Abnormalities in grooming behavior and tryptophan hydroxylase activity in the superior colliculi in cats with pontile and frontal neocortical lesions.

Cats with pontile or frontal neocortical lesions display a dissociation of the appetitive and consummatory components of grooming behavior when their body surface is tactually stimulated, an abnormal behavior that waxes and wanes with the seasons of the year. Tryptophan hydroxylase activity is significantly decreased in the superior colliculi of cats with pontile lesions and of cats with frontal neocortical lesions. The results suggest that the change in tryptophan hydroxylase activity is mediated neuronally and is a transneuronal effect on the serotonergic input to the superior colliculi. Pharmacological manipulations of the serotonergic system in normal cats failed to induce the abnormal behavior, indicating that other factors are involved in the genesis of the abnormal behavior.