The somatotopy of tic inhibition: Where and how much?

TY - JOUR

T1 - The somatotopy of tic inhibition: Where and how much?

AU - Ganos, Christos

AU - Bongert, Jens

AU - Asmuss, Luisa

AU - Martino, Davide

AU - Haggard, Patrick

AU - Münchau, Alexander

N1 - © 2015 International Parkinson and Movement Disorder Society.

PY - 2015/8

Y1 - 2015/8

N2 - BACKGROUND: Tics are the hallmark feature of Tourette syndrome. The basic phenomenological and neurophysiological characteristics of tics have been widely investigated. Interestingly, the spatial distribution of tics across different body parts has received little attention. No previous study has investigated whether the capacity for voluntary tic inhibition also varies across body parts.METHODS: We analyzed video sequences of 26 adolescents with Tourette syndrome in a "tic freely" condition, and in a "voluntary tic inhibition" condition, to obtain absolute tic counts for different body parts. Two measures of the spatial distribution of tics were then analyzed. Linear regression analyses were employed to investigate the relation between the contribution of each body part to overall tic behavior and the ability to inhibit tics in that body part, averaged over our patient group.RESULTS: Tic distribution across patients showed a characteristic somatotopic pattern, with the face most strongly represented. A significant negative relation was found between the ability to inhibit tics and pooled tic frequency across body parts. The body parts that exhibited the fewest tics were the ones for which tic inhibition was most effective.CONCLUSIONS: Our data are consistent with the idea that tic recruitment order reflects a "tic generator" spreading across a somatotopic map in the brain. Voluntary tic inhibition did not simply cause a proportional reduction of tics in each body part. Rather, the least affected body parts showed most effective voluntary tic inhibition. The results are discussed in terms of signal and noise within cortical-subcortical motor loops.

AB - BACKGROUND: Tics are the hallmark feature of Tourette syndrome. The basic phenomenological and neurophysiological characteristics of tics have been widely investigated. Interestingly, the spatial distribution of tics across different body parts has received little attention. No previous study has investigated whether the capacity for voluntary tic inhibition also varies across body parts.METHODS: We analyzed video sequences of 26 adolescents with Tourette syndrome in a "tic freely" condition, and in a "voluntary tic inhibition" condition, to obtain absolute tic counts for different body parts. Two measures of the spatial distribution of tics were then analyzed. Linear regression analyses were employed to investigate the relation between the contribution of each body part to overall tic behavior and the ability to inhibit tics in that body part, averaged over our patient group.RESULTS: Tic distribution across patients showed a characteristic somatotopic pattern, with the face most strongly represented. A significant negative relation was found between the ability to inhibit tics and pooled tic frequency across body parts. The body parts that exhibited the fewest tics were the ones for which tic inhibition was most effective.CONCLUSIONS: Our data are consistent with the idea that tic recruitment order reflects a "tic generator" spreading across a somatotopic map in the brain. Voluntary tic inhibition did not simply cause a proportional reduction of tics in each body part. Rather, the least affected body parts showed most effective voluntary tic inhibition. The results are discussed in terms of signal and noise within cortical-subcortical motor loops.

U2 - 10.1002/mds.26188

DO - 10.1002/mds.26188

M3 - SCORING: Journal article

C2 - 25786675

VL - 30

SP - 1184

EP - 1189

JO - MOVEMENT DISORD

JF - MOVEMENT DISORD

SN - 0885-3185

IS - 9

ER -