title: Touch to see: neuropsychological evidence of a sensory mirror system for touch.
abstract: The observation of touch can be grounded in the activation of brain areas underpinning direct tactile experience, namely the somatosensory cortices. What is the behavioral impact of such a mirror sensory activity on visual perception? To address this issue, we investigated the causal interplay between observed and felt touch in right brain-damaged patients, as a function of their underlying damaged visual and/or tactile modalities. Patients and healthy controls underwent a detection task, comprising visual stimuli depicting touches or without a tactile component. Touch and No-touch stimuli were presented in egocentric or allocentric perspectives. Seeing touches, regardless of the viewing perspective, differently affects visual perception depending on which sensory modality is damaged: In patients with a selective visual deficit, but without any tactile defect, the sight of touch improves the visual impairment; this effect is associated with a lesion to the supramarginal gyrus. In patients with a tactile deficit, but intact visual perception, the sight of touch disrupts visual processing, inducing a visual extinction-like phenomenon. This disruptive effect is associated with the damage of the postcentral gyrus. Hence, a damage to the somatosensory system can lead to a dysfunctional visual processing, and an intact somatosensory processing can aid visual perception.
authors: Department of Psychology, University of Milano-Bicocca, Italy. nadia.bolognini@unimib.it
authors: Nadia
authors: N
authors: Bolognini
authors: Elena
authors: E
authors: Olgiati
authors: Annalisa
authors: A
authors: Xaiz
authors: Lucio
authors: L
authors: Posteraro
authors: Francesco
authors: F
authors: Ferraro
authors: Angelo
authors: A
authors: Maravita
mesh_terms: D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059167:Mirror Neurons / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*