Impaired induction of long-term potentiation-like plasticity in patients with high-functioning autism and Asperger syndrome

Dev Med Child Neurol. 2013 Jan;55(1):83-9. doi: 10.1111/dmcn.12012. Epub 2012 Nov 15.


Aim: We aimed to investigate the induction of long-term potentiation (LTP)-like plasticity by paired associative stimulation (PAS) in patients with high-functioning autism and Asperger syndrome (HFA/AS).

Method: PAS with an interstimulus interval between electrical and transcranial magnetic stimulation of 25 ms (PAS(25)) was performed in patients with HFA/AS (n=9; eight males, one female; mean age 17 y 11 mo, SD 4 y 5 mo) and in typically developing age-matched volunteers (n=9; five males, four females; mean age 22 y 4 mo, SD 5 y 2 mo). The amplitude of motor-evoked potentials was measured before PAS(25), immediately after stimulation, and 30 minutes and 60 minutes later. A PAS protocol adapted to individual N20 latency (PAS(N20+2)) was performed in six additional patients with HFA/AS. Short-interval intracortical inhibition was measured using paired-pulse stimulation.

Results: In contrast to the typically developing participants, the patients with HFA/AS did not show a significant increase in motor-evoked potentials after PAS(25). This finding could also be demonstrated after adaptation for N20 latency. Short-interval intracortical inhibition of patients with HFA/AS was normal compared with the comparison group and did not correlate with PAS effect.

Interpretation: Our results show a significant impairment of LTP-like plasticity induced by PAS in individuals with HFA/AS compared with typically developing participants. This finding is in accordance with results from animal studies as well as human studies. Impaired LTP-like plasticity in patients with HFA/AS points towards reduced excitatory synaptic connectivity and deficits in sensory-motor integration in these patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Asperger Syndrome / pathology*
  • Asperger Syndrome / physiopathology
  • Autistic Disorder / pathology*
  • Autistic Disorder / physiopathology
  • Electric Stimulation
  • Electromyography
  • Evoked Potentials, Motor / physiology*
  • Female
  • Humans
  • Long-Term Potentiation / physiology*
  • Male
  • Motor Cortex / physiopathology*
  • Neural Inhibition / physiology
  • Reaction Time / physiology
  • Time Factors
  • Transcranial Magnetic Stimulation
  • Young Adult