways reorganization manifests among individuals. It joins findings of increased connectivity diversity in blindness and highlights the importance of considering individual differences in personalized rehabilitation for sensory loss.

Predicting the unpredicted … brain response: A systematic review of the feature-related visual mismatch negativity (vMMN) and the experimental parameters that affect it

In this systematic review and meta-analysis, I consider aspects of experimental design that affect the visual mismatch negativity (vMMN)-an electrophysiological (neural) correlate of prediction error in vision that is typically largest between 150 ms and 300 ms in the event-related potential (ERP) at occipito-parietal regions on the scalp. I compiled data from 145 published studies investigating changes in a single property or feature of visual input. This review provides a concise summary of the vMMN literature on unexpected changes in features of visual input, outlining the most used (according to review) and optimal (following discussion on theoretical and practical implications) parameters of experiments investigating feature deviance for posterity as well as contemporary research. The data compiled was analysed to reveal meaningful relationships between aspects of experimental design and vMMN mean amplitude and peak latency. Results suggest that whether a control for adaptation is used, whether attention is towards vs. away from the stimulus of interest, and stimulus presentation time determines mean amplitude. Whether attention is towards vs. away from the stimulus of interest, the time between the stimulus of interest, deviant probability, and the number of standards separating deviants determines peak latency. There is also some indication that magnitude of deviance affects mean amplitude in studies exploring orientation deviance. This review and its findings elucidate potentially fruitful areas of future research.

Motion-onset visually evoked potentials are amplified in the deaf

The loss of a sensory modality triggers a phenomenon known as cross-modal plasticity, where areas of the brain responsible for the lost sensory modality are reorganized and repurposed to the benefit of the remaining modalities. After perinatal or congenital deafness, superior visual motion detection abilities have been psychophysically identified in both humans and cats, and this advantage has been causally demonstrated to be mediated by reorganized auditory cortex. In our study, we investigated visually evoked potentials (VEPs) in response to motion-onset stimuli of varying speeds in both hearing and perinatally deafened cats under light anesthesia. Although the peak latencies did not differ between the two groups, we observed significantly greater VEP amplitudes in deaf cats, specifically in the P1 component and the signal power of the overall waveform. Through sigmoidal modeling, we identified that the speed offset and steepness at the threshold for 50% maximum neural activity was unchanged, showing that neuronal activity was modulated by motion speeds in a comparable manner between the hearing and deaf subjects and the deaf had greater potentials at all dot speeds. Our results suggest that the increased cortical activity by the auditory and visual cortices of deaf cats may account for their superior behavioral advantage in motion detection and indicates that cross-modal plasticity plays a significant role in the cortical processing of motion. NEW & NOTEWORTHY The present study investigated cross-modal plasticity after perinatal deafness in cats using motion-onset visually evoked potentials. Deaf animals were observed to have significantly greater evoked potentials in both peak components and the signal power of the overall waveforms. These results are discussed in relation to prior studies on deaf subjects in both human and animal research on evoked potentials and psychophysics.

Orienting attention to auditory and visual working memory in older adults with cochlear implants

Cochlear implantation is a well-established method for restoring hearing sensation in individuals with severe to profound hearing loss. It significantly improves verbal communication for many users, despite substantial variability in patients' reports and performance on speech perception tests and quality-of-life outcome measures. Such variability in outcome measures remains several years after implantation and could reflect difficulties in attentional regulation. The current study assessed the ability to use a cue to guide attention internally toward visual or auditory working memory (i.e., reflective attention) in cochlear implant (CI) users. Participants completed a cognitive task called the delayed match-to-sample task in which a visual gradient was presented on a computer screen and a piano tone was presented through speakers simultaneously. A visual cue (i.e., letter A or V) instructed participants to focus attention on the item held in auditory or visual working memory. After a delay following the cue presentation, participants were presented with a probe item and indicated by pressing a button whether it matched the cued item in working memory. CI users and age-matched normal hearing adults showed comparable benefit from having an informative cue relative to an uninformative cue (i.e., letter X). Although CI users have had a history of severe deafness and experience coarse sound information, they were able to retrospectively orient their attention to an item in auditory or visual working memory. These findings suggest that CI users with at least one year of CI experience can successfully regulate attention to a level that is comparable to that of normal hearing individuals.

Cross-Modal Plasticity in Postlingual Hearing Loss Predicts Speech Perception Outcomes After Cochlear Implantation

Background: Sensory loss may lead to intra- and cross-modal cortical reorganization. Previous research showed a significant correlation between the cross-modal contribution of the right auditory cortex to visual evoked potentials (VEP) and speech perception in cochlear implant (CI) users with prelingual hearing loss (HL), but not in those with postlingual HL. The present study aimed to explore the cortical reorganization induced by postlingual HL, particularly in the right temporal region, and how it correlates with speech perception outcome with a CI. Material and Methods: A total of 53 adult participants were divided into two groups according to hearing ability: 35 had normal hearing (NH) (mean age = 62.10 years (±7.48)) and 18 had profound postlingual HL (mean age = 63.78 years (±8.44)). VEPs, using a 29-channel electroencephalogram (EEG) system, were recorded preoperatively in the 18 patients scheduled for cochlear implantation and in 35 NH adults who served as the control group. Amplitudes and latencies of the P100, N100, and P200 components were analyzed across frontal, temporal, and occipital areas and compared between NH and HL subjects using repeated measures ANOVA. For the HL group, speech perception in quiet was assessed at 6 and 12 months of CI use. Results: No difference was found in amplitudes or latencies of the P100, N100, and P200 VEP components between the NH and HL groups. Further analysis using Spearman correlations between preoperative amplitudes and latencies of the P100, N100, and P200 VEP components at the right temporal electrode position T8 and postoperative speech perception showed that the HL group had either significantly higher or significantly lower amplitudes of the P200 component at the right temporal electrode position T8 compared to the NH controls. The HL subgroup with higher amplitudes had better speech perception than the subgroup with lower amplitudes at 6 months and 12 months of CI use. Conclusions: Preoperative evaluation of cortical plasticity can reveal plasticity profiles, which might help to better predict postoperative speech outcomes and adapt the rehabilitation regimen after CI activation. Further research is needed to understand the susceptibility of each component to cross-modal reorganization and their specific contribution to outcome prediction.

