development of an animal model for attention deficit hyperactivity disorder: Effects of frontal lesions on activity in neonatal rats

This study was designed to develop an animal model of Attention Deficit Hyperactivity Disorder based on frontal cortical functioning in 3, 6, 9, & 12-day-old neonatal rats. In Expt. 1, frontal cortical activity was suppressed with intracranial injections of lidocaine, a local anesthetic. In Expt. 2, frontal activity was suppressed with brain transections. Pups in both experiments were tested in a habituation-to-odor learning paradigm and behaviors including general activity, headwaving, probing, and rolling were recorded. Results indicated that frontal cortical suppression, caused by either lidocaine injection or brain transection, resulted in significantly higher activity levels in 3-day-olds particularly with regard to rolling, suggesting that the frontal cortex is involved in the regulation of rolling behavior. Frontal transections, but not lidocaine injections, also significantly increased activity in 12-day-old pups due to increased locomotor probing and wall climbing. Results are consistent with the neuropsychological research regarding frontal cortical functioning and inhibition in children with ADHD, and show potential as a future animal model of ADHD.