When seeing is feeling: Acquired synaesthesia or phantom touch?

Abstract We report the case of a man (DN) who suffered a right hemisphere stroke which resulted In left hemiparesis, and in a dense left hemisensory loss when he was tested without visual feedback. By contrast, when DN saw and ‘believed’ that he was being touched, he invariably reported that he felt the appropriate tactile sensation. In this latter condition, DN could reliably estimate the pressure with which light touch was applied to his left hand. Furthermore, there was reliable transfer of tactile sensation from the left to the right hand without conscious awareness of touch on the left. Some of these findings are akin to previous reports of acquired synaesthesia; one dissimilarity is that in both developmental and acquired synaesthesia the relationship between the perceptual content experienced in the two modalities is arbitrary. An alternative Interpretation of DN's performance is that it is determined by the output of bimodal visual-somatosensory cells that have been partially deprived of their som...

[1]  M. Raichle,et al.  Blood flow changes in human somatosensory cortex during anticipated stimulation , 1995, Nature.

[2]  S. Aglioti,et al.  Sensory and spatial components of somaesthetic deficits following right brain damage , 1995, Neurology.

[3]  Y Rossetti,et al.  Implicit processing of somaesthetic information: a dissociation between where and how? , 1995, Neuroreport.

[4]  Richard S. J. Frackowiak,et al.  Modulation of conscious experience by peripheral sensory stimuli , 1995, Nature.

[5]  J. Gibson,et al.  Adaptation, after-effect and contrast in the perception of curved lines. , 1933 .

[6]  M Mishkin,et al.  Agnosia, alexia and a remarkable form of amnesia in an adolescent boy. , 1994, Brain : a journal of neurology.

[7]  R. Dejong,et al.  THE NEUROLOGIC EXAMINATION , 1959 .

[8]  J C Craig,et al.  Interference in localizing tactile stimuli , 1989, Perception & psychophysics.

[9]  R. Sterzi,et al.  Exploring somatosensory hemineglect by vestibular stimulation. , 1993, Brain : a journal of neurology.

[10]  T. Brochier,et al.  Covert Processing of Information in Hemianesthesia: A Case Report , 1994, Cortex.

[11]  I ROCK,et al.  Vision and Touch: An Experimentally Created Conflict between the Two Senses , 1964, Science.

[12]  M. Hallett,et al.  Activation of the primary visual cortex by Braille reading in blind subjects , 1996, Nature.

[13]  C. Maitland,et al.  Auditory-visual synesthesia. Report of a case with intact visual pathways. , 1984, Archives of neurology.

[14]  J. Honoré,et al.  Effects of spatially oriented attention on the facilitation of the H reflex by a cutaneous stimulus. , 1983, Electroencephalography and clinical neurophysiology.

[15]  C. Gross,et al.  Coding of visual space by premotor neurons. , 1994, Science.

[16]  S Baron-Cohen,et al.  The physiology of coloured hearing. A PET activation study of colour-word synaesthesia. , 1995, Brain : a journal of neurology.

[17]  C. Gross,et al.  The representation of extrapersonal space: A possible role for bimodal, visual-tactile neurons , 1995 .

[18]  J. Harrison,et al.  Synaesthesia: An Account of Coloured Hearing , 1994 .

[19]  E. Bizzi,et al.  The Cognitive Neurosciences , 1996 .

[20]  Barbara A. Wilson,et al.  The behavioural assessment of visual neglect , 1991 .

[21]  I. Rock.  The Logic of Perception , 1983 .

[22]  Stephen M. Kosslyn,et al.  When does “no” really mean “yes”? A case study in unilateral visual neglect , 1994, Neuropsychologia.

[23]  N. Block.  On a confusion about a function of consciousness , 1995, Behavioral and Brain Sciences.

[24]  F Michel,et al.  Localization without content. A tactile analogue of 'blind sight'. , 1983, Archives of neurology.

[25]  H. Head.  SENSATION AND THE CEREBRAL CORTEX , 1918 .

[26]  H. Pick,et al.  Visual capture produced by prism spectacles , 1965 .