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In contrast to findings from previous studies in older patients, resting motor threshold and variability of motor evoked potential responses in 17 TS subjects age 12-22 were increased versus controls, while the gain of motor excitability was reduced \cite{26934638}. The authors suggest that these findings may relate to delayed maturation of the cortical-cortical and corticospinal motor networks in TS.  Local field potentials (LFP) in the posterolateral globus pallidus pars interna (GPi) were recorded at rest and during tics and normal voluntary movements in 3 adults with TS during deep brain stimulation surgery and compared to GPi LFP recordings in four Parkinson disease patients off medication \cite{27733815}. Tics were associated with increased gamma (35-200 Hz) and high frequency (200-400 Hz) activity, and with cross-frequency coupling (between the phase of beta band activity and the amplitude of the high-frequency oscillations. oscillations).  Negative reinforcement learning is a key variable in theories of behavior therapies proven effective for TS. In this context, the findings of a 2016 report from Nottingham, England, are interesting. Behavioral and event-related potential data were collected during the learning of stimulus-response pairs using positive or negative reinforcement \cite{27103231}. Participants included children age 9-17 with TS, ADHD, both or neither. Lower accuracy and smaller P3 amplitudes were observed in association with ADHD but not TS.