In 2001, Ramachandran and Hubbard introduced the cross-activation model of grapheme-colour synaesthesia. On the occasion of its 10-year anniversary, we review the evidence from experiments that have been conducted to test the model to assess how it has fared. We examine data from behavioural, functional magnetic resonance imaging (fMRI), anatomical studies (diffusion tensor imaging and voxel-ba...

This study documents an unusual case of developmental synaesthesia, in which speech sounds induce an involuntary sensation of taste that is subjectively located in the mouth. JIW shows a highly structured, non-random relationship between particular combinations of phonemes (rather than graphemes) and the resultant taste, and this is influenced by a number of fine-grained phonemic properties (e....

Synaesthesia is a developmental condition involving cross-communication between sensory modalities or substreams whereby an inducer (e.g. a sound) automatically evokes a concurrent percept in another modality (e.g. a colour). Whether this condition arises due to atypical structural connectivity (e.g., between normally unconnected cortical areas) or altered neurochemistry remains a central quest...

Although it is estimated that as many as 4% of people experience some form of enhanced cross talk between (or within) the senses, known as synaesthesia, very little is understood about the level of information processing required to induce a synaesthetic experience. In work presented here, we used a well-known multisensory illusion called the McGurk effect to show that synaesthesia is driven by...

BACKGROUND Synaesthesia is a neurological condition which manifests clinically as an involuntary experience of a sensory or cognitive pathway upon stimulation of a second unrelated sensory or cognitive pathway CASE PRESENTATION We report a 55 year old male who presented with a life-long history of grapheme-colour synaesthesia in which the triggering grapheme was the double letter 'll' (a gemi...

In synaesthesia, stimulation of a sensory modality triggers abnormal additional perceptions. Voxel-based morphometry (VBM) was used in 18 grapheme-colour synaesthetes to investigate the neuro-anatomical basis of their abnormal perceptions. More specifically, we tested the hypothesis that in synaesthesia altered connectivity in temporo-occipital and parietal areas may be associated with grey mat...

Automaticity is a defining characteristic of synaesthesia. Here, we assess for automaticity in stimulus-parity synaesthesia; a subtype that has been documented only 3 times in the literature. Synaesthete R experiences many (nonnumerical) stimuli as being odd or even. She described a toy shape-sorter, which paired odd shapes with even colour slots (and vice versa) and relayed difficulties with t...

UNLABELLED SINGLE CASE: DT is a savant with exceptional abilities in numerical memory and mathematical calculations. DT also has an elaborate form of synaesthesia for visually presented digits. Further more, DT also has Asperger syndrome (AS). We carried out two preliminary investigations to establish whether these conditions may contribute to his savant abilities. NEUROIMAGING In an fMRI dig...