Cortical activity during tactile exploration of objects in blind and sighted humans

Amedi, Amir; Raz, Noa; Azulay, Haim; Malach, Rafael; Zohary, Ehud

doi:10.3233/rnn-2010-0503

Cited by 94 publications

(87 citation statements)

References 46 publications

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“…Another area well known for its functional specialization is the lateral-occipital complex (LOC), typically involved in object/form recognition processes, which has been shown on several occasions to be responsive to non-visual form processing in EB (Amedi et al, 2007, 2010). Similarly, the visual word form area, which, as its name indicates, responds well to the visual presentation of words, has been shown to be highly responsive to tactually presented Braille words in EB subjects (Reich et al, 2011).…”

Section: Extreme Circumstances: the Case Of Complete Blindnessmentioning

confidence: 99%

“…As discussed earlier, a well documented example of this concerns the LOC, notably involved in object/form recognition processes. Amedi et al (2007, 2010) have shown on multiple occasions that this region is also recruited by auditory and tactile form recognition tasks in EB individuals. Similarly, the visual motion processing center (area MT) has been shown to be recruited by both tactile (Ricciardi et al, 2007) and auditory (Poirier et al, 2006) motion stimuli.…”

Section: Crossmodal Plasticity In Blindness: Bounded By Critical or Smentioning

confidence: 99%

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Sensitive and critical periods in visual sensory deprivation

Voss

2013

Front. Psychol.

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While the demonstration of crossmodal plasticity is well established in congenital and early blind individuals, great debate still surrounds whether those who acquire blindness later in life can also benefit from such compensatory changes. No proper consensus has been reached despite the fact that a proper understanding of the developmental time course of these changes, and whether their occurrence is limited to—or within—specific time windows, is crucial to our understanding of the crossmodal phenomena. An extensive review of the literature reveals that while the majority of investigations to date have examined the crossmodal plasticity available to late blind individuals in quantitative terms, recent findings rather suggest that this reorganization also likely changes qualitatively compared to what is observed in early blindness. This obviously could have significant repercussions not only for the training and rehabilitation of blind individuals, but for the development of appropriate neuroprostheses designed to aid and potentially restore vision. Important parallels will also be drawn with the current state of research on deafness, which is particularly relevant given in the development of successful neuroprostheses (e.g., cochlear implants) for providing auditory input to the central nervous system otherwise aurally deafferented. Lastly, this paper will address important inconsistencies across the literature concerning the definition of distinct blind groups based on the age of blindness onset, and propose several alternatives to using such a categorization.

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Section: Extreme Circumstances: the Case Of Complete Blindnessmentioning

confidence: 99%

Section: Crossmodal Plasticity In Blindness: Bounded By Critical or Smentioning

confidence: 99%

Sensitive and critical periods in visual sensory deprivation

Voss

2013

Front. Psychol.

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“…Cross-modal activations have been described in early and late-blind groups (Amedi et al, 2003, 2010; Buchel et al, 1998; Burton 2003; Cheung et al, 2009; Merabet et al, 2006; Ptito et al, 2005; Sadato et al 1996, 2004; Sathian 2005). However, variability among individuals and correlations between severity of vision loss and amount of cross-modal responses is poorly understood.…”

Section: Introductionmentioning

confidence: 99%

“…However, variability among individuals and correlations between severity of vision loss and amount of cross-modal responses is poorly understood. Tactile discrimination studies of blind have shown increased activation of occipital areas when compared to their sighted counterparts (Amedi et al, 2010; Cheung et al, 2009). Sadato et al (1996) described activation of the primary and secondary visual cortical areas in early-blind subjects during a Braille reading task, and deactivation of those regions in a sighted control group.…”

Section: Introductionmentioning

confidence: 99%

Correlation of vision loss with tactile-evoked V1 responses in retinitis pigmentosa

et al. 2015

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Neuroimaging studies have shown that the visual cortex of visually impaired humans is active during tactile tasks. We sought to determine if this cross-modal activation in the primary visual cortex is correlated with vision loss in individuals with retinitis pigmentosa (RP), an inherited degenerative photoreceptor disease that progressively diminishes vision later in life. RP and sighted subjects completed three tactile tasks: a symmetry discrimination task, a Braille-dot counting task, and a sandpaper roughness discrimination task. We measured tactile-evoked blood oxygenation level dependent (BOLD) responses using functional magnetic resonance imaging (fMRI). For each subject, we quantified the cortical extent of the tactile-evoked response by the proportion of modulated voxels within the primary visual cortex (V1) and its strength by the mean absolute modulation amplitude of the modulated voxels. We characterized vision loss in terms of visual acuity and the areal proportion of V1 that corresponds to the preserved visual field. Visual acuity and proportion of the preserved visual field both had a highly significant effect on the cortical extent of the V1 BOLD response to tactile stimulation, while visual acuity also had a significant effect on the strength of the V1 response. These effects of vision loss on cross-modal responses were reliable despite high inter-subject variability. Controlling for task-evoked responses in the primary somatosensory cortex (S1) across subjects further strengthened the effects of vision loss on cross-model responses in V1. We propose that such cross-modal responses in V1 and other visual areas may be used as a cortically localized biomarker to account for individual differences in visual performance following sight recovery treatments.

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“…Indeed, several groups investigated sensory substitution in blind subjects, trying to re-establish a sensory modality that has been lost by utilizing another one (Bach-y-Rita et al, 1998; Arno et al, 2001; Ptito et al, 2005; Renier et al, 2005; Amedi et al, 2010). These studies show that the blind brain has the ability to meaningfully integrate visual cues delivered in a statistically meaningful way to a different modality like, i.e., audition.…”

Section: Introductionmentioning

confidence: 99%

Sensory Augmentation for the Blind

Kärcher¹,

Fenzlaff²,

Hartmann³

et al. 2012

Front. Hum. Neurosci.

110

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Common navigational aids used by blind travelers during large-scale navigation divert attention away from important cues of the immediate environment (i.e., approaching vehicles). Sensory augmentation devices, relying on principles similar to those at work in sensory substitution, can potentially bypass the bottleneck of attention through sub-cognitive implementation of a set of rules coupling motor actions with sensory stimulation. We provide a late blind subject with a vibrotactile belt that continually signals the direction of magnetic north. The subject completed a set of behavioral tests before and after an extended training period. The tests were complemented by questionnaires and interviews. This newly supplied information improved performance on different time scales. In a pointing task we demonstrate an instant improvement of performance based on the signal provided by the device. Furthermore, the signal was helpful in relevant daily tasks, often complicated for the blind, such as keeping a direction over longer distances or taking shortcuts in familiar environments. A homing task with an additional attentional load demonstrated a significant improvement after training. The subject found the directional information highly expedient for the adjustment of his inner maps of familiar environments and describes an increase in his feeling of security when exploring unfamiliar environments with the belt. The results give evidence for a firm integration of the newly supplied signals into the behavior of this late blind subject with better navigational performance and more courageous behavior in unfamiliar environments. Most importantly, the complementary information provided by the belt lead to a positive emotional impact with enhanced feeling of security. The present experimental approach demonstrates the positive potential of sensory augmentation devices for the help of handicapped people.

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Cortical activity during tactile exploration of objects in blind and sighted humans

Cited by 94 publications

References 46 publications

Sensitive and critical periods in visual sensory deprivation

Sensitive and critical periods in visual sensory deprivation

Correlation of vision loss with tactile-evoked V1 responses in retinitis pigmentosa

Sensory Augmentation for the Blind

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