Changes in visually and auditory attended audiovisual speech processing in cochlear implant users: A longitudinal ERP study

Limited auditory input, whether caused by hearing loss or by electrical stimulation through a cochlear implant (CI), can be compensated by the remaining senses. Specifically for CI users, previous studies reported not only improved visual skills, but also altered cortical processing of unisensory visual and auditory stimuli. However, in multisensory scenarios, it is still unclear how auditory deprivation (before implantation) and electrical hearing experience (after implantation) affect cortical audiovisual speech processing. Here, we present a prospective longitudinal electroencephalography (EEG) study which systematically examined the deprivation- and CI-induced alterations of cortical processing of audiovisual words by comparing event-related potentials (ERPs) in postlingually deafened CI users before and after implantation (five weeks and six months of CI use). A group of matched normal-hearing (NH) listeners served as controls. The participants performed a word-identification task with congruent and incongruent audiovisual words, focusing their attention on either the visual (lip movement) or the auditory speech signal. This allowed us to study the (top-down) attention effect on the (bottom-up) sensory cortical processing of audiovisual speech. When compared to the NH listeners, the CI candidates (before implantation) and the CI users (after implantation) exhibited enhanced lipreading abilities and an altered cortical response at the N1 latency range (90-150 ms) that was characterized by a decreased theta oscillation power (4-8 Hz) and a smaller amplitude in the auditory cortex. After implantation, however, the auditory-cortex response gradually increased and developed a stronger intra-modal connectivity. Nevertheless, task efficiency and activation in the visual cortex was significantly modulated in both groups by focusing attention on the visual as compared to the auditory speech signal, with the NH listeners additionally showing an attention-dependent decrease in beta oscillation power (13-30 Hz). In sum, these results suggest remarkable deprivation effects on audiovisual speech processing in the auditory cortex, which partially reverse after implantation. Although even experienced CI users still show distinct audiovisual speech processing compared to NH listeners, pronounced effects of (top-down) direction of attention on (bottom-up) audiovisual processing can be observed in both groups. However, NH listeners but not CI users appear to show enhanced allocation of cognitive resources in visually as compared to auditory attended audiovisual speech conditions, which supports our behavioural observations of poorer lipreading abilities and reduced visual influence on audition in NH listeners as compared to CI users.

Cross-modal plasticity in children with cochlear implant: converging evidence from EEG and functional near-infrared spectroscopy

Over the first years of life, the brain undergoes substantial organization in response to environmental stimulation. In a silent world, it may promote vision by (i) recruiting resources from the auditory cortex and (ii) making the visual cortex more efficient. It is unclear when such changes occur and how adaptive they are, questions that children with cochlear implants can help address. Here, we examined 7-18 years old children: 50 had cochlear implants, with delayed or age-appropriate language abilities, and 25 had typical hearing and language. High-density electroencephalography and functional near-infrared spectroscopy were used to evaluate cortical responses to a low-level visual task. Evidence for a 'weaker visual cortex response' and 'less synchronized or less inhibitory activity of auditory association areas' in the implanted children with language delays suggests that cross-modal reorganization can be maladaptive and does not necessarily strengthen the dominant visual sense.

Research of visual attention networks in deaf individuals: a systematic review

The impact of deafness on visual attention has been widely discussed in previous research. It has been noted that deficiencies and strengths of previous research can be attributed to temporal or spatial aspects of attention, as well as variations in development and clinical characteristics. Visual attention is categorized into three networks: orienting (exogenous and endogenous), alerting (phasic and tonic), and executive control. This study aims to contribute new neuroscientific evidence supporting this hypothesis. This paper presents a systematic review of the international literature from the past 15 years focused on visual attention in the deaf population. The final review included 24 articles. The function of the orienting network is found to be enhanced in deaf adults and children, primarily observed in native signers without cochlear implants, while endogenous orienting is observed only in the context of gaze cues in children, with no differences found in adults. Results regarding alerting and executive function vary depending on clinical characteristics and paradigms used. Implications for future research on visual attention in the deaf population are discussed.

Developing cortex is functionally pluripotent: Evidence from blindness

How rigidly does innate architecture constrain function of developing cortex? What is the contribution of early experience? We review insights into these questions from visual cortex function in people born blind. In blindness, occipital cortices are active during auditory and tactile tasks. What 'cross-modal' plasticity tells us about cortical flexibility is debated. On the one hand, visual networks of blind people respond to higher cognitive information, such as sentence grammar, suggesting drastic repurposing. On the other, in line with 'metamodal' accounts, sighted and blind populations show shared domain preferences in ventral occipito-temporal cortex (vOTC), suggesting visual areas switch input modality but perform the same or similar perceptual functions (e.g., face recognition) in blindness. Here we bring these disparate literatures together, reviewing and synthesizing evidence that speaks to whether visual cortices have similar or different functions in blind and sighted people. Together, the evidence suggests that in blindness, visual cortices are incorporated into higher-cognitive (e.g., fronto-parietal) networks, which are a major source long-range input to the visual system. We propose the connectivity-constrained experience-dependent account. Functional development is constrained by innate anatomical connectivity, experience and behavioral needs. Infant cortex is pluripotent, the same anatomical constraints develop into different functional outcomes.

Electrophysiological study of visual processing in children with cochlear implants

Electrophysiological studies of congenitally deaf children and adults have reported atypical visual evoked potentials (VEPs) which have been associated with both behavioral enhancements of visual attention as well as poorer performance and outcomes in tests of spoken language speech processing. This pattern has often been interpreted as a maladaptive consequence of early auditory deprivation, whereby a remapping of auditory cortex by the visual system ultimately reduces resources necessary for optimal rehabilitative outcomes of spoken language acquisition and use. Making use of a novel electrophysiological paradigm, we compare VEPs in children with severe to profound congenital deafness who received a cochlear implant(s) prior to 31 months (n = 28) and typically developing age matched controls (n = 28). We observe amplitude enhancements and in some cases latency differences in occipitally expressed P1 and N1 VEP components in CI-using children as well as an early frontal negativity, N1a. We relate these findings to developmental factors such as chronological age and spoken language understanding. We further evaluate whether VEPs are additionally modulated by auditory stimulation. Collectively, these data provide a means to examine the extent to which atypical VEPs are consistent with prior accounts of maladaptive cross-modal plasticity. Our results support a view that VEP changes reflect alterations to visual-sensory attention and saliency mechanisms rather than a re-mapping of auditory cortex. The present data suggests that early auditory deprivation may have temporally prolonged effects on visual system processing even after activation and use of cochlear implant.

