Restorative Neurology and Neuroscience - Volume 28, issue 2

Authors: Röder, Brigitte | Wallace, Mark

Article Type: Other

DOI: 10.3233/RNN-2010-0536

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 141-142, 2010

Authors: Amedi, Amir | Raz, Noa | Azulay, Haim | Malach, Rafael | Zohary, Ehud

Article Type: Research Article

Abstract: Purpose: Recent studies show evidence of multisensory representation in the functionally normal visual cortex, but this idea remains controversial. Occipital cortex activation is often claimed to be a reflection of mental visual imagery processes triggered by other modalities. However, if the occipital cortex is genuinely active during touch, this might be the basis for the massive cross-modal plasticity observed in the congenitally blind. Methods: To address these issues, we used fMRI to compare patterns of …activation evoked by a tactile object recognition (TOR) task (right or left hand) in 8 sighted and 8 congenitally blind subjects, with several other control tasks. Results: TOR robustly activated object selective regions in the lateral occipital complex (LOC/LOtv) in the blind (similar to the patterns of activation found in the sighted), indicating that object identification per se (i.e. in the absence of visual imagery) is sufficient to evoke responses in the LOC/LOtv. Importantly, there was negligible occipital activation for hand movements (imitating object palpations) in the occipital cortex, in both groups. Moreover, in both groups, TOR activation in the LOC/LOtv was bilateral, regardless of the palpating hand (similar to the lack of strong visual field preference in the LOC/LOtv for viewed objects). Finally, the most prominent enhancement in TOR activation in the congenitally blind (compared to their sighted peers) was found in the posterior occipital cortex. Conclusions: These findings suggest that visual imagery is not an obligatory condition for object activation in visual cortex. It also demonstrates the massive plasticity in visual cortex of the blind for tactile object recognition that involves both the ventral and dorsal occipital areas, probably to support the high demand for this function in the blind. Show more

Keywords: Crossmodal plasticity, multisensory processing, neuroimaging, tactile object recognition, visual imagery

DOI: 10.3233/RNN-2010-0503

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 143-156, 2010

Authors: Bergeson, Tonya R. | Houston, Derek M. | Miyamoto, Richard T.

Article Type: Research Article

Abstract: Purpose: Cochlear implantation has recently become available as an intervention strategy for young children with profound hearing impairment. In fact, infants as young as 6 months are now receiving cochlear implants (CIs), and even younger infants are being fitted with hearing aids (HAs). Because early audiovisual experience may be important for normal development of speech perception, it is important to investigate the effects of a period of auditory deprivation and amplification type on multimodal perceptual processes …of infants and children. The purpose of this study was to investigate audiovisual perception skills in normal-hearing (NH) infants and children and deaf infants and children with CIs and HAs of similar chronological ages. Methods: We used an Intermodal Preferential Looking Paradigm to present the same woman's face articulating two words ("judge" and "back") in temporal synchrony on two sides of a TV monitor, along with an auditory presentation of one of the words. Results: The results showed that NH infants and children spontaneously matched auditory and visual information in spoken words; deaf infants and children with HAs did not integrate the audiovisual information; and deaf infants and children with CIs initially did not initially integrate the audiovisual information but gradually matched the auditory and visual information in spoken words. Conclusions: These results suggest that a period of auditory deprivation affects multimodal perceptual processes that may begin to develop normally after several months of auditory experience. Show more

Keywords: Audiovisual speech perception, cochlear implants, hearing aids, hearing loss, infants, children

