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

Authors

  • NIKOLAI H JUNG,

    1.  Department of Paediatrics, Technical University Munich, Munich;
    2.  Division of Neuropaediatrics and Muscular Disorders, Department of Paediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg;
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  • WIBKE G JANZARIK,

    1.  Division of Neuropaediatrics and Muscular Disorders, Department of Paediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg;
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  • IGOR DELVENDAHL,

    1.  Division of Neuropaediatrics and Muscular Disorders, Department of Paediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg;
    2.  European Neuroscience Institute Göttingen, Göttingen;
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  • ALEXANDER MÜNCHAU,

    1.  Department of Neurology, University Medical Centre Hamburg-Eppendorf (UKE), Hamburg;
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  • MONICA BISCALDI,

    1.  Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany
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  • FLORIAN MAINBERGER,

    1.  Division of Neuropaediatrics and Muscular Disorders, Department of Paediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg;
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  • TOBIAS BÄUMER,

    1.  Department of Neurology, University Medical Centre Hamburg-Eppendorf (UKE), Hamburg;
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  • REINHOLD RAUH,

    1.  Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany
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  • VOLKER MALL

    1.  Department of Paediatrics, Technical University Munich, Munich;
    2.  Division of Neuropaediatrics and Muscular Disorders, Department of Paediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg;
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Professor Dr Volker Mall at Kinderzentrum München gemeinnützige GmbH, Heiglhofstrasse 63, 81377 München, Germany. E-mail: volker.mall@tum.de

Abstract

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 (PAS25) was performed in patients with HFA/AS (n=9; eight males, one female; mean age 17y 11mo, SD 4y 5mo) and in typically developing age-matched volunteers (n=9; five males, four females; mean age 22y 4mo, SD 5y 2mo). The amplitude of motor-evoked potentials was measured before PAS25, immediately after stimulation, and 30 minutes and 60 minutes later. A PAS protocol adapted to individual N20 latency (PASN20+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 PAS25. 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.

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