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document
Low-frequency repetitive transcranial magnetic stimulation ( rTMS ) affects event-related potential measures of novelty processing in autism . In our previous study on individuals with autism spectrum disorder ( ASD ) ( Sokhadze et al. , Appl Psychophysiol Biofeedback 34:37-51 , 2009a ) we reported abnormalities in the attention-orienting frontal event-related potentials ( ERP ) and the sustained-attention centro-parietal ERPs in a visual oddball experiment . These results suggest that individuals with autism over-process information needed for the successful differentiation of target and novel stimuli . In the present study we examine the effects of low-frequency , repetitive Transcranial Magnetic Stimulation ( rTMS ) on novelty processing as well as behavior and social functioning in 13 individuals with ASD . Our hypothesis was that low-frequency rTMS application to dorsolateral prefrontal cortex ( DLFPC ) would result in an alteration of the cortical excitatory/inhibitory balance through the activation of inhibitory GABAergic double bouquet interneurons . We expected to find post-TMS differences in amplitude and latency of early and late ERP components . The results of our current study validate the use of low-frequency rTMS as a modulatory tool that altered the disrupted ratio of cortical excitation to inhibition in autism . After rTMS the parieto-occipital P50 amplitude decreased to novel distracters but not to targets ; also the amplitude and latency to targets increased for the frontal P50 while decreasing to non-target stimuli . Low-frequency rTMS minimized early cortical responses to irrelevant stimuli and increased responses to relevant stimuli . Improved selectivity in early cortical responses lead to better stimulus differentiation at later-stage responses as was made evident by our P3b and P3a component findings . These results indicate a significant change in early , middle-latency and late ERP components at the frontal , centro-parietal , and parieto-occipital regions of interest in response to target and distracter stimuli as a result of rTMS treatment . Overall , our preliminary results show that rTMS may prove to be an important research tool or treatment modality in addressing the stimulus hypersensitivity characteristic of autism spectrum disorders .
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Intervention_Physical
Low-frequency repetitive transcranial magnetic stimulation ( rTMS )
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Intervention_Physical
low-frequency , repetitive Transcranial Magnetic Stimulation ( rTMS )
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Intervention_Physical
low-frequency rTMS
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Outcome_Physical
parieto-occipital P50 amplitude decreased to novel distracters but not to targets
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Outcome_Physical
amplitude and latency to targets increased for the frontal P50 while decreasing to non-target stimuli
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Outcome_Physical
minimized early cortical responses to irrelevant stimuli
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Outcome_Physical
increased responses to relevant stimuli
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Outcome_Physical
better stimulus differentiation at later-stage responses
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Outcome_Physical
significant change in early , middle-latency and late ERP components at the frontal , centro-parietal , and parieto-occipital regions of interest in response to target and distracter stimuli
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Participant_Condition
autism
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Participant_Condition
ASD
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Participant_Sample-size
13