DOI: 10.3233/RNN-2010-0522

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 157-165, 2010

Authors: Bottari, Davide | Nava, Elena | Ley, Pia | Pavani, Francesco

Article Type: Research Article

Abstract: Purpose: Several studies have reported faster response time to visual stimuli in profoundly deaf individuals. This result is often linked to the processing of peripheral targets, and it is assumed to occur in relation to attention orienting. We evaluated whether enhanced reactivity to visual events in profoundly deaf individuals can be explained by faster orienting of visual attention alone. Methods: We examined 11 deaf individuals and 11 hearing controls, in a simple detection task …and in a shape discrimination task. While simple detection can be performed under distributed attention, shape discrimination requires orienting of spatial attention to the target. The same visual targets served for both tasks, presented at central or peripheral locations and corrected for cortical magnification. Results: The simple detection task revealed faster RTs in deaf than hearing controls, regardless of target location. Moreover, while hearing controls paid a cost in responding to peripheral than central targets, deaf participants performed equally well regardless of target eccentricity. In the shape discrimination task deaf never outperformed hearing controls. Conclusions: These findings reveal that enhanced reactivity to visual stimuli in the deaf cannot be explained only by faster orienting of visual attention and can emerge for central as well as peripheral targets. Moreover, the persisting advantage for peripheral locations in the deaf, observed here under distributed attention, suggests that this spatially-selective effect could result from reorganised sensory processing rather than different attentional gradients. Show more

Keywords: deafness, visual attention, plasticity, multisensory

DOI: 10.3233/RNN-2010-0502

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 167-179, 2010

Authors: Dye, Matthew W. G. | Bavelier, Daphne

Article Type: Research Article

Abstract: The literature on visual attention in deaf individuals presents two competing views. On one hand, the deficit view proposes that auditory input is necessary for the development of visual attention; on the other hand, the compensation view holds that visual attention reorganizes to allow the individual to compensate for the lack of auditory input. While apparently contradictory, we suggest that these views shed complementary light on the cross-modal reorganization of visual attention after early deafness. First, …these two fields of inquiry look at different aspects of attention. The deficit view is mostly supported by studies of allocation of attention in time, whereas the compensation view is backed by studies measuring the allocation of attention across space. Second, they focus on groups of different age and different background. Deficits have been documented mostly in children with mixed hearing loss aetiologies, whereas reorganization has been documented in a less representative, but more homogenous group of Deaf adults. We propose a more integrative view in which early auditory deprivation does not result in better or worse visual attention. Rather, selected aspects of visual attention are modified in various ways along the developmental trajectory as a result of early deafness. Show more

Keywords: deafness, RSVP, spatial attention, attentional blink, temporal segmentation, cross modal plasticity

DOI: 10.3233/RNN-2010-0501

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 181-192, 2010

Authors: Fiehler, Katja | Rösler, Frank

Article Type: Research Article

Abstract: The dorsal stream has been proposed to compute vision for space perception and for the control of action. However, perceiving space and guiding movements is not only based on vision but also on other sensory modalities such as proprioception and kinesthesia. Blind people who lost vision early in life provide an exceptional example to study the plasticity of dorsal stream functions. Using fMRI and psychophysical methods, action control and space perception was investigated in congenitally blind …and sighted adults while performing active and passive hand movements without visual feedback. The functional imaging data showed largely overlapping activation patterns for kinesthetically guided hand movements in congenitally blind and sighted participants covering regions of the dorsal stream. In contrast to the sighted participants, congenitally blind participants additionally activated the extrastriate cortex and the auditory cortex. The psychophysical results revealed a significant correlation between proprioceptive spatial discrimination acuity of the blind and the age when they had attended an orientation and mobility training, i.e., an extensive non-visual spatial training. The earlier the blind acquired such a spatial training the more accurate and the more precise was their space perception in later life. Our findings suggest a multisensory network of movement control that develops on the basis of sensorimotor feedback rather than being under the exclusive control of vision. Thus, visual deprivation seems to result in both cross-modal and compensatory intra-modal plasticity. The present findings further imply that dorsal stream functions are shaped by non-visual spatial information during early development. Show more

Keywords: dorsal stream, kinesthesia, motor control, posterior parietal cortex, proprioception, space perception

DOI: 10.3233/RNN-2010-0500

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 193-205, 2010

Authors: Gilley, Phillip M. | Sharma, Anu | Mitchell, Teresa V. | Dorman, Michael F.

