Tactile–‘visual’ acuity of the tongue in early blind individuals

This study compares the ‘tactile–visual’ acuity of the tongue for 15 early blind participants with that of 24 age-matched and sex-matched sighted controls. Snellen's tumbling E test was used to assess ‘visual’ acuity using the tongue display unit. The tongue display unit is a sensory substitution device that converts a visual stimulus grabbed by a camera into electro-tactile pulses delivered to the tongue via a grid made out of electrodes. No overall significant difference was found in thresholds between early blind (1/206) and sighted control (1/237) participants. We found, however, a larger proportion of early blind in the two highest visual acuity categories (1/150 and 1/90). These results extend earlier findings that it is possible to measure visual acuity in the blind individuals using the tongue. Moreover, our data demonstrate that a subgroup of early blind participants is more efficient than controls in conveying visual information through the tongue.

[1]  H Summala,et al.  Neural plasticity in processing of sound location by the early blind: an event-related potential study. , 1992, Electroencephalography and clinical neurophysiology.

[2]  M. Ptito,et al.  rTMS of the occipital cortex abolishes Braille reading and repetition priming in blind subjects , 2007, Neurology.

[3]  Paul Bach-y-Rita,et al.  Brain plasticity: ‘visual’ acuity of blind persons via the tongue , 2001, Brain Research.

[4]  A P Rudell,et al.  Transcranial magnetic stimulation in study of the visual pathway. , 1998, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[5]  K O Johnson,et al.  The limit of tactile spatial resolution in humans , 1994, Neurology.

[6]  J. Ponsford.  Tactile spatial resolution in blind Braille readers , 2000, Neurology.

[7]  Frank Rösler,et al.  Lifespan Development and the Brain: Lifespan Development and the Brain , 2006 .

[8]  A. Snyder,et al.  Diffusion tensor imaging reveals white matter reorganization in early blind humans. , 2006, Cerebral cortex.

[9]  R. Malach,et al.  Early ‘visual’ cortex activation correlates with superior verbal memory performance in the blind , 2003, Nature Neuroscience.

[10]  Ingrid M. Kanics,et al.  Tactile Acuity is Enhanced in Blindness , 2003, The Journal of Neuroscience.

[11]  P. Bach-y-Rita,et al.  Sensory substitution and the human–machine interface , 2003, Trends in Cognitive Sciences.

[12]  Norihiro Sadato,et al.  How the Blind “See” Braille: Lessons From Functional Magnetic Resonance Imaging , 2005, The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry.

[13]  A. Volder,et al.  Brain energy metabolism in early blind subjects: neural activity in the visual cortex , 1997, Brain Research.

[14]  Maurice Ptito,et al.  Lifespan Development and the Brain: Sensory Input–Based Adaptation and Brain Architecture , 2006 .

[15]  F. Rösler,et al.  Memory for environmental sounds in sighted, congenitally blind and late blind adults: evidence for cross-modal compensation. , 2003, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

[16]  W. Freeman,et al.  Comparison of visual acuity in macular degeneration patients measured with snellen and early treatment diabetic retinopathy study charts. , 2008, Ophthalmology.

[17]  C. Spence,et al.  Early Vision Impairs Tactile Perception in the Blind , 2004, Current Biology.

[18]  M. Ptito,et al.  Cross-modal plasticity revealed by electrotactile stimulation of the tongue in the congenitally blind. , 2005, Brain : a journal of neurology.

[19]  Albert Gjedde,et al.  Erratum: Transcranial magnetic stimulation of the visual cortex induces somatotopically organized qualia in blind subjects (Proceedings of the National Academy of Sciences of the United States of America (August 29, 2006) 103, 35 (13256-13260) DOI: 10.1073/pnas.0602925103) , 2006 .

[20]  K Sathian,et al.  Visual cortical activity during tactile perception in the sighted and the visually deprived. , 2005, Developmental psychobiology.

[21]  Ron Kupers,et al.  Cross-modal plasticity in early blindness. , 2005, Journal of integrative neuroscience.

[22]  G. Essick,et al.  A letter-recognition task to assess lingual tactile acuity. , 1999, Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons.

[23]  Karl J. Friston,et al.  Early visual deprivation induces structural plasticity in gray and white matter , 2005, Current Biology.

[24]  William M. Stern,et al.  Shape conveyed by visual-to-auditory sensory substitution activates the lateral occipital complex , 2007, Nature Neuroscience.