ADHD Research Today is a free monthly online journal that collates and summarizes the latest research about ADHD, including details on attention-deficit hyperactivity disorder, drugs, treatment, symptoms.

Abnormal latent inhibition and impulsivity in coloboma mice, a model of ADHD.

Bruno KJ, Freet CS, Twining RC, Egami K, Grigson PS, Hess EJ

Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.

Attention deficit hyperactivity disorder (ADHD) is characterized by hyperactivity, inattention, and impulsivity. The coloboma mouse model of ADHD exhibits profound hyperactivity. To determine whether coloboma mice exhibit other signs of ADHD, we assessed latent inhibition as a test of attention, and impulsivity in a delayed reinforcement paradigm. Latent inhibition was present in control mice but was disrupted in coloboma mice. Coloboma mice also exhibited impaired performance on the delayed reinforcement task and were not able to wait as long as control mice to obtain the greater reinforcer. Because norepinephrine mediates hyperactivity in coloboma mice, we examined the role of norepinephrine in disrupted latent inhibition and impulsivity. Reduction of norepinephrine with DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride) restored latent inhibition but did not ameliorate impulsivity. In summary, coloboma mice exhibit hyperactivity, inattention as determined by latent inhibition, and impulsivity, and norepinephrine mediates hyperactivity and inattention but not impulsivity in these mice.

Published 24 November 2006 in Neurobiol Dis, 25(1): 206-16.
Full-text of this article is available online (may require subscription).

© 2004-2008 ADHD Research Today. All Rights Reserved.