Hypofrontality is a state of decreased cerebral blood flow (CBF) in the prefrontal cortex of the brain. Hypofrontality is symptomatic of several neurological medical conditions, such as schizophrenia, attention deficit hyperactivity disorder (ADHD), bipolar disorder, and major depressive disorder. This condition was initially described by Ingvar and Franzén in 1974, through the use of xenon-enhanced CT scanning to image the brains of patients with schizophrenia. Subsequent neuroimaging work has shown that the decreases in prefrontal CBF are localized to the medial, lateral, and orbital portions of the prefrontal cortex. Hypofrontality is thought to contribute to the negative symptoms of schizophrenia. Research is currently being done on primarily humans and mice to learn more about hypofrontality. Hypofrontality was initially thought to be a side effect of antipsychotic drugs used to treat these conditions. However, reduced activity in the right frontal lobe, left temporal lobe and left cerebellum during the Wisconsin Card Sorting Test is seen in schizophrenic patients who have never received antipsychotic drugs, which suggests that this is not the case.