The ‘silent' mouse Verhage and his group posses, forms a unique tool for understanding one of the first steps of signalling by neurotransmitters. The mutant mouse has a defect in the docking mechanism of an intracellular vesicle, containing neurotransmitters, to the presynaptic membrane. The mutant therefore is derived of neuronal signalling.

Verhage explains the importance of this mutant mouse. “In this field of research, molecular neurobiology, there are a lot of mutants around, and there are perhaps over a hundred mutants which all display defects in of neurotransmitter secretion. We discovered the mutant mouse with the docking defect. It shows a genetic defect in a key protein that determines how the vesicle and the target find each other and establish a stable connection. And still there's only one mutant which only suffers from a docking defect, that makes our mutant extremely valuable.”

Also Verhage is interested in connectivity between brain parts. Impaired connectivity is thought to be correlated with psychiatric disorders. By GFP labeling serotonergic brain areas in mice, Verhage and colleagues study serotonergic neuron's projections. When this technique is combined with animal models for depression and anxiety, it should provide insight in underlying connectivity deficits.