Rebecca J Mazzullo

Publications (2)5.87 Total impact

• Source

  Available from: Larry W Hawk

  Article: Effects of methylphenidate on discounting of delayed rewards in attention deficit/hyperactivity disorder.

  Keri Shiels, Larry W Hawk, Brady Reynolds, Rebecca J Mazzullo, Jessica D Rhodes, William E Pelham, James G Waxmonsky, Brian P Gangloff
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  ABSTRACT: Impulsivity is a central component of attention deficit/hyperactivity disorder (ADHD). Delay discounting, or a preference for smaller, immediate rewards over larger, delayed rewards, is considered an important aspect of impulsivity, and delay-related impulsivity has been emphasized in etiological models of ADHD. In this study, we examined whether stimulant medication, an effective treatment for ADHD, reduced discounting of delayed experiential and hypothetical rewards among 49 children (ages 9-12 years) with ADHD. After a practice day, participants completed a 3-day double-blind placebo-controlled acute medication assessment. Active doses were long-acting methylphenidate (Concerta), with the nearest equivalents of 0.3 and 0.6 mg/kg TID immediate-release methylphenidate. On each testing day, participants completed experiential (real-world money in real time) and hypothetical discounting tasks. Relative to placebo, methylphenidate reduced discounting of delayed experiential rewards but not hypothetical rewards. Broadly consistent with etiological models that emphasize delay-related impulsivity among children with ADHD, these findings provide initial evidence that stimulant medication reduces delay discounting among those with the disorder. The results also draw attention to task parameters that may influence the sensitivity of various delay discounting measures to medication effects.
  Experimental and Clinical Psychopharmacology 10/2009; 17(5):291-301. · 2.58 Impact Factor
• Source

  Available from: Larry W Hawk

  Article: Motivated attention: incentive effects on attentional modification of prepulse inhibition.

  Rebecca L Ashare, Larry W Hawk, Rebecca J Mazzullo
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  ABSTRACT: Prepulse inhibition (PPI) of startle is greater for attended compared to ignored prestimuli, and, consistent with theories of motivated attention, initial evidence suggests that this effect is greater among participants given performance-based incentives. The present study examined a within-subjects incentive manipulation. Participants (n=41) completed two blocks of a tone discrimination task. During the incentive block, participants received trialwise feedback with small monetary incentives for task performance. Startle eyeblink EMG responses to auditory probes were assessed at 60-, 120-, and 180-ms tone-probe stimulus onset asynchronies (SOAs). As predicted, PPI was enhanced during attended compared to ignored prestimuli only at the 120-ms SOA in the incentive condition. There was no evidence of attentional modification in the no-incentive condition. These data suggest that attentional modification of PPI is sensitive to within-subjects manipulations of incentive, providing a useful tool for testing models of motivated attention in psychopathology and psychopharmacology.
  Psychophysiology 12/2007; 44(6):839-45. · 3.29 Impact Factor