Network operations revealed by brain metabolic mapping in a genetic model of hyperactivity and attention deficit: the naples high- and low-excitability rats.

Genetic rat models are important for research on the neural networks of attention and emotionality. Naples-High Excitability (NHE) rats and Naples Low-Excitability (NLE) rats were investigated with random-bred (NRB) rats as controls. These rat lines were named for their respective behavior on spatial novelty tasks. Quantitative cytochrome oxidase (CO) histochemistry has been demonstrated to reflect long-lasting changes in tissue metabolic capacity. CO metabolic differences between the NLE and NHE were found in the granular cell layer of the outer blade of the dentate gyrus. In addition, NLE showed greater CO activity than NRB in medial frontal cortex, and lower activity in perirhinal cortex (dorsal region). NHE showed greater CO activity than NRB in entorhinal cortex (superficial layers) and lower activities in perirhinal cortex and cortical amygdala. These data support the hypothesis that NLE/NHE rats may be an appropriate model for studying genetically altered limbic regions related to impaired emotional processing. The results support the involvement of limbic circuits in attentive processes and impulsiveness, and support the use of the NLE and NHE strains as animal models of Attention Deficit Hyperactivity Disorder (ADHD) in children.