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Yarden Dankner, Lilach Shalev-Mevorach, Marisa Carrasco, Shlomit Yuval-Greenberg; Pre-stimulus inhibition of microsaccades in adults with and without ADHD as an index for temporal expectations. Journal of Vision 2016;16(12):598. doi: https://doi.org/10.1167/16.12.598.
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Introduction: Attention Deficit Hyperactivity Disorder (ADHD), a behavioral disorder characterized by inappropriate levels of inattention, hyperactivity and impulsivity, consists of a diverse combination of cognitive deficits, and not all individuals diagnosed with ADHD present all deficits. For instance, many people with ADHD experience difficulties in sustaining attention over time but this impairment is not evident in every individual. Recent studies suggest that ADHD is associated with an impaired ability to anticipate predicable events. Our hypothesis is that the impairment of temporal expectation is related to deficits in sustained attention and therefore the two impairments are expected to co-occur in the same individuals. We utilized a novel approach for studying temporal expectation by examining the inhibition of microsaccades (saccades < 1deg), prior to the onset of predicted stimuli. Methods: 20 participants diagnosed with ADHD and 20 neurotypical participants performed two Continuous Performance Tasks (CPTs) with fixed and random inter-stimulus intervals, while their eye movements were recorded. We estimated "predictive microsaccade inhibition" (PMSI) by comparing microsaccade-rate prior to predictable stimuli (presented in fixed intervals) with microsaccade-rate prior to unpredictable stimuli (presented in random intervals). We divided each group of observers according to their sustained attention performance into two subgroups: 'high' performers and 'low' performers. Results: We found that: (a) Individuals with ADHD showed a smaller PMSI than controls. (b) Within each group, the PMSI was significantly stronger for high- than low-performers. But, when dividing each group according to the Adult ADHD Self-Report scale (ASRS), no such difference was observed. Conclusions: The results show that sustained attention is tightly linked to temporal expectations, as measured by PMSI. The attenuated PMSI in ADHD may impair performance. These results demonstrate that PMSI can be a powerful tool for studying temporal expectations in clinical and neurotypical populations.
Meeting abstract presented at VSS 2016
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