***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Several studies have demonstrated enhanced auditory processing in the blind , suggesting that they compensate their visual impairment in part with greater sensitivity of the other senses . However , several physiological studies show that early visual deprivation can impact negatively on auditory spatial localization . Here we report for the first time severely impaired auditory localization in the congenitally blind :  thresholds for spatially bisecting three consecutive , spatially-distributed sound sources were seriously compromised , on average 4.2-fold typical thresholds , and half performing at r and om . In agreement with previous studies , these subjects showed no deficits on simpler auditory spatial tasks or with auditory temporal bisection , suggesting that the encoding of Euclidean auditory relationships is specifically compromised in the congenitally blind . It points to the importance of visual experience in the construction and calibration of auditory spatial maps , with implication s for rehabilitation strategies for the congenitally blind We compared normally hearing individuals and congenitally deaf individuals as they monitored moving stimuli either in the periphery or in the center of the visual field . When participants monitored the peripheral visual field , greater recruitment ( as measured by functional magnetic resonance imaging ) of the motion-selective area MT/MST was observed in deaf than in hearing individuals , whereas the two groups were comparable when attending to the central visual field . This finding indicates an enhancement of visual attention to peripheral visual space in deaf individuals .  Structural equation modeling was used to further characterize the nature of this plastic change in the deaf . The effective connectivity between MT/MST and the posterior parietal cortex was stronger in deaf than in hearing individuals during peripheral but not central attention . Thus , enhanced peripheral attention to moving stimuli in the deaf may be mediated by alterations of the connectivity between MT/MST and the parietal cortex , one of the primary centers for spatial representation and attention An important issue in neuroscience is the effect of visual loss on the remaining senses . Two opposing views have been advanced . On the one h and , visual loss may lead to compensatory plasticity and sharpening of the remaining senses . On the other h and , early blindness may also prevent remaining sensory modalities from a full development . In the case of sound localization , it has been reported recently that , under certain conditions , early-blind humans can localize sounds better than sighted controls . However , these studies were confined to a single sound source in the horizontal plane . This study compares  sound localization  of  early-blind and sighted subjects  in both the horizontal and vertical domain , whereas background noise was added to test more complex hearing conditions . The data show that for high signal-to-noise ( S/N ) ratios , localization by blind and sighted subjects is similar for both azimuth and elevation . At decreasing S/N ratios , the accuracy of the elevation response components deteriorated earlier than the accuracy of the azimuth component in both subject groups . However , although azimuth performance was identical for the two groups , elevation accuracy deteriorated much earlier in the blind subject group . These results indicate that auditory hypercompensation in early-blind humans does not extend to the frontal target domain , where the potential benefit of vision is maximal . Moreover , the results demonstrate for the first time that in this domain the human auditory system may require vision to optimally calibrate the elevation-related spectral pinna cues . Sensitivity to azimuth-encoding binaural difference cues , however , may be adequately calibrated in the absence of vision Evidence from functional neuroimaging studies suggests that the auditory cortex can become more responsive to visual and somatosensory stimulation following deafness , and that this occurs predominately in the right hemisphere . Extensive cross-modal plasticity in prospect i ve cochlear implant recipients is correlated with poor speech outcomes following implantation , highlighting the potential impact of central auditory plasticity on subsequent aural rehabilitation . Conversely , the effects of hearing restoration with a cochlear implant on cortical plasticity are less well understood , since the use of most neuroimaging techniques in CI recipients is either unsafe or problematic due to the electromagnetic artefacts generated by CI stimulation . Additionally , techniques such as functional magnetic resonance imaging ( fMRI ) are confounded by acoustic noise produced by the scanner that will be perceived more by hearing than by deaf individuals . Subsequently it is conceivable that auditory responses to acoustic noise produced by the MR scanner may mask auditory cortical responses to non-auditory stimulation , and render inter-group comparisons less significant . Uniquely , functional near-infrared spectroscopy ( fNIRS ) is a silent neuroimaging technique that is non-invasive and completely unaffected by the presence of a CI . Here , we used fNIRS to study temporal-lobe responses to auditory , visual and somatosensory stimuli in thirty profoundly-deaf participants and thirty normally-hearing controls . Compared with silence , acoustic noise stimuli elicited a significant group fNIRS response in the temporal region of normally-hearing individuals , which was not seen in