Article Type: Research Article

Abstract: Purpose: Children who experience long periods of auditory deprivation are susceptible to large-scale reorganization of auditory cortical areas responsible for the perception of speech and language. One consequence of this reorganization is that integration of combined auditory and visual information may be altered after hearing is restored with a cochlear implant. Our goal was to investigate the effects of reorganization in a task that examines performance during multisensory integration. Methods: Reaction …times to the detection of basic auditory (A), visual (V), and combined auditory-visual (AV) stimuli were examined in a group of normally hearing children, and in two groups of cochlear implanted children: (1) early implanted children in whom cortical auditory evoked potentials (CAEPs) fell within normal developmental limits, and (2) late implanted children in whom CAEPs were outside of normal developmental limits. Miller's test of the race model inequality was performed for each group in order to examine the effects of auditory deprivation on multisensory integration abilities after implantation. Results: Results revealed a significant violation of the race model inequality in the normally hearing and early implanted children, but not in the group of late implanted children. Conclusion: These results suggest that coactivation to multi-modal sensory input cannot explain the decreased reaction times to multi-modal input in late implanted children. These results are discussed in regards to current models for coactivation to redundant sensory information. Show more

Keywords: Multisensory integration, cochlear implants, redundant signal effect (RSE), race model inequality

DOI: 10.3233/RNN-2010-0525

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 207-218, 2010

Authors: Grossmann, Tobias

Article Type: Research Article

Abstract: Purpose: Interacting with others by reading their emotional expressions is an essential social skill in humans. How this ability develops during infancy and what brain processes underpin infants' perception of emotion in different modalities are the questions dealt with in this paper. Methods: Literature review. Results: The first part provides a systematic review of behavioral findings on infants' developing emotion-reading abilities. The second part presents a set of new electrophysiological studies that …provide insights into the brain processes underlying infants' developing abilities. Throughout, evidence from unimodal (face or voice) and multimodal (face and voice) processing of emotion is considered. The implications of the reviewed findings for our understanding of developmental models of emotion processing are discussed. Conclusions: The reviewed infant data suggest that (a) early in development, emotion enhances the sensory processing of faces and voices, (b) infants' ability to allocate increased attentional resources to negative emotional information develops earlier in the vocal domain than in the facial domain, and (c) at least by the age of 7 months, infants reliably match and recognize emotional information across face and voice. Show more

DOI: 10.3233/RNN-2010-0499

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 219-236, 2010

Authors: Peterson, Nathaniel R. | Pisoni, David B. | Miyamoto, Richard T.

Article Type: Research Article

Abstract: Cochlear implants (CIs) process sounds electronically and then transmit electric stimulation to the cochlea of individuals with sensorineural deafness, restoring some sensation of auditory perception. Many congenitally deaf CI recipients achieve a high degree of accuracy in speech perception and develop near-normal language skills. Post-lingually deafened implant recipients often regain the ability to understand and use spoken language with or without the aid of visual input (i.e. lip reading). However, there is wide variation …in individual outcomes following cochlear implantation, and some CI recipients never develop useable speech and oral language skills. The causes of this enormous variation in outcomes are only partly understood at the present time. The variables most strongly associated with language outcomes are age at implantation and mode of communication in rehabilitation. Thus, some of the more important factors determining success of cochlear implantation are broadly related to neural plasticity that appears to be transiently present in deaf individuals. In this article we review the expected outcomes of cochlear implantation, potential predictors of those outcomes, the basic science regarding critical and sensitive periods, and several new research directions in the field of cochlear implantation. Show more

DOI: 10.3233/RNN-2010-0535

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 237-250, 2010

Authors: Putzar, Lisa | Hötting, Kirsten | Röder, Brigitte

Article Type: Research Article

Abstract: Purpose: The investigation of patients treated for bilateral congenital cataracts allows to study the development of visual and multisensory functions after a period of visual deprivation in early infancy. In the present study, cataract patients were tested for their capability to recognize faces and to integrate auditory and visual speech information. Methods: In Experiment 1, 12 cataract patients were tested with the Benton Facial Recognition Test. In Experiment 2, a McGurk paradigm was used that investigated …audio-visual interaction and lip-reading capabilities. Here, fifteen cataract patients participated and were compared to normally sighted controls and to visually impaired controls. Results: In the Benton Facial Recognition Test, cataract patients' performance was unimpaired when target and test face were identical. By contrast, they performed worse than a normally sighted control group when head orientation and/or lighting conditions of the test faces were changed. In the McGurk paradigm, cataract patients displayed impaired lip-reading abilities and a reduced audio-visual interaction compared to normally sighted controls. The latter deficit prevailed even in a sub-group matched for lip-reading capacities with a normally sighted control sub-group. Conclusion: These results suggest that visual input in early infancy is a prerequisite for a normal development of visual and multisensory functions. Show more

Keywords: Visual deprivation, cataract, face recognition, lip-reading, audio-visual integration

DOI: 10.3233/RNN-2010-0526

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 251-257, 2010

Authors: Royal, David W. | Krueger, Juliane | Fister, Matthew C. | Wallace, Mark T.

