Evidence of Hyperplasticity in adults with Autism Spectrum Disorder

• 1 University of Auckland, School of Psychology, New Zealand 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. Methods: An EEG paradigm for non-invasively eliciting LTP in humans was applied to a group of adults with ASD and matched neurotypical (NT) controls. This paradigm uses high frequency visual stimulation as the LTP inducing stimulus, and the increase in amplitude of the visually-elicited N1b component of the visual evoked potential (VEP) is taken as the index of LTP. Results: It was found that the ASD group had a significantly larger LTP effect relative to the neurotypical control group. Discussion: These results provide support for the “Intense World” theory, in which hyper-plasticity is thought to underlie cognitive symptoms in ASD. This non-invasive paradigm for eliciting LTP has potential to be applied in a clinical setting as a neural marker for ASD.