Over the past century researchers have attributed the symptoms that today are labeled as Tourette syndrome to various etiologies. Although most investigators have accepted Gilles de la Tourette's initial description of a symptom complex of tics and involuntary vocalizations, most have rejected his claim that “tic disease” resulted from hereditary degeneration. Subsequent investigators have offered an array of contradictory etiological explanations including viewing these symptoms as a subset of choreas, a result of insufficient inhibition, a failure to control infantile habits, a sequel to encephalitis and other infections, or the result of unconscious psychosexual childhood conflict. With the advent of effective pharmacologic treatments in the 1960s, psychiatrists, often urged on by the parents of afflicted children, began to insist that the disorder resulted from organic factors, most likely connected to transmission of the neurotransmitter dopamine and signaling in the basal ganglia. Since the 1970s, research has focused on a variety of possible organic substrates, but disputes over which symptoms to include in the syndrome's phenotype continue to constrain efforts to locate its etiology.