Vision in autism spectrum disorders

Autism spectrum disorders (ASDs) are developmental disorders which are thought primarily to affect social functioning. However, there is now a growing body of evidence that unusual sensory processing is at least a concomitant and possibly the cause of many of the behavioural signs and symptoms of ASD. A comprehensive and critical review of the phenomenological, empirical, neuroscientific and theoretical literature pertaining to visual processing in ASD is presented, along with a brief justification of a new theory which may help to explain some of the data, and link it with other current hypotheses about the genetic and neural aetiologies of this enigmatic condition

Neural noise and autism spectrum disorders

A curious aspect of the sensory symptoms of autism spectrum disorders (ASDs), not explained by current neural theories, is the combination of hypersensitivity and hyposensitivity to sensory signals (Baranek et al, 2006 Journal of Child Psychology and Psychiatry 47 591 - 601). Could increased levels of neural noise be the underlying neural symptom of this? Normally the addition of noise to a signal will result in masking, but, if both signal and noise amplitudes are relatively low, stochastic resonance phenomena can amplify the signal, resulting in better-than-expected detectability. The developmental consequences of the presence of this noise from early life provide a neat explanation of many of the social and non-social symptoms of ASDs and their spectrum nature (ie high functioning individuals would have relatively lower levels of neural noise, especially in adulthood). This theory suggests that the best way to examine visual performance in ASDs is to use paradigms based on detecting or discriminating signals in noisy backgrounds. Our preliminary results with such paradigms are encouraging