Dr. Gerfen studies the functional organization of the cerebral cortex and basal ganglia. The basal ganglia are involved in transforming activity in the cerebral cortex into directed behavior. Using neuroanatomical tracing techniques, he mapped the connections of the circuits of this system, characterizing the compartmental nature of the input-output organization of the striatum, which is the main nucleus of the basal ganglia. His work established that the D1 and D2 dopamine receptors are segregated into two main pathways within the basal ganglia circuits. This finding forms a cornerstone of the predominant model of neurologic disorders affected by diseases of the basal ganglia, including movement disorders such as Parkinson's disease, chorea, and dystonia, and mental disorders such as attention deficit hyperactivity disorder and depression. Dr. Gerfen is a Co-Investigator on the Gene Expression Nervous System Atlas (GENSAT) project, with Nat Heintz at Rockefeller University. This project provides transgenic mouse lines to the neuroscience research community with neuron specific expression of Cre recombinase. Over 200 Cre-driver lines have been characterized with expression limited to specific neuron types or specific brain regions (http://www.gensat.org/cre.jsp) . Characterization of these lines is provided on the lab website: http://gerfenc.biolucida.net. Current work is focused on using BAC-Cre transgenic mouse lines to study the functional organization of the cerebral cortex and basal ganglia.