Early visual deprivation affects the development of face recognition and of audio-visual speech perception.
ABSTRACT 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.
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.
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.
These results suggest that visual input in early infancy is a prerequisite for a normal development of visual and multisensory functions.
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ABSTRACT: Several studies conducted in mammals and humans have shown that multisensory processing may be impaired following congenital sensory loss and in particular if no experience is achieved within specific early developmental time windows known as sensitive periods. In this study we investigated whether basic multisensory abilities are impaired in hearing-restored individuals with deafness acquired at different stages of development. To this aim, we tested congenitally and late deaf cochlear implant (CI) recipients, age-matched with two groups of hearing controls, on an audio-tactile redundancy paradigm, in which reaction times to unimodal and crossmodal redundant signals were measured. Our results showed that both congenitally and late deaf CI recipients were able to integrate audio-tactile stimuli, suggesting that congenital and acquired deafness does not prevent the development and recovery of basic multisensory processing. However, we found that congenitally deaf CI recipients had a lower multisensory gain compared to their matched controls, which may be explained by their faster responses to tactile stimuli. We discuss this finding in the context of reorganisation of the sensory systems following sensory loss and the possibility that these changes cannot be "rewired" through auditory reafferentation.PLoS ONE 06/2014; 9(6):e99606. · 3.53 Impact Factor
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ABSTRACT: Amblyopia is a neurodevelopmental disorder of the visual system that is associated with disrupted binocular vision during early childhood. There is evidence that the effects of amblyopia extend beyond the primary visual cortex to regions of the dorsal and ventral extra-striate visual cortex involved in visual integration. Here, we review the current literature on global processing deficits in observers with either strabismic, anisometropic, or deprivation amblyopia. A range of global processing tasks have been used to investigate the extent of the cortical deficit in amblyopia including: global motion perception, global form perception, face perception, and biological motion. These tasks appear to be differentially affected by amblyopia. In general, observers with unilateral amblyopia appear to show deficits for local spatial processing and global tasks that require the segregation of signal from noise. In bilateral cases, the global processing deficits are exaggerated, and appear to extend to specialized perceptual systems such as those involved in face processing.Frontiers in Psychology 06/2014; 5:583. · 2.80 Impact Factor
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ABSTRACT: The ability to use cues from multiple senses in concert is a fundamental aspect of brain function. It maximizes the brain's use of the information available to it at any given moment and enhances the physiological salience of external events. Because each sense conveys a unique perspective of the external world, synthesizing information across senses affords computational benefits that cannot otherwise be achieved. Multisensory integration not only has substantial survival value but can also create unique experiences that emerge when signals from different sensory channels are bound together. However, neurons in a newborn's brain are not capable of multisensory integration, and studies in the midbrain have shown that the development of this process is not predetermined. Rather, its emergence and maturation critically depend on cross-modal experiences that alter the underlying neural circuit in such a way that optimizes multisensory integrative capabilities for the environment in which the animal will function.Nature reviews. Neuroscience 07/2014; 15(8):520-35. · 31.38 Impact Factor