Dynamic Neuroimaging and Electrophysiological Studies of Motor Function in Tourette Syndrome

Grant Type
Grant Year
Institution Location
Institution Organization Name
Nat’l. Inst. On Deafness and Other Communication Disorders, NIH
Investigators Name
Braun, Allen, MD

The regions of the brain involved in the generation of motor or vocal tics in Tourette Syndrome remain obscure. Powerful neuroimaging and neurophysiological techniques have become available over the past decade which should help to pinpoint these regions, and have yet to be used to their full advantage to study TS motor function. Previous PET and SPECT studies have identified changes in activity in discrete regions of the brain which may be characteristic of TS patients and, by implication, could be involved in tic generation. These were resting studies, however, utilizing techniques in which multiple scans were precluded or in which functional information must be integrated over relatively long periods of time. These techniques have provided important baseline data, but do not lend themselves to dynamic studies of motor function. The H2150 PET rCBF technique makes it possible to measure quantitative regional cerebral blood flow (as an index of local synaptic activity) over very brief periods of time and to perform up to 10 scans in the course of a single study. This technique will make it possible to produce maps of brain activity during the expression of motor and vocal tics themselves, and to compare these with maps produced at rest and during the execution of voluntary movements. Comparison with control studies will help determine how central mechanisms associated with voluntary movement per se might differentiate TS patients and controls. The issue of whether or not premovement potentials, e.g. Breitschaftspotentials — as indices of voluntary vs. involuntary, or unvoluntary movements — precede the generation of tics (particularly complex tics) is only partially resolved. The H2150 PET images will be compared with high resolution (128 channel) premovement ERP studies performed during the same series of motor tasks. PET and ERP data will be compared using a common 3-dimensional frame of reference -i.e. the subjects’ own high resolution MRI. The combination of neuroimaging and electrophysiological data collected during the expression of motor symptoms themselves will be used to characterize the functional architecture of tic production, and may yield a testable working model of motor dysfunction in TS. Allen Braun, M.D. National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD Award $12,000 Tourette Association of America Inc. – Research Grant Award 1993