Article Type: Research Article

Abstract: Purpose: Previous work has established that the integrative capacity of multisensory neurons in the superior colliculus (SC) matures over a protracted period of postnatal life (Wallace and Stein, 1997), and that the development of normal patterns of multisensory integration depends critically on early sensory experience (Wallace et al., 2004). Although these studies demonstrated the importance of early sensory experience in the creation of mature multisensory circuits, it remains unknown whether the reestablishment of …sensory experience in adulthood can reverse these effects and restore integrative capacity. Methods: The current study tested this hypothesis in cats that were reared in absolute darkness until adulthood and then returned to a normal housing environment for an equivalent period of time. Single unit extracellular recordings targeted multisensory neurons in the deep layers of the SC, and analyses were focused on both conventional measures of multisensory integration and on more recently developed methods designed to characterize spatiotemporal receptive fields (STRF). Results: Analysis of the STRF structure and integrative capacity of multisensory SC neurons revealed significant modifications in the temporal response dynamics of multisensory responses (e.g., discharge durations, peak firing rates, and mean firing rates), as well as significant changes in rates of spontaneous activation and degrees of multisensory integration. Conclusions: These results emphasize the importance of early sensory experience in the establishment of normal multisensory processing architecture and highlight the limited plastic potential of adult multisensory circuits. Show more

Keywords: superior colliculus, multimodal, cat, cross-modal, experiential plasticity

DOI: 10.3233/RNN-2010-0488

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 259-270, 2010

Authors: Sathian, K. | Stilla, Randall

Article Type: Research Article

Abstract: This review focusses on cross-modal plasticity resulting from visual deprivation. This is viewed against the background of task-specific visual cortical recruitment that is routine during tactile tasks in the sighted and that may depend in part on visual imagery. Superior tactile perceptual performance in the blind may be practice-related, although there are unresolved questions regarding the effects of Braille-reading experience and the age of onset of blindness. While visual cortical areas are clearly more involved in …tactile microspatial processing in the blind than in the sighted, it still remains unclear how to reconcile these tactile processes with the growing literature implicating visual cortical activity in a wide range of cognitive tasks in the blind, including those involving language, or with studies of short-term, reversible visual deprivation in the normally sighted that reveal plastic changes even over periods of hours or days. Show more

DOI: 10.3233/RNN-2010-0534

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 271-281, 2010

Authors: Tremblay, Corinne | Champoux, François | Lepore, Franco | Théoret, Hugo

Article Type: Research Article

Abstract: Purpose: Recent studies suggest that cochlear implant (CI) users have a typical, and perhaps improved, ability to fuse congruent multisensory information. The ability to fuse incongruent auditory and visual inputs, however, remains to be fully investigated. Methods: Here, performance on a classical audiovisual task (the McGurk effect) was assessed in seventeen cochlear-implanted, postlingually deaf individuals with varied degrees of auditory competency. Results: In line with previous studies, our results …revealed audiovisual fusion abilities that were within normal limits in CI users compared to normally-hearing (NH) participants. A different pattern of response emerged, however, when participants' responses were analyzed according to the degree of auditory proficiency with the CI. Although proficient CI users (pCI) and NH participants favoured auditory input when multisensory signals were not fused, only the non-proficient CI users (npCI) relied predominantly on visual cues to resolve audiovisual conflict. This pattern was found despite a similar percentage of fused percepts between pCI users, npCI users and NH participants. Conclusion: These data show a remarkable level of similarity between pCI users and NH individuals in the perception of incongruent audiovisual information, suggesting that optimal auditory performance with the CI is associated with normal fusion of conflicting audiovisual input. Show more

Keywords: Multisensory integration, cochlear implant, deadness, McGurk effect

DOI: 10.3233/RNN-2010-0498

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 283-291, 2010