Motor Processing in Children With Cochlear Implants as Assessed by Functional Near-Infrared Spectroscopy

Auditory-motor and visual-motor networks are often coupled in daily activities, such as when listening to music and dancing; but these networks are known to be highly malleable as a function of sensory input. Thus, congenital deafness may modify neural activities within the connections between the motor, auditory, and visual cortices. Here, we investigated whether the cortical responses of children with cochlear implants (CI) to a simple and repetitive motor task would differ from that of children with typical hearing (TH) and we sought to understand whether this response related to their language development. Participants were 75 school-aged children, including 50 with CI (with varying language abilities) and 25 controls with TH. We used functional near-infrared spectroscopy (fNIRS) to record cortical responses over the whole brain, as children squeezed the back triggers of a joystick that vibrated or not with the squeeze. Motor cortex activity was reflected by an increase in oxygenated hemoglobin concentration (HbO) and a decrease in deoxygenated hemoglobin concentration (HbR) in all children, irrespective of their hearing status. Unexpectedly, the visual cortex (supposedly an irrelevant region) was deactivated in this task, particularly for children with CI who had good language skills when compared to those with CI who had language delays. Presence or absence of vibrotactile feedback made no difference in cortical activation. These findings support the potential of fNIRS to examine cognitive functions related to language in children with CI.

Neuroplastic changes in functional wiring in sensory cortices of the congenitally deaf: A network analysis

Congenital sensory deprivation induces significant changes in the structural and functional organisation of the brain. These are well-characterised by cross-modal plasticity, in which deprived cortical areas are recruited to process information from non-affected sensory modalities, as well as by other neuroplastic alterations within regions dedicated to the remaining senses. Here, we analysed visual and auditory networks of congenitally deaf and hearing individuals during different visual tasks to assess changes in network community structure and connectivity patterns due to congenital deafness. In the hearing group, the nodes are clearly divided into three communities (visual, auditory and subcortical), whereas in the deaf group a fourth community consisting mainly of bilateral superior temporal sulcus and temporo-insular regions is present. Perhaps more importantly, the right lateral geniculate body, as well as bilateral thalamus and pulvinar joined the auditory community of the deaf. Moreover, there is stronger connectivity between bilateral thalamic and pulvinar and auditory areas in the deaf group, when compared to the hearing group. No differences were found in the number of connections of these nodes to visual areas. Our findings reveal substantial neuroplastic changes occurring within the auditory and visual networks caused by deafness, emphasising the dynamic nature of the sensory systems in response to congenital deafness. Specifically, these results indicate that in the deaf but not the hearing group, subcortical thalamic nuclei are highly connected to auditory areas during processing of visual information, suggesting that these relay areas may be responsible for rerouting visual information to the auditory cortex under congenital deafness.

Crossmodal plasticity in hearing loss

Crossmodal plasticity is a textbook example of the ability of the brain to reorganize based on use. We review evidence from the auditory system showing that such reorganization has significant limits, is dependent on pre-existing circuitry and top-down interactions, and that extensive reorganization is often absent. We argue that the evidence does not support the hypothesis that crossmodal reorganization is responsible for closing critical periods in deafness, and crossmodal plasticity instead represents a neuronal process that is dynamically adaptable. We evaluate the evidence for crossmodal changes in both developmental and adult-onset deafness, which start as early as mild-moderate hearing loss and show reversibility when hearing is restored. Finally, crossmodal plasticity does not appear to affect the neuronal preconditions for successful hearing restoration. Given its dynamic and versatile nature, we describe how this plasticity can be exploited for improving clinical outcomes after neurosensory restoration.

A comparative study of the attentional blink of facial expression in deaf and hearing children

The rapid serial visual presentation paradigm was used to investigate differences in the attentional blink between deaf children and hearing children in response to facial expressions of fear and disgust. The results showed that: (1) deaf and hearing children had a higher accuracy rate for T1 with disgustful facial expression than T1 with fear facial expression, (2) There was no significant difference in attentional blink between deaf and hearing children, (3) When T2 appeared at Lag6, the response accuracy of T2 in the disgust T1 condition was lower than that in fear T1 condition. However, no significant difference in T2 at Lag2 was found between the two conditions. The results showed that deaf children and those with hearing were more sensitive to facial expressions of disgust, which captured more attentional resources, and the ability of visual attention of deaf children was not weaker than hearing children.

Temporal visual representation elicits early auditory-like responses in hearing but not in deaf individuals

It is evident that the brain is capable of large-scale reorganization following sensory deprivation, but the extent of such reorganization is to date, not clear. The auditory modality is the most accurate to represent temporal information, and deafness is an ideal clinical condition to study the reorganization of temporal representation when the audio signal is not available. Here we show that hearing, but not deaf individuals, show a strong ERP response to visual stimuli in temporal areas during a time-bisection task. This ERP response appears 50-90 ms after the flash and recalls some aspects of the N1 ERP component usually elicited by auditory stimuli. The same ERP is not evident for a visual space-bisection task, suggesting that the early recruitment of temporal cortex is specific for building a highly resolved temporal representation within the visual modality. These findings provide evidence that the lack of auditory input can interfere with typical development of complex visual temporal representations.

Somatosensory processing in deaf and deafblind individuals: How does the brain adapt as a function of sensory and linguistic experience? A critical review

How do deaf and deafblind individuals process touch? This question offers a unique model to understand the prospects and constraints of neural plasticity. Our brain constantly receives and processes signals from the environment and combines them into the most reliable information content. The nervous system adapts its functional and structural organization according to the input, and perceptual processing develops as a function of individual experience. However, there are still many unresolved questions regarding the deciding factors for these changes in deaf and deafblind individuals, and so far, findings are not consistent. To date, most studies have not taken the sensory and linguistic experiences of the included participants into account. As a result, the impact of sensory deprivation vs. language experience on somatosensory processing remains inconclusive. Even less is known about the impact of deafblindness on brain development. The resulting neural adaptations could be even more substantial, but no clear patterns have yet been identified. How do deafblind individuals process sensory input? Studies on deafblindness have mostly focused on single cases or groups of late-blind individuals. Importantly, the language backgrounds of deafblind communities are highly variable and include the usage of tactile languages. So far, this kind of linguistic experience and its consequences have not been considered in studies on basic perceptual functions. Here, we will provide a critical review of the literature, aiming at identifying determinants for neuroplasticity and gaps in our current knowledge of somatosensory processing in deaf and deafblind individuals.

