title: Color synesthesia. Insight into perception, emotion, and consciousness.
abstract: OBJECTIVE
  Synesthesia is an extraordinary perceptual phenomenon, in which individuals experience unusual percepts elicited by the activation of an unrelated sensory modality or by a cognitive process. Emotional reactions are commonly associated. The condition prompted philosophical debates on the nature of perception and impacted the course of art history. It recently generated a considerable interest among neuroscientists, but its clinical significance apparently remains underevaluated. This review focuses on the recent studies regarding variants of color synesthesia, the commonest form of the condition.
  
  
  RESULTS
  Synesthesia is commonly classified as developmental and acquired. Developmental forms predispose to changes in primary sensory processing and cognitive functions, usually with better performances in certain aspects and worse in others, and to heightened creativity. Acquired forms of synesthesia commonly arise from drug ingestion or neurological disorders, including thalamic lesions and sensory deprivation (e.g., blindness). Cerebral exploration using structural and functional imaging has demonstrated distinct patterns in cortical activation and brain connectivity for controls and synesthetes. Artworks of affected painters are most illustrative of the nature of synesthetic experiences.
  
  
  CONCLUSIONS
  Results of the recent investigations on synesthesia offered a remarkable insight into the mechanisms of perception, emotion and consciousness, and deserve attention both from neuroscientists and from clinicians.
authors.affiliation: aSorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, INSERM, U968, CNRS, UMR_7210, Paris, France bDepartment of Clinical Neurosciences, Geneva University School of Medicine, Geneva, Switzerland cNeurology Department, Hôpital Foch, Suresnes, Paris, France.
authors.forename: Avinoam B
authors.initials: AB
authors.lastname: Safran
authors.forename: Nicolae
authors.initials: N
authors.lastname: Sanda
mesh_terms: D003116:Color; D003243:Consciousness / Q000502:physiology*; D004644:Emotions / Q000502:physiology*; D006801:Humans; D010465:Perception / Q000502:physiology*; D010468:Perceptual Disorders / Q000503:physiopathology*; D000080311:Synesthesia