Premonitory urges and tics in Tourette syndrome: computational mechanisms and neural correlates

- The somatosensory cortices and the insula are implicated in premonitory urges.
- The insula may serve as a gateway between premonitory urges and tics.
- Computationally, premonitory-urge termination elicits positive prediction errors.
- The insula, basal ganglia, and dopamine neurons interact to calculate those errors.
- Those prediction errors reinforce tics in the motor cortico-basal ganglia loop.

Tourette syndrome is characterized by open motor behaviors - tics - but another crucial aspect of the disorder is the presence of premonitory urges: uncomfortable sensations that typically precede tics and are temporarily alleviated by tics. We review the evidence implicating the somatosensory cortices and the insula in premonitory urges and the motor cortico-basal ganglia-thalamo-cortical loop in tics. We consider how these regions interact during tic execution, suggesting that the insula plays an important role as a nexus linking the sensory and emotional character of premonitory urges with their translation into tics. We also consider how these regions interact during tic learning, integrating the neural evidence with a computational perspective on how premonitory-urge alleviation reinforces tics.