Altered motor network activation and functional connectivity in adult tourette's syndrome

Abstract

Tourette's syndrome (TS) is a developmental neuropsychiatric disorder characterized by motor and vocal tics as well as psychiatric comorbidities. Disturbances of the fronto-striatal-thalamic pathways responsible for motor control and impulse inhibition have been previously described in other studies. Although differences in motor performance are well recognized, imaging data elucidating the neuronal correlates are scarce. Here, we examined 19 adult TS patients (13 men, aged 22-52 years, mean = 34.3 years) and 18 age- and sex-matched controls (13 men, aged 24-57 years, mean = 37.6 years) in a functional magnetic resonance imaging study at 1.5 T. We corrected for possible confounds introduced by tics, motion, and brain-structural differences as well as age, sex, comorbidities, and medication. Patients and controls were asked to perform a sequential finger-tapping task using their right, left, and both hands, respectively. Task performance was monitored by simultaneous MR-compatible video recording. Although behavioral data obtained during scanning did not show significant differences across groups, we observed differential neuronal activation patterns depending on both handedness (dominant vs. nondominant) and tapping frequency in frontal, parietal, and subcortical areas. When controlling for open motor performance, a failure of deactivation in easier task conditions was found in the subgenual cingulate cortex in the TS patients. In addition, performance-related functional connectivity of lower- and higher-order motor networks differed between patients and controls. In summary, although open performance was comparable, patients showed different neuronal networks and connectivity patterns when performing increasingly demanding tasks, further illustrating the impact of the disease on the motor system.

Abnormalities in Resting-State Functional Connectivity in Early Human Immunodeficiency Virus Infection

“…This method, which optimizes detection of both diffuse, low-amplitude signals and sharp, focal signals, has been validated to provide improved sensitivity relative to other cluster-and voxel-based thresholding methods over a wide range of test signal shapes and SNR values (Smith and Nichols, 2009). This approach has been used in a number of recent studies ( Jolles et al, 2010;Mohammadi et al, 2011;Werner et al, 2010b).…”

Strengthened functional connectivity in the brain during muscle fatigue

“…Functional connectivity (FC) analysis, a method to measure the magnitude of functional coupling between brain regions, has recently gained many interests in human brain mapping studies (Baudrexel et al, 2011; Liu et al, 2008; Mayer et al, 2011; Werner et al, 2011). Although almost any measures of brain activity can be used to study FC (Rykhlevskaia et al, 2008), fMRI data are better suited for FC analysis because they provide both high spatial and reasonable temporal resolution, especially for submaximal-intensity muscle fatigue tasks that usually last for minutes.…”

Functional brain networks in movement disorders

“…Recent rs-fMRI findings suggest that these alterations might be caused by developmental immaturity of the neuronal pathways linking the major nodes of these networks [79,82 ▪▪ ]. Increased activity, predominantly in frontal and parietal regions, cingulate cortex, and caudate nucleus, might compensate for the functional decline in CSPTC and fronto-parietal circuits during voluntary movement [81,83]. Alternatively, it has been suggested that elevated activity in these regions as compared to healthy controls might rather display a failure to deactivate and thus reflect an immediate neural correlate of the motor manifestations of the disease [83].…”

“…Increased activity, predominantly in frontal and parietal regions, cingulate cortex, and caudate nucleus, might compensate for the functional decline in CSPTC and fronto-parietal circuits during voluntary movement [81,83]. Alternatively, it has been suggested that elevated activity in these regions as compared to healthy controls might rather display a failure to deactivate and thus reflect an immediate neural correlate of the motor manifestations of the disease [83]. Of note, distinct functional networks associated with specific symptoms of Tourette syndrome have recently been identified [82 ▪▪ ,84 ▪ ].…”