Cross-modal plasticity for sensory and motor activation patterns in blind subjects

Performance of blind and sighted humans on a tactile grating detection task

“…Like the tactile acuity enhancement reported in the present study, this recruitment of normally visual cortical areas for tactile processing in blind persons is apparently triggered by the loss of sight itself (see, e.g., Sadato, Okada, Kubota, & Yonekura, 2004). Many of the same occipital cortical areas that in sighted persons subserve vision activate when blind persons perform tactile discrimination tasks (see Gizewski et al, 2003), presumably because modulatory tactile inputs to these occipital areas (see Amedi, Malach, Hendler, Peled, & Zohary, 2001;Macaluso, Frith, & Driver, 2002) strengthen upon loss of competing visual inputs (see Wittenberg, Werhahn, Wassermann, Herscovitch, & Cohen, 2004). Blind persons may have enhanced tactile acuity because they are able to utilize these normally visual areas, in addition to the conventional somatosensory areas, for tactile processing (Cohen et al, 1997).…”

“…Crossmodal plasticity, unlike somatosensory cortical plasticity, occurs in blind subjects who have not learned to read Braille (see, e.g., Sadato et al, 2004) as well as in Braille readers (see, e.g., Burton et al, 2002;Gizewski et al, 2003;Sadato et al, 1998). Furthermore, crossmodal plasticity occurs not only in early blind persons (see, e.g., Gizewski et al, 2003;Sadato et al, 1998), but alsoless extensively, according to several studies (Cohen et al, 1999;Sadato, Okada, Honda, & Yonekura, 2002;Wittenberg et al, 2004)-in those who became blind as adults (see, e.g., Büchel, Price, Frackowiak, & Friston, 1998; Burton et al, 2002;Sadato et al, 2004), and even in sighted adults blindfolded for 5 consecutive days (see Pascual-Leone & Hamilton, 2001).…”

Transcranial magnetic stimulation of the visual cortex induces somatotopically organized qualia in blind subjects

“…This difference implies that, after early visual deprivation, tactile information reaches the visual cortex. This claim is largely supported by results of brain-imaging studies showing activation of the visual cortex in EB subjects during Braille reading (12)(13)(14)(15) and other forms of tactile stimulation (17,36). The importance of deprivation early in life is further underscored by the observation that brain-activity patterns in the occipital cortex evoked by tactile stimulation are significantly stronger in EB compared with LB subjects (14,37).…”

“…For example, the auditory cortices of deaf subjects are activated by (visual) sign language (11). Furthermore, Braille reading by blind subjects proficient in Braille activates their visual cortices (12)(13)(14)(15). The role of the visual cortex in cross-modal plasticity was further substantiated by results of transcranial magnetic stimulation (TMS) studies showing that functional blockade of the rewired cortex interferes with task performance (16).…”

New Treatment Strategies in Diabetic Neuropathy

“…The most well known example is in blind persons where an improved sensory function is noticed. It has also been shown that when a blind person reads Braille activation in the occipital lobe occurs implying that the somatosensory stimuli from reading activates the cortical area responsible for vision (Gizewski et al, 2003). Another example is persons in whom the lack of sensibility can be substituted with hearing.…”