Functional Neuroimaging study of Prepulse Inhibition in Tourette Syndrome

Grant Type
Grant Year
Institution Location
Institution Organization Name
Yale Child Study Center
Investigators Name
Crowley, Michael, PhD

The precise neuropathophysiology that underlies Tourette Syndrome (TS) remains to be fully understood. The basal ganglia are a set of nuclei deep within the brain that have been implicated in TS. In striking parallel, animal and human studies implicate the basal ganglia as part of the neurophysiological basis for prepulse inhibition of the startle reflex. The startle reflex is a protective behavioral reaction consisting of rapid extension and flexion of a series of muscles of the eyelid, the neck and extremities. Prepulse inhibition (PPI) is a simple behavioral measure of inhibition (reduction) of the blink reflex that happens when a stimulus (prepulse) occurs 30 to 500 milliseconds before a startling stimulus. Conceptually, the prepulse stimulus is believed to activate automatic brain mechanisms that serve to protect that stimulus for a brief window of time. Motor responses occurring during the “protected period” are thought to be suppressed or “inhibited.” PPI of the blink startle response has been demonstrated to be reduced in patients with TS compared to normal controls. Thus, prepulse inhibition of the startle response is an ideal measure for probing the neuropathophsiology underlying TS. The goal of our current research study is to utilize a PPI paradigm in a functional neuroimaging context to further our understanding of the neurophysiology that underlies TS. We hypothesize reduced activation in the basal ganglia during our startle task will be associated with decreased PPI in TS patients. In our study design, we will use fluorescent MRI to compare adult patients with TS and adults with a history of TS who are now tic free with age and sex matched people who have never had TS. Differences across these groups in terms of PPI strength and basal ganglia activity during PPI may provide a marker for neuropsychological differences present among TS patients related to symptom presence or persistence into adulthood. These markers would also be important in future genetic, neuroimaging and clinical studies of TS. Michael J. Crowley, Ph.D., Michael H. Bloch, M.D. Yale Child Study Center, New Haven, Connecticut Award: $75,000 Tourette Association of America Inc. – Research Grant Award 2005-2006