The Effects of Cortical Reorganization and Applications of Functional Near-Infrared Spectroscopy in Deaf People and Cochlear Implant Users

A cochlear implant (CI) is currently the only FDA-approved biomedical device that can restore hearing for the majority of patients with severe-to-profound sensorineural hearing loss (SNHL). While prelingually and postlingually deaf individuals benefit substantially from CI, the outcomes after implantation vary greatly. Numerous studies have attempted to study the variables that affect CI outcomes, including the personal characteristics of CI candidates, environmental variables, and device-related variables. Up to 80% of the results remained unexplainable because all these variables could only roughly predict auditory performance with a CI. Brain structure/function differences after hearing deprivation, that is, cortical reorganization, has gradually attracted the attention of neuroscientists. The cross-modal reorganization in the auditory cortex following deafness is thought to be a key factor in the success of CI. In recent years, the adaptive and maladaptive effects of this reorganization on CI rehabilitation have been argued because the neural mechanisms of how this reorganization impacts CI learning and rehabilitation have not been revealed. Due to the lack of brain processes describing how this plasticity affects CI learning and rehabilitation, the adaptive and deleterious consequences of this reorganization on CI outcomes have recently been the subject of debate. This review describes the evidence for different roles of cross-modal reorganization in CI performance and attempts to explore the possible reasons. Additionally, understanding the core influencing mechanism requires taking into account the cortical changes from deafness to hearing restoration. However, methodological issues have restricted longitudinal research on cortical function in CI. Functional near-infrared spectroscopy (fNIRS) has been increasingly used for the study of brain function and language assessment in CI because of its unique advantages, which are considered to have great potential. Here, we review studies on auditory cortex reorganization in deaf patients and CI recipients, and then we try to illustrate the feasibility of fNIRS as a neuroimaging tool in predicting and assessing speech performance in CI recipients. Here, we review research on the cross-modal reorganization of the auditory cortex in deaf patients and CI recipients and seek to demonstrate the viability of using fNIRS as a neuroimaging technique to predict and evaluate speech function in CI recipients.

Contralateral dominance to speech in the adult auditory cortex immediately after cochlear implantation

Sensory deprivation causes structural and functional changes in the human brain. Cochlear implantation delivers immediate reintroduction of auditory sensory information. Previous reports have indicated that over a year is required for the brain to reestablish canonical cortical processing patterns after the reintroduction of auditory stimulation. We utilized functional near-infrared spectroscopy (fNIRS) to investigate brain activity to natural speech stimuli directly after cochlear implantation. We presented 12 cochlear implant recipients, who each had a minimum of 12 months of auditory deprivation, with unilateral auditory- and visual-speech stimuli. Regardless of the side of implantation, canonical responses were elicited primarily on the contralateral side of stimulation as early as 1 h after device activation. These data indicate that auditory pathway connections are sustained during periods of sensory deprivation in adults, and that typical cortical lateralization is observed immediately following the reintroduction of auditory sensory input.

The timecourse of multisensory speech processing in unilaterally stimulated cochlear implant users revealed by ERPs

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Both normal-hearing (NH) and cochlear implant (CI) users show a clear benefit in multisensory speech processing.

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Group differences in ERP topographies and cortical source activation suggest distinct audiovisual speech processing in CI users when compared to NH listeners.

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Electrical neuroimaging, including topographic and ERP source analysis, provides a suitable tool to study the timecourse of multisensory speech processing in CI users.

A cochlear implant (CI) is an auditory prosthesis which can partially restore the auditory function in patients with severe to profound hearing loss. However, this bionic device provides only limited auditory information, and CI patients may compensate for this limitation by means of a stronger interaction between the auditory and visual system. To better understand the electrophysiological correlates of audiovisual speech perception, the present study used electroencephalography (EEG) and a redundant target paradigm. Postlingually deafened CI users and normal-hearing (NH) listeners were compared in auditory, visual and audiovisual speech conditions. The behavioural results revealed multisensory integration for both groups, as indicated by shortened response times for the audiovisual as compared to the two unisensory conditions. The analysis of the N1 and P2 event-related potentials (ERPs), including topographic and source analyses, confirmed a multisensory effect for both groups and showed a cortical auditory response which was modulated by the simultaneous processing of the visual stimulus. Nevertheless, the CI users in particular revealed a distinct pattern of N1 topography, pointing to a strong visual impact on auditory speech processing. Apart from these condition effects, the results revealed ERP differences between CI users and NH listeners, not only in N1/P2 ERP topographies, but also in the cortical source configuration. When compared to the NH listeners, the CI users showed an additional activation in the visual cortex at N1 latency, which was positively correlated with CI experience, and a delayed auditory-cortex activation with a reversed, rightward functional lateralisation. In sum, our behavioural and ERP findings demonstrate a clear audiovisual benefit for both groups, and a CI-specific alteration in cortical activation at N1 latency when auditory and visual input is combined. These cortical alterations may reflect a compensatory strategy to overcome the limited CI input, which allows the CI users to improve the lip-reading skills and to approximate the behavioural performance of NH listeners in audiovisual speech conditions. Our results are clinically relevant, as they highlight the importance of assessing the CI outcome not only in auditory-only, but also in audiovisual speech conditions.

Distinct multisensory perceptual processes guide enhanced auditory recognition memory in older cochlear implant users

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Congruent audio-visual encoding enhances later auditory processing in the elderly.

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CI users benefit from additional congruent visual information, similar to controls.

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CI users show distinct neurophysiological processes, compared to controls.

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CI users show an earlier modulation of event-related topographies, compared to controls.

