Aims: To study synaesthesia (a “mixing of the senses”) from the perspective of genetics, cognition, and the relationship with autism.
Background: The ARC developed the first diagnostic test for coloured hearing synaesthesia (the Test of Genuineness), conducted the first neuroimaging study of coloured hearing synaesthesia using PET and later MRI, and conducted the first genetic study of coloured hearing synaesthesia. Our work has also shown that synaesthesia is more common in autistic people. This is of particular interest as sensory sensitivity is very common in autistic people. We are working in collaboration with Simon Fisher at the Max Planck Institute for Psycholinguistics in Nijmegen in the Netherlands to identify and characterise genes that may make people more susceptible to developing synaesthesia.
Methods: We have looked at the rate of synaesthesia in autistic people and tested for rare mutations in families where there are several individuals within one family who have synaesthesia.
Results: We found synaesthesia is significantly more common in autistic people than in the general population. We also identified new rare genetic variants or mutations using whole exome sequencing.
Importance: Finding elevated rates of synaesthesia in autistic people suggests the two conditions share some common biological causes at both the neurological level (e.g., over-connectivity) and the genetic level (genes that code for neural over-connectivity).
Relevance: Both autism and synaesthesia are examples of neurodiversity, which illustrates how our genes may change our brain structure and function and consequently our experience.
Funders: The Medical Research Centre; the Autism Research Trust.
- Atypical sensory sensitivity as a shared feature between synaesthesia and autism, Scientific Reports 7:41155 (2017), J. Ward, C Hoadley, J Hughes, P Smith, C Allison, S Baron-Cohen, & J Simner
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