Increased sensorimotor noise in Tourette syndrome.

Area of Science:

• Neuroscience
• Neurology
• Clinical Neurophysiology

Background:

• Tourette syndrome (TS) is a neurological disorder marked by motor and vocal tics.
• Pathophysiology of TS is linked to reduced striatal inhibitory GABAergic interneurons, potentially increasing neural noise in the cortical-striatal-thalamic-cortical circuit.
• Neural noise, defined as trial-by-trial variability in neural responses, is a potential biomarker for neurological conditions.

Purpose of the Study:

• To investigate increased neural noise in adults with Tourette syndrome using electroencephalography (EEG).
• To assess trial-by-trial variability in somatosensory evoked potentials (SEPs) in individuals with TS compared to neurotypical controls.

Main Methods:

• Utilized EEG to measure neural responses to median nerve electrical stimulation in 19 adults with TS and matched controls.
• Operationalized neural noise as increased trial-by-trial variability in the magnitude and/or timing of SEPs.
• Analyzed early- and mid-latency SEP components (N20, P45, N60, P100) and their variability.

Main Results:

• The P100 SEP component, linked to tactile perception, was significantly increased in the TS group.
• While early/mid-latency SEP timing and topography did not differ, trial-by-trial variability was substantially higher in the TS group at rest.
• This increased neural variability in TS normalized during somatosensory stimulation.

Conclusions:

• Individuals with Tourette syndrome may have less stable recruitment of sensorimotor neuronal populations at rest.
• Neural noise in TS appears to be stimulus-dependent, normalizing with somatosensory input.
• These findings offer insights into the neural underpinnings of Tourette syndrome and potential therapeutic targets.