In naturalistic situations, sounds are often perceived in conjunction with matching visual impressions. For example, we see and hear the neighbor’s dog barking in the garden. Still, there is a good chance that we recognize the neighbor’s dog even when we only hear it barking, but do not see it behind the fence. Previous studies with normal-hearing (NH) listeners have shown that the audio-visual presentation of a perceptual object (like an animal) increases the probability to recognize this object later on, even if the repeated presentation of this object occurs in a purely auditory condition. In patients with a cochlear implant (CI), however, the electrical hearing of sounds is impoverished, and the ability to recognize perceptual objects in auditory conditions is significantly limited. It is currently not well understood whether CI users – as NH listeners – show a multisensory facilitation for auditory recognition. The present study used event-related potentials (ERPs) and a continuous recognition paradigm with auditory and audio-visual stimuli to test the prediction that CI users show a benefit from audio-visual perception. Indeed, the congruent audio-visual context resulted in an improved recognition ability of objects in an auditory-only condition, both in the NH listeners and the CI users. The ERPs revealed a group-specific pattern of voltage topographies and correlations between these ERP maps and the auditory recognition ability, indicating a different processing of congruent audio-visual stimuli in CI users when compared to NH listeners. Taken together, our results point to distinct cortical processing of naturalistic audio-visual objects in CI users and NH listeners, which however allows both groups to improve the recognition ability of these objects in a purely auditory context. Our findings are of relevance for future clinical research since audio-visual perception might also improve the auditory rehabilitation after cochlear implantation.

Tracking the time course of sign recognition using ERP repetition priming

Repetition priming and event-related potentials (ERPs) were used to investigate the time course of sign recognition in deaf users of American Sign Language. Signers performed a go/no-go semantic categorization task to rare probe signs referring to people; critical target items were repeated and unrelated signs. In Experiment 1, ERPs were time-locked either to the onset of the video or to sign onset within the video; in Experiment 2, the same full videos were clipped so that video and sign onset were aligned (removing transitional movements), and ERPs were time-locked to video/sign onset. All analyses revealed an N400 repetition priming effect (less negativity for repeated than unrelated signs) but differed in the timing and/or duration of the N400 effect. Results from Experiment 1 revealed that repetition priming effects began before sign onset within a video, suggesting that signers are sensitive to linguistic information within the transitional movement to sign onset. The timing and duration of the N400 for clipped videos were more parallel to that observed previously for auditorily presented words and was 200 ms shorter than either time-locking analysis from Experiment 1. We conclude that time-locking to full video onset is optimal when early ERP components or sensitivity to transitional movements are of interest and that time-locking to the onset of clipped videos is optimal for priming studies with fluent signers.

Developmental experiences alter the temporal processing characteristics of the visual cortex: Evidence from deaf and hearing native signers

To date, the extent to which early experience shapes the functional characteristics of neural circuits is still a matter of debate. In the present study, we tested whether congenital deafness and/or the acquisition of a sign language alter the temporal processing characteristics of the visual system. Moreover, we investigated whether, assuming cross-modal plasticity in deaf individuals, the temporal processing characteristics of possibly reorganised auditory areas resemble those of the visual cortex. Steady-state visual evoked potentials (SSVEPs) were recorded in congenitally deaf native signers, hearing native signers, and hearing nonsigners. The luminance of the visual stimuli was periodically modulated at 12, 21, and 40 Hz. For hearing nonsigners, the optimal driving rate was 12 Hz. By contrast, for the group of hearing signers the optimal driving rate was 12 and 21 Hz, whereas for the group of deaf signers the optimal driving rate was 21 Hz. We did not observe evidence for cross-modal recruitment of auditory cortex in the group of deaf signers. These results suggest a higher preferred neural processing rate as a consequence of the acquisition of a sign language.

Reorganization of large-scale brain networks in deaf signing adults: The role of auditory cortex in functional reorganization following deafness

If the brain is deprived of input from one or more senses during development, functional and structural reorganization of the deprived regions takes place. However, little is known about how sensory deprivation affects large-scale brain networks. In the present study, we use data-driven independent component analysis (ICA) to characterize large-scale brain networks in 15 deaf early signers and 24 hearing non-signers based on resting-state functional MRI data. We found differences between the groups in independent components representing the left lateralized control network, the default network, the ventral somatomotor network, and the attention network. In addition, we showed stronger functional connectivity for deaf compared to hearing individuals from the middle and superior temporal cortices to the cingulate cortex, insular cortex, cuneus and precuneus, supramarginal gyrus, supplementary motor area, and cerebellum crus 1, and stronger connectivity for hearing non-signers to hippocampus, middle and superior frontal gyri, pre- and postcentral gyri, and cerebellum crus 8. These results show that deafness induces large-scale network reorganization, with the middle/superior temporal cortex as a central node of plasticity. Cross-modal reorganization may be associated with behavioral adaptations to the environment, including superior ability in some visual functions such as visual working memory and visual attention, in deaf signers.

Cross-modal integration and plasticity in the superior temporal cortex

In congenitally deaf people, temporal regions typically believed to be primarily auditory enhance their response to nonauditory information. The neural mechanisms and functional principles underlying this phenomenon, as well as its impact on auditory recovery after sensory restoration, yet remain debated. In this chapter, we demonstrate that the cross-modal recruitment of temporal regions by visual inputs in congenitally deaf people follows organizational principles known to be present in the hearing brain. We propose that the functional and structural mechanisms allowing optimal convergence of multisensory information in the temporal cortex of hearing people also provide the neural scaffolding for feeding visual or tactile information into the deafened temporal areas. Innate in their nature, such anatomo-functional links between the auditory and other sensory systems would represent the common substrate of both early multisensory integration and expression of selective cross-modal plasticity in the superior temporal cortex.

Reduced flash lag illusion in early deaf individuals

When a brief flash is quickly presented aligned with a moving target, the flash typically appears to lag behind the moving stimulus. This effect is widely known in the literature as a flash-lag illusion (FLI). The flash-lag is an example of a motion-induced position shift. Since auditory deprivation leads to both enhanced visual skills and impaired temporal abilities, both crucial for the perception of the flash-lag effect, here we hypothesized that lack of audition could influence the FLI. 13 early deaf and 18 hearing individuals were tested in a visual FLI paradigm to investigate this hypothesis. As expected, results demonstrated a reduction of the flash-lag effect following early deafness, both in the central and peripheral visual fields. Moreover, only for deaf individuals, there is a positive correlation between the flash-lag effect in the peripheral and central visual field, suggesting that the mechanisms underlying the effect in the center of the visual field expand to the periphery following deafness. Overall, these findings reveal that lack of audition early in life profoundly impacts early visual processing underlying the flash-lag effect.