profoundly-deaf participants . Visual motion elicited a larger group response within the right temporal lobe of profoundly-deaf participants , compared with normally-hearing controls . However , bilateral temporal lobe fNIRS activation to somatosensory stimulation was comparable in both groups . Using fNIRS these results confirm that auditory deprivation is associated with cross-modal plasticity of visual inputs to auditory cortex . Although we found no evidence for plasticity of somatosensory inputs , it is possible that our recordings may have included activation of somatosensory cortex that masked any group differences in auditory cortical responses due to the limited spatial resolution associated with fNIRS Several studies have reported that the early-blind displays higher auditory spatial abilities than the sighted . Although many studies have attempted to delineate the cortical structures that undergo functional reorganization in blind people , few have tried to determine which auditory or non-auditory processes mediate these increased auditory spatial abilities . The aim of this paper is to investigate the role of eye movements and orientation of attention in auditory localization in blind humans . Although we found , in a first experiment , that the influence of eye movements on auditory spatial localization is preserved in spite of congenital visual deprivation , the saccade influence on spatial hearing is not more pronounced in the blind than in the sighted . In a second experiment , early-blind and sighted subjects undertook a task involving discrimination of sound elevation in which auditory targets followed uninformative auditory cues on either side with an intermediate elevation . When sounds were emitted from the frontal hemifield , both groups showed similar auditory localization performance . Although the auditory cue did not affect discrimination accuracy in both groups , early-blind subjects exhibited shorter reaction times than sighted subjects when sound sources were placed at far-lateral locations . Attentional cues , however , had similar effects on both groups of subjects , suggesting that improved auditory spatial abilities are not mediated by attention orienting mechanisms In a series of three experiments , we tested whether deaf native signers process motion velocity information differently from hearing nonsigners . In Experiment 1 , participants watched radially moving dots and were asked to detect the quadrant in which the velocity of the dots had changed . Similar 79 % thresholds were observed in the two population s. In Experiments 2 and 3 , peripheral and central thresholds were assessed separately as previous studies suggest early deafness leads mainly to changes in the processing of visual peripheral information . Neither condition produced an overall population difference . These negative results were not due to a lack of sensitivity in our experiments . Indeed , as has been previously reported , deaf native signers exhibited better thresholds in the right than in the left visual field , whereas the opposite pattern was observed in the hearing . This effect appears triggered by experience with American Sign Language ( ASL ) rather than deafness per se . Overall , this study confirms that early deafness does not enhance motion processing , and suggests that most of the changes previously described in the literature are instead attributable to changes in attention , and possibly special alterations of attention-to-motion processes Previous neuroimaging studies devoted to auditory motion processing have shown the involvement of a cerebral network encompassing the temporoparietal and premotor areas . Most of these studies were based on a comparison between moving stimuli and static stimuli placed at a single location . However , moving stimuli vary in spatial location , and therefore motion detection can include both spatial localisation and motion processing . In this study , we used fMRI to compare neural processing of moving sounds and static sounds in various spatial locations in blindfolded sighted subjects . The task consisted of simultaneously determining both the  nature of a sound stimulus ( pure tone or complex sound ) and the presence or absence of its movement .  When movement was present , subjects had to identify its direction . This comparison of how moving and static stimuli are processed showed the involvement of the parietal lobules , the dorsal and ventral premotor cortex and the planum temporale during auditory motion processing . It also showed the specific recruitment of V5 , the visual motion area . These results suggest that the previously proposed network of auditory motion processing is distinct from the network of auditory localisation . In addition , they suggest that the occipital cortex can process non-visual stimuli and that V5 is not restricted to visual processing It is widely held that early-blind people compensate their visual loss by a general sharpening of spatial hearing . The present study reports a possible exception to this view : when the vertical position ( elevation ) of a sound source had to be localized , four out of six early-blind subjects exhibited systematic deviations in pointing , while two early-blind subjects were as accurate as sighted controls . On the other h and , blind and sighted individuals were able to judge relative positions of different sound locations with similar precision . These results suggest that visual experience may be used to accurately calibrate the relation between the vertical coordinates of auditory space and body , but is not needed to develop sufficiently high resolution