Neural correlates of imagined and synaesthetic colours.

Full Abstract

The experience of colour is a core element of human vision. Colours provide important symbolic and contextual information not conveyed by form alone. Moreover, the experience of colour can arise without external stimulation. For many people, visual memories are rich with colour imagery. In the unusual phenomenon of grapheme-colour synaesthesia, achromatic forms such as letters, words and numbers elicit vivid experiences of colour. Few studies, however, have examined the neural correlates of such internally generated colour experiences. We used functional magnetic resonance imaging (fMRI) to compare patterns of cortical activity for the perception of external coloured stimuli and internally generated colours in a group of grapheme-colour synaesthetes and matched non-synaesthetic controls. In a voluntary colour imagery task, both synaesthetes and non-synaesthetes made colour judgements on objects presented as grey scale photographs. In a synaesthetic colour task, we presented letters that elicited synaesthetic colours, and asked participants to perform a localisation task. We assessed the neural activity underpinning these two different forms of colour experience that occur in the absence of chromatic sensory input. In both synaesthetes and non-synaesthetes, voluntary colour imagery activated the colour-selective area, V4, in the right hemisphere. In contrast, the synaesthetic colour task resulted in unique activity for synaesthetes in the left medial lingual gyrus, an area previously implicated in tasks involving colour knowledge. Our data suggest that internally generated colour experiences recruit brain regions specialised for colour perception, with striking differences between voluntary colour imagery and synaesthetically induced colours.

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Author information

Author/s: Rich, Anina N (AN); Williams, Mark A (MA); Puce, Aina (A); Syngeniotis, Ari (A); Howard, Matthew A (MA); McGlone, Francis (F); Mattingley, Jason B (JB);

Affiliation: Cognitive Neuroscience Laboratory, School of Behavioural Science, University of Melbourne, Victoria 3010, Australia. rich(-atsign-)search.bwh.harvard.edu

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: Neuropsychologia (Neuropsychologia), published in England. (Language: eng)

Reference: 2006-; vol 44 (issue 14) : pp 2918-25

Dates: Created 2006/10/18; Completed 2006/12/12;

PMID: 16901521, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adolescent
Adult
Brain Mapping
Cerebral Cortex - blood supply; physiology
Color
Color Perception - physiology
Female
Humans

Humans
Imagination - physiology
Magnetic Resonance Imaging - methods
Male
Memory - physiology
Pattern Recognition, Visual - physiology
Photic Stimulation - methods
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