The Extent of Task Specificity for Visual and Tactile Sequences in the Auditory Cortex of the Deaf and Hard of Hearing

It has been proposed that the auditory cortex in the deaf humans might undergo task-specific reorganization. However, evidence remains scarce as previous experiments used only two very specific tasks (temporal processing and face perception) in visual modality. Here, congenitally deaf/hard of hearing and hearing women and men were enrolled in an fMRI experiment as we sought to fill this evidence gap in two ways. First, we compared activation evoked by a temporal processing task performed in two different modalities, visual and tactile. Second, we contrasted this task with a perceptually similar task that focuses on the spatial dimension. Additional control conditions consisted of passive stimulus observation. In line with the task specificity hypothesis, the auditory cortex in the deaf was activated by temporal processing in both visual and tactile modalities. This effect was selective for temporal processing relative to spatial discrimination. However, spatial processing also led to significant auditory cortex recruitment which, unlike temporal processing, occurred even during passive stimulus observation. We conclude that auditory cortex recruitment in the deaf and hard of hearing might involve interplay between task-selective and pluripotential mechanisms of cross-modal reorganization. Our results open several avenues for the investigation of the full complexity of the cross-modal plasticity phenomenon.SIGNIFICANCE STATEMENT Previous studies suggested that the auditory cortex in the deaf may change input modality (sound to vision) while keeping its function (e.g., rhythm processing). We investigated this hypothesis by asking deaf or hard of hearing and hearing adults to discriminate between temporally and spatially complex sequences in visual and tactile modalities. The results show that such function-specific brain reorganization, as has previously been demonstrated in the visual modality, also occurs for tactile processing. On the other hand, they also show that for some stimuli (spatial) the auditory cortex activates automatically, which is suggestive of a take-over by a different kind of cognitive function. The observed differences in processing of sequences might thus result from an interplay of task-specific and pluripotent plasticity.

Use of Functional Near-Infrared Spectroscopy to Predict and Measure Cochlear Implant Outcomes: A Scoping Review

Outcomes following cochlear implantation vary widely for both adults and children, and behavioral tests are currently relied upon to assess this. However, these behavioral tests rely on subjective judgements that can be unreliable, particularly for infants and young children. The addition of an objective test of outcome following cochlear implantation is therefore desirable. The aim of this scoping review was to comprehensively catalogue the evidence for the potential of functional near infrared spectroscopy (fNIRS) to be used as a tool to objectively predict and measure cochlear implant outcomes. A scoping review of the literature was conducted following the PRISMA extension for scoping review framework. Searches were conducted in the MEDLINE, EMBASE, PubMed, CINAHL, SCOPUS, and Web of Science electronic databases, with a hand search conducted in Google Scholar. Key terms relating to near infrared spectroscopy and cochlear implants were used to identify relevant publications. Eight records met the criteria for inclusion. Seven records reported on adult populations, with five records only including post-lingually deaf individuals and two including both pre- and post-lingually deaf individuals. Studies were either longitudinal or cross-sectional, and all studies compared fNIRS measurements with receptive speech outcomes. This review identified and collated key work in this field. The homogeneity of the populations studied so far identifies key gaps for future research, including the use of fNIRS in infants. By mapping the literature on this important topic, this review contributes knowledge towards the improvement of outcomes following cochlear implantation.

Oscillatory signatures of Repetition Suppression and Novelty Detection reveal altered induced visual responses in early deafness

The ability to differentiate between repeated and novel events represents a fundamental property of the visual system. Neural responses are typically reduced upon stimulus repetition, a phenomenon called Repetition Suppression (RS). On the contrary, following a novel visual stimulus, the neural response is generally enhanced, a phenomenon referred to as Novelty Detection (ND). Here, we aimed to investigate the impact of early deafness on the oscillatory signatures of RS and ND brain responses. To this aim, electrophysiological data were acquired in early deaf and hearing control individuals during processing of repeated and novel visual events unattended by participants. By studying evoked and induced oscillatory brain activities, as well as inter-trial phase coherence, we linked response modulations to feedback and/or feedforward processes. Results revealed selective experience-dependent changes on both RS and ND mechanisms. Compared to hearing controls, early deaf individuals displayed: (i) greater attenuation of the response following stimulus repetition, selectively in the induced theta-band (4-7 Hz); (ii) reduced desynchronization following the onset of novel visual stimuli, in the induced alpha and beta bands (8-12 and 13-25 Hz); (iii) comparable modulation of evoked responses and inter-trial phase coherence. The selectivity of the effects in the induced responses parallels findings observed in the auditory cortex of deaf animal models following intracochlear electric stimulation. The present results support the idea that early deafness alters induced oscillatory activity and the functional tuning of basic visual processing.

Visual representations of time elicit early responses in human temporal cortex

Time perception is inherently part of human life. All human sensory modalities are always involved in the complex task of creating a temporal representation of the external world. However, when representing time, people primarily rely on auditory information. Since the auditory system prevails in many audio-visual temporal tasks, one may expect that the early recruitment of the auditory network is necessary for building a highly resolved and flexible temporal representation in the visual modality. To test this hypothesis, we asked 17 healthy participants to temporally bisect three consecutive flashes while we recorded EEG. We demonstrated that visual stimuli during temporal bisection elicit an early (50-90 ​ms) response of an extended area of the temporal cortex, likely including auditory cortex too. The same activation did not appear during an easier spatial bisection task. These findings suggest that the brain may use auditory representations to deal with complex temporal representation in the visual system.

Enhancement of visual biological motion recognition in early-deaf adults: Functional and behavioral correlates

Deafness leads to brain modifications that are generally associated with a cross-modal activity of the auditory cortex, particularly for visual stimulations. In the present study, we explore the cortical processing of biological motion that conveyed either non-communicative (pantomimes) or communicative (emblems) information, in early-deaf and hearing individuals, using fMRI analyses. Behaviorally, deaf individuals showed an advantage in detecting communicative gestures relative to hearing individuals. Deaf individuals also showed significantly greater activation in the superior temporal cortex (including the planum temporale and primary auditory cortex) than hearing individuals. The activation levels in this region were correlated with deaf individuals’ response times. This study provides neural and behavioral evidence that cross-modal plasticity leads to functional advantages in the processing of biological motion following lifelong auditory deprivation.

Evaluating hearing performance with cochlear implants within the same patient using daily randomization and imaging-based fitting - The ELEPHANT study

Background

Prospective research in the field of cochlear implants is hampered by methodological issues and small sample sizes. The ELEPHANT study presents an alternative clinical trial design with a daily randomized approach evaluating individualized tonotopical fitting of a cochlear implant (CI).

