Visual and spatial modulation of tactile extinction: Behavioural and electrophysiological evidence

Chiara F. Sambo, Giuseppe Vallar, Paola Fortis, Roberta Ronchi, Lucio Posteraro, Bettina Forster, Angelo Maravita

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Crossing the hands over the midline reduces left tactile extinction to double simultaneous stimulation in right-brain-damaged patients, suggesting that spatial attentional biases toward the ipsilesional (right) side of space contribute to the patients' contralesional (left) deficit. We investigated (1) whether the position of the left hand, and its vision, affected processing speed of tactile stimuli, and (2) the electrophysiological underpinnings of the effect of hand position. (1) Four right-brain-damaged patients with spatial neglect and contralesional left tactile extinction or somatosensory deficits, and eight neurologically unimpaired participants, performed a speeded detection task on single taps delivered on their left index finger. In patients, placing the left hand in the right (heteronymous) hemi-space resulted in faster reaction times (RTs) to tactile stimuli, compared to placing that hand in the left (homonymous) hemi-space, particularly when the hand was visible. By contrast, in controls placing the left hand in the heteronymous hemi-space increased RTs. (2) Somatosensory event-related potentials (ERPs) were recorded from one patient and two controls in response to the stimulation of the left hand, placed in the two spatial positions. In the patient, the somatosensory P70, N140, and N250 components were enhanced when the left hand was placed in the heteronymous hemi-space, whereas in controls these components were not modulated by hand position. The novel findings are that in patients placing the left hand in the right, ipsilesional hemi-space yields a temporal advantage in processing tactile stimuli, and this effect may rely on a modulation of stimulus processing taking place as early as in the primary somatosensory cortex, as indexed by evoked potentials. Furthermore, vision enhances tactile processing specifically when the left hand is placed in the hemi-space toward which the patients' attentional biases are pathologically directed, namely rightwards.

Original languageEnglish
JournalFrontiers in Human Neuroscience
Issue numberJULY
DOIs
Publication statusPublished - Jul 25 2012

Fingerprint

Touch
Hand
Evoked Potentials
Reaction Time
Psychological Extinction
Somatosensory Cortex
Brain
Fingers

Keywords

  • Attention
  • ERPs
  • Hand crossing
  • Multisensory
  • Space
  • Tactile extinction

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Neurology
  • Biological Psychiatry
  • Behavioral Neuroscience
  • Neuropsychology and Physiological Psychology

Cite this

Visual and spatial modulation of tactile extinction : Behavioural and electrophysiological evidence. / Sambo, Chiara F.; Vallar, Giuseppe; Fortis, Paola; Ronchi, Roberta; Posteraro, Lucio; Forster, Bettina; Maravita, Angelo.

In: Frontiers in Human Neuroscience, No. JULY, 25.07.2012.

Research output: Contribution to journalArticle

Sambo, Chiara F. ; Vallar, Giuseppe ; Fortis, Paola ; Ronchi, Roberta ; Posteraro, Lucio ; Forster, Bettina ; Maravita, Angelo. / Visual and spatial modulation of tactile extinction : Behavioural and electrophysiological evidence. In: Frontiers in Human Neuroscience. 2012 ; No. JULY.
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