Looking for a neurophysiological marker of Autism Spectrum

Disorders in Infants and Toddlers

Julia M. Stephen, PhDMRN Research Scientist

babySQUID – a unique pediatric MEG system

•MEG provides exquisite temporal resolution (same as EEG, much better than fMRI) and good spatial resolution (better than EEG not quite as good as fMRI).

•The prototype babySQUID is the only infant/toddler MEG system; designed by Dr. Yoshio Okada, Professor, Dept. Neurology UNM

3 year old child

Plastic modelof infant skull

Source localizationUsing MEG

In search of an early marker for Autism Spectrum Disorders (ASD)

• ASD prevalence has increased dramatically over the last two decades

• Based on epidemiological studies, this increase cannot be explained by increased clinician awareness.

• While there is a known genetic link to ASD due to higher risk of ASD within families, this alone does not explain the increase.

• Although the medical community agrees that there is likely not a direct link between mercury in vaccines and ASD, with increased industrialization there are a lot of known neurotoxins to which children are exposed, including heavy metals.

• Current widely accepted hypothesis suggests a genetic susceptibility with environmental trigger(s).

Behavioral diagnosis versus Intervention

• ASD is diagnosed using behavioral testing, which is variable:

• Hunger, sleep, illness, environment, stranger anxiety

• These diagnoses do not occur until much later than the initial signs of developmental delay.

• Variability in the timing of developmental milestones leads to “wait and see.”

•Minshew and Williams (2007) review suggests reduced brain connectivity associated with ASD

•Impairment in multisensory processing abilities has been shown using behavioral tasks in ASD children (aged 2-10 years).

•Multisensory integration deficits in children with autism could be a sensitive marker of atypical brain development. Minshew and Williams 2007 Neurobiol Rev

ASD Preliminary Results

•All subjects (N = 15) showed an enhanced sensory integration response with synchronous tone and touch.

•The difference in latency across age is significant.

•The longer latency for ASD approached significance with N=3 (p = 0.06).

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* Murray et al. 2005 Cerebral Cortex

1. A brief tone was presented to the child while sleeping (A).

2. A light touch from a balloon was presented (S).

3. Both the tone and the touch stimuli were presented synchronously (AS).

A Multidisciplinary Approach…

• Early diagnostic behavioral testing (Dina Hill and Brian Lopez).

• Awake behavioral experimental measures of multisensory processing (David Witherington).

• Measures of heavy metal exposure through a survey and hair and finger nail samples for testing (Andrea Allan).

• Genetic information through saliva samples (J. Stephen and Andrea Allan through MRN neurogenetics lab – K. Hutchison).

• Neurophysiological measures of multisensory processing in sleeping children using the babySQUID MEG system.