Methods

A single-blinded, daily-randomized clinical trial will be implemented to evaluate a new imaging-based CI mapping strategy. A minimum of 20 participants will be included from the start of the rehabilitation process with a 1-year follow-up period. Based on a post-operative cone beam CT scan (CBCT), mapping of electrical input will be aligned to natural place-pitch arrangement in the individual cochlea. The CI’s frequency allocation table will be adjusted to match the electrical stimulation of frequencies as closely as possible to corresponding acoustic locations in the cochlea. A randomization scheme will be implemented whereby the participant, blinded to the intervention allocation, crosses over between the experimental and standard fitting program on a daily basis, and thus effectively acts as his own control, followed by a period of free choice between both maps to incorporate patient preference. With this new approach the occurrence of a first-order carryover effect and a limited sample size is addressed.

Discussion

The experimental fitting strategy is thought to give rise to a steeper learning curve, result in better performance in challenging listening situations, improve sound quality, better complement residual acoustic hearing in the contralateral ear and be preferred by recipients of a CI. Concurrently, the suitability of the novel trial design will be considered in investigating these hypotheses.

Trial registration

ClinicalTrials.gov: NCT03892941. Registered 27 March 2019.

The Cross-Modal Effects of Sensory Deprivation on Spatial and Temporal Processes in Vision and Audition: A Systematic Review on Behavioral and Neuroimaging Research since 2000

One of the most significant effects of neural plasticity manifests in the case of sensory deprivation when cortical areas that were originally specialized for the functions of the deprived sense take over the processing of another modality. Vision and audition represent two important senses needed to navigate through space and time. Therefore, the current systematic review discusses the cross-modal behavioral and neural consequences of deafness and blindness by focusing on spatial and temporal processing abilities, respectively. In addition, movement processing is evaluated as compiling both spatial and temporal information. We examine whether the sense that is not primarily affected changes in its own properties or in the properties of the deprived modality (i.e., temporal processing as the main specialization of audition and spatial processing as the main specialization of vision). References to the metamodal organization, supramodal functioning, and the revised neural recycling theory are made to address global brain organization and plasticity principles. Generally, according to the reviewed studies, behavioral performance is enhanced in those aspects for which both the deprived and the overtaking senses provide adequate processing resources. Furthermore, the behavioral enhancements observed in the overtaking sense (i.e., vision in the case of deafness and audition in the case of blindness) are clearly limited by the processing resources of the overtaking modality. Thus, the brain regions that were previously recruited during the behavioral performance of the deprived sense now support a similar behavioral performance for the overtaking sense. This finding suggests a more input-unspecific and processing principle-based organization of the brain. Finally, we highlight the importance of controlling for and stating factors that might impact neural plasticity and the need for further research into visual temporal processing in deaf subjects.

What and How the Deaf Brain Sees

Over the past decade, there has been an unprecedented level of interest and progress into understanding visual processing in the brain of the deaf. Specifically, when the brain is deprived of input from one sensory modality (such as hearing), it often compensates with supranormal performance in one or more of the intact sensory systems (such as vision). Recent psychophysical, functional imaging, and reversible deactivation studies have converged to define the specific visual abilities that are enhanced in the deaf, as well as the cortical loci that undergo crossmodal plasticity in the deaf and are responsible for mediating these superior visual functions. Examination of these investigations reveals that central visual functions, such as object and facial discrimination, and peripheral visual functions, such as motion detection, visual localization, visuomotor synchronization, and Vernier acuity (measured in the periphery), are specifically enhanced in the deaf, compared with hearing participants. Furthermore, the cortical loci identified to mediate these functions reside in deaf auditory cortex: BA 41, BA 42, and BA 22, in addition to the rostral area, planum temporale, Te3, and temporal voice area in humans; primary auditory cortex, anterior auditory field, dorsal zone of auditory cortex, auditory field of the anterior ectosylvian sulcus, and posterior auditory field in cats; and primary auditory cortex and anterior auditory field in both ferrets and mice. Overall, the findings from these studies show that crossmodal reorganization in auditory cortex of the deaf is responsible for the superior visual abilities of the deaf.

Spatial Cues Influence Time Estimations in Deaf Individuals

Recent studies have reported a strong interaction between spatial and temporal representation when visual experience is missing: blind people use temporal representation of events to represent spatial metrics. Given the superiority of audition on time perception, we hypothesized that when audition is not available complex temporal representations could be impaired, and spatial representation of events could be used to build temporal metrics. To test this hypothesis, deaf and hearing subjects were tested with a visual temporal task where conflicting and not conflicting spatiotemporal information was delivered. As predicted, we observed a strong deficit of deaf participants when only temporal cues were useful and space was uninformative with respect to time. However, the deficit disappeared when coherent spatiotemporal cues were presented and increased for conflicting spatiotemporal stimuli. These results highlight that spatial cues influence time estimations in deaf participants, suggesting that deaf individuals use spatial information to infer temporal environmental coordinates.

A possible key role of vision in the development of schizophrenia

Based on a brief overview of the various aspects of schizophrenia reported by numerous studies, here we hypothesize that schizophrenia may originate (and in part be performed) from visual areas. In other words, it seems that a normal visual system or at least an evanescent visual perception may be an essential prerequisite for the development of schizophrenia as well as of various types of hallucinations. Our study focuses on auditory and visual hallucinations, as they are the most prominent features of schizophrenic hallucinations (and also the most studied types of hallucinations). Here, we evaluate the possible key role of the visual system in the development of schizophrenia.