of spatial hearing Studies using fMRI have demonstrated that visual stimuli activate auditory cortex in deaf subjects . Given the low temporal resolution of fMRI , it is uncertain whether this activation is associated with initial stimulus processing . Here , we used MEG in deaf and hearing subjects to evaluate whether auditory cortex , devoid of its normal input , comes to serve the visual modality early in the course of stimulus processing . In line with previous findings , visual activity was observed in the auditory cortex of deaf , but not hearing , subjects . This activity occurred within 100–400 ms of stimulus presentation and was primarily over the right hemisphere . These results add to the mounting evidence that removal of one sensory modality in humans leads to neural reorganization of the remaining modalities This functional magnetic resonance imaging study investigated the impact of early auditory deprivation and /or use of a visuospatial language [ American sign language ( ASL ) ] on the organization of neural systems important in visual motion processing by comparing hearing controls with deaf and hearing native signers . Participants monitored moving flowfields under different conditions of spatial and featural attention . Recruitment of the motion-selective area MT – MST in hearing controls was observed to be greater when attention was directed central ly and when the task was to detect motion features , confirming previous reports that the motion network is selectively modulated by different aspects of attention . More importantly , we observed marked differences in the recruitment of motion-related areas as a function of early experience . First , the lateralization of MT – MST was found to shift toward the left hemisphere in early signers , suggesting that early exposure to ASL leads to a greater reliance on the left MT – MST . Second , whereas the two hearing population s displayed more MT – MST activation under central than peripheral attention , the opposite pattern was observed in deaf signers , indicating enhanced recruitment of MT – MST during peripheral attention after early deafness . Third , deaf signers , but neither of the hearing population s , displayed increased activation of the posterior parietal cortex , supporting the view that parietal functions are modified after early auditory deprivation . Finally , only in deaf signers did attention to motion result in enhanced recruitment of the posterior superior temporal sulcus , establishing for the first time in humans that this polymodal area is modified after early sensory deprivation . Together these results highlight the functional and regional specificity of neuroplasticity in humans Early-onset blindness ( EB ) produces measurable advantages in auditory perception , attention , memory and language . Neville and Bavelier [ Neville , H. J. , & Bavelier , D. ( 2001 ) Variability of developmental plasticity . In J. L. McClell and , R. S. Siegler ( Eds . ) Mechanisms of cognitive development : Behavioral and ellon symposia on cognition ( pp . 271 - 301 ) ] hypothesized that faster temporal processing underlies many auditory compensatory effects in the blind . We tested this hypothesis by comparing early-onset blind individuals and sighted counterparts ( SC ) by assessing their rates of perceptual consolidation , the accurate perceptual representation of auditory stimuli . Firstly , we first tested both groups on a  temporal-order judgment task ( TOJ ) .  EB subjects had significantly lower TOJ thresholds than the SC subjects . Secondly , we assessed perceptual consolidation speed using auditory backward masking tasks , taking into account individual TOJ thresholds . Discrimination performance was unaffected at all mask delays in the EB group while the SC subjects needed a mask delay of 160 ms to perform comparably . A backward masking task using single tone stimuli found no differences between the EB and SC groups any mask delay . A simultaneous masking task demonstrated that the mask effectively impaired discrimination in EB subjects at sensory stages . These results suggest that advantages in perceptual consolidation may reflect a mechanism responsible for the short response times and better performance reported in early blind individuals across a number of complex auditory tasks Many studies have reported that blind people compensate for their visual deficit by sharpening auditory processes . Here we compare the sensitivity to echo cues between blind and sighted subjects . In the first experiment , the blind subjects were more accurate than the sighted subjects in localizing an object on the basis of echo cues . To ensure that enhanced echolocalization abilities were not only due to the fact that blind individuals are more used to consciously paying attention to echo cues and are more familiar with this kind of tasks than sighted subjects , we tested both groups of subjects in a simple azimuthal localization task of auditory stimuli . In this second experiment , we evaluated the influence of irrelevant echo signals on auditory localization by placing the subjects and the sound sources at different positions in a sound reverberant room . Results revealed that blind subjects exhibit a higher sensitivity to echo signals than sighted subjects Cross-modal pl 
    Output:
    
Generally , according to the review ed studies , behavioral performance is enhanced in those aspects for which both the deprived and the overtaking senses provide adequate processing re sources .
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 re sources 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 .