Bhikram and colleagues reported a resting-state fMRI study in TS that included 39 TS patients and 20 controls, analyzed using seed-based functional connectivity (fcMRI) methods \citep{32065948}. The TS group showed greater connectivity between the temporal gyri, insula and putamen, and between orbital frontal cortex (OFC) and cingulate cortex. Tic severity correlated with increased connectivity of the putamen with sensorimotor cortex. By contrast, OCD severity correlated with decresae connectivity between SMA and thalamus and between caudate and precuneus. Finally, premonitory urge severity correlated with decreased connectivity between OFC and primary sensorimotor cortext, and inferior frontal gyrus correlated with putamen and insula. Perhaps surprisingly, even though only the first symptom domain reflects actual movement, all three symptom-related networks include sensorimotor regions.
Zapparoli and colleagues reported two interesting studies of the experience of agency, i.e. the appreciation that we intentionally acted and our actions caused the observed consequences \citep{32937445,33409491}. These studies involved 25 adults with TS and 25 tic-free control participants, and used an implicit, indirect measure of agency called the intentional binding phenomenon, in which people judge the delay between an action (e.g., pressing a button) and its effect (e.g., the turning on of a light) to be shorter with intentional than with passive movement. The earlier report gives results from tic-free participants studied with fMRI and TMS to the pre-supplementary motor area (pre-SMA). The second report shows that the TS group did not show significant intentional binding or correlation with activity in the network identified in the control group. The authors interpret the results as consistent with impaired action monitoring and an impaired sense of agency in TS, which may contribute to the perception of some people with TS that tics are fully involuntary.