Brain Plasticity Can Predict the Cochlear Implant Outcome in Adult-Onset Deafness

Sensory plasticity, which is associated with deafness, has not been as thoroughly investigated in the adult brain as it has in the developing brain. In this study, we examined the brain reorganization induced by auditory deprivation in people with adult-onset deafness and its clinical relevance by measuring glucose metabolism before cochlear implant (CI) surgery. F-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) scans were performed in 37 postlingually deafened patients during the preoperative workup period, and in 39 normal-hearing (NH) controls. Behavioral CI outcomes were measured at 1 year after implantation using a phoneme identification test with auditory cueing only. In the deaf individuals, areas involved in the auditory pathway such as the inferior colliculus and bilateral superior temporal gyri were hypometabolic compared to the NH controls. The hypometabolism observed in the deaf auditory cortices gradually returned to levels similar to the controls as the duration of deafness increased. However, contrary to our previous findings in congenitally deaf children, this metabolic recovery failed to have a significant prognostic value for the recovery of the speech perception ability in adult CI patients. In a broad occipital area centered on the primary visual cortices, glucose metabolism was higher in the deaf patients than the controls, suggesting that the area had become visually hyperactive for sensory compensation immediately after the onset of deafness. In addition, a negative correlation between the metabolic activity and behavioral speech perception outcomes was observed in the visual association areas. In the medial frontal cortices, cortical metabolism in most patients decreased, but patients who had preserved metabolic activities showed better speech performance. These results suggest that the auditory cortex in people with adult-onset deafness is relatively resistant to cross-modal plasticity, and instead, individual traits in late-stage visual processing and cognitive control seem to be more reliable prognostic markers for adult-onset deafness.

Language and Sensory Neural Plasticity in the Superior Temporal Cortex of the Deaf

Visual stimuli are known to activate the auditory cortex of deaf people, presenting evidence of cross-modal plasticity. However, the mechanisms underlying such plasticity are poorly understood. In this functional MRI study, we presented two types of visual stimuli, language stimuli (words, sign language, and lip-reading) and a general stimulus (checkerboard) to investigate neural reorganization in the superior temporal cortex (STC) of deaf subjects and hearing controls. We found that only in the deaf subjects, all visual stimuli activated the STC. The cross-modal activation induced by the checkerboard was mainly due to a sensory component via a feed-forward pathway from the thalamus and primary visual cortex, positively correlated with duration of deafness, indicating a consequence of pure sensory deprivation. In contrast, the STC activity evoked by language stimuli was functionally connected to both the visual cortex and the frontotemporal areas, which were highly correlated with the learning of sign language, suggesting a strong language component via a possible feedback modulation. While the sensory component exhibited specificity to features of a visual stimulus (e.g., selective to the form of words, bodies, or faces) and the language (semantic) component appeared to recruit a common frontotemporal neural network, the two components converged to the STC and caused plasticity with different multivoxel activity patterns. In summary, the present study showed plausible neural pathways for auditory reorganization and correlations of activations of the reorganized cortical areas with developmental factors and provided unique evidence towards the understanding of neural circuits involved in cross-modal plasticity.

Visual cortical activity before and after cochlear implantation: A follow up ERP prospective study in deaf children

ERPs were recorded in response to presentation of static colored patterned stimuli in 25 children (19 to 80months of age at cochlear implantation, CI) with very early prelingual profound deafness (PreLD), 21 postlingual profoundly deaf children (PostLD) (34 to 180months of age at CI) and gender- and age-matched control hearing children. Recording sessions were performed before CI, then 6 and 24months after CI. Results showed that prelingual and, at a lesser degree, postlingual auditory deprivation altered cortical visual neural activity associated to colored shapes from both P1 and N1 cortical processing stages. The P1 and N1 amplitude modifications vanished about 24months after CI in both PreLD and PostLD deaf children. In PreLD the visual processing pattern becomes similar to the typical one essentially by an amplitude decrease of P1 on the left hemisphere together with an amplitude increase of the N1 on the right hemisphere. Finally, in PreLD, increased LH advantage over the RH in N1 amplitude on the cerebellar-occipito-parietal region before CI showed a significant inverse relationship with speech perception outcomes 3years after CI. Investigating early visual processing development and its neural substrates in deaf children would help to understand the variability of CI outcome, because their cortical visual organization diverged from the one of typically developing hearing children, and cannot be predicted from what is observed in deaf adults.

Visually Evoked Visual-Auditory Changes Associated with Auditory Performance in Children with Cochlear Implants

Activation of the auditory cortex by visual stimuli has been reported in deaf children. In cochlear implant (CI) patients, a residual, more intense cortical activation in the frontotemporal areas in response to photo stimuli was found to be positively associated with poor auditory performance. Our study aimed to investigate the mechanism by which visual processing in CI users activates the auditory-associated cortex during the period after cochlear implantation as well as its relation to CI outcomes. Twenty prelingually deaf children with CI were recruited. Ten children were good CI performers (GCP) and ten were poor (PCP). Ten age- and sex- matched normal-hearing children were recruited as controls, and visual evoked potentials (VEPs) were recorded. The characteristics of the right frontotemporal N1 component were analyzed. In the prelingually deaf children, higher N1 amplitude was observed compared to normal controls. While the GCP group showed significant decreases in N1 amplitude, and source analysis showed the most significant decrease in brain activity was observed in the primary visual cortex (PVC), with a downward trend in the primary auditory cortex (PAC) activity, but these did not occur in the PCP group. Meanwhile, higher PVC activation (comparing to controls) before CI use (0M) and a significant decrease in source energy after CI use were found to be related to good CI outcomes. In the GCP group, source energy decreased in the visual-auditory cortex with CI use. However, no significant cerebral hemispheric dominance was found. We supposed that intra- or cross-modal reorganization and higher PVC activation in prelingually deaf children may reflect a stronger potential ability of cortical plasticity. Brain activity evolution appears to be related to CI auditory outcomes.

Multisensory Interference in Early Deaf Adults

Multisensory interactions in deaf cognition are largely unexplored. Unisensory studies suggest that behavioral/neural changes may be more prominent for visual compared to tactile processing in early deaf adults. Here we test whether such an asymmetry results in increased saliency of vision over touch during visuo-tactile interactions. About 23 early deaf and 25 hearing adults performed two consecutive visuo-tactile spatial interference tasks. Participants responded either to the elevation of the tactile target while ignoring a concurrent visual distractor at central or peripheral locations (respond to touch/ignore vision), or they performed the opposite task (respond to vision/ignore touch). Multisensory spatial interference emerged in both tasks for both groups. Crucially, deaf participants showed increased interference compared to hearing adults when they attempted to respond to tactile targets and ignore visual distractors, with enhanced difficulties with ipsilateral visual distractors. Analyses on task-order revealed that in deaf adults, interference of visual distractors on tactile targets was much stronger when this task followed the task in which vision was behaviorally relevant (respond to vision/ignore touch). These novel results suggest that behavioral/neural changes related to early deafness determine enhanced visual dominance during visuo-tactile multisensory conflict.