title: Pre-attentive modulation of brain responses to tones in coloured-hearing synesthetes.
abstract: BACKGROUND
  Coloured-hearing (CH) synesthesia is a perceptual phenomenon in which an acoustic stimulus (the inducer) initiates a concurrent colour perception (the concurrent). Individuals with CH synesthesia "see" colours when hearing tones, words, or music; this specific phenomenon suggesting a close relationship between auditory and visual representations. To date, it is still unknown whether the perception of colours is associated with a modulation of brain functions in the inducing brain area, namely in the auditory-related cortex and associated brain areas. In addition, there is an on-going debate as to whether attention to the inducer is necessarily required for eliciting a visual concurrent, or whether the latter can emerge in a pre-attentive fashion.
  
  
  RESULTS
  By using the EEG technique in the context of a pre-attentive mismatch negativity (MMN) paradigm, we show that the binding of tones and colours in CH synesthetes is associated with increased MMN amplitudes in response to deviant tones supposed to induce novel concurrent colour perceptions. Most notably, the increased MMN amplitudes we revealed in the CH synesthetes were associated with stronger intracerebral current densities originating from the auditory cortex, parietal cortex, and ventral visual areas.
  
  
  CONCLUSIONS
  The automatic binding of tones and colours in CH synesthetes is accompanied by an early pre-attentive process recruiting the auditory cortex, inferior and superior parietal lobules, as well as ventral occipital areas.
authors.affiliation: Division Neuropsychology, Institute of Psychology, University of Zurich, Zurich, Switzerland. l.jaencke@psychologie.uzh.ch
authors.forename: Lutz
authors.initials: L
authors.lastname: Jäncke
authors.forename: Lars
authors.initials: L
authors.lastname: Rogenmoser
authors.forename: Martin
authors.initials: M
authors.lastname: Meyer
authors.forename: Stefan
authors.initials: S
authors.lastname: Elmer
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001288:Attention / Q000502:physiology*; D001303:Auditory Cortex / Q000503:physiopathology; D001307:Auditory Perception / Q000502:physiology*; D058256:Brain Waves / Q000502:physiology*; D016022:Case-Control Studies; D003118:Color Perception / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D010296:Parietal Lobe / Q000503:physiopathology; D010468:Perceptual Disorders / Q000503:physiopathology*; D000080311:Synesthesia; D014793:Visual Cortex / Q000503:physiopathology