Evidence of hyper-plasticity in adults with Autism Spectrum Disorder

Abstract

Background: Long-term potentiation (LTP) is a form of synaptic plasticity involved in learning and memory. Abnormal levels of LTP have been suggested to contribute to symptoms in a number of disorders, and here we examined the extent to which LTP may be affected in autism spectrum disorders (ASD). While animal models of ASD have suggested LTP may be atypical, the results have been inconsistent in terms of the direction of abnormality. Method: In the present study a paradigm for non-invasively eliciting LTP in humans was utilized to test a group of adults with ASD and matched controls. This paradigm uses high-frequency visual stimulation as the LTP-inducing stimulus, and the effect of LTP is reflected by an increase in amplitude of the visually-elicited N1b component of the visual evoked potential (VEP). Result: Main effects for Hemisphere and Tetanus were found. While Group interactions were not found, a Group by Tetanus interaction was approaching significance and was determined to be weak evidence against the null ((pH0|D = 0.44) therefore, LTP effects were explored within groups for the N1 component. It was found that the ASD group had a greater N1 amplitude compared to controls. Conclusion: Our results showed that the ASD group had greater N1 amplitude post-tetanus over the right hemisphere compared to controls and demonstrate elevated LTP. These results support the notion of enhanced perceptual functioning, as elevated LTP may be related to superior visual processing due to overspecialised neural networks in ASD.