In patients with Gilles de la Tourette syndrome (GTS), both procedural sequence learning and event file binding are improved and are potential cognitive mechanisms behind habitual symptoms such as tics and contribute to the overall cognitive profile of these patients, according to a review published in the European Journal of Neuroscience.
As a complex neuropsychiatric disorder, GTS is associated with motor and vocal tics as well as cognitive changes. Previous studies have shown that internal or external sensory stimuli can trigger habitual behavior. While several studies have examined the processing of stimulus-response associations in patients with GTS, it has been suggested that these associations are facilitated in some studies and impaired in others.
The current review focused on 2 enhanced functions as potential cognitive mechanisms behind habitual behavior in patients with GTS: procedural memory formation and encoding of event files.
Procedural memories are built through repeated exposure to regularities in the environment; This creates persistent long-term memory traces and relies on the predictability of the events. The formation of habits involves the consequences of stimulus-response associations and specific brain structures. Thus, procedural learning and memory have the essential qualities to enable a cognition-driven understanding of habitual behavior.
While procedural learning describes how habits develop as long-term memory, event file binding describes habit formation at the level of individual stimulus-response relationships, regardless of longevity. Binding event files can cause changes in episodic memory traces, creating a link between event file encoding and declarative memory.
The data suggest that striatal functions, such as event file binding and procedural learning, can shed light on habit and tic formation in patients with GTS.
Learning is intact or even improved in children and adolescents with GTS, suggesting procedural hyperfunction in adults with neuropsychiatric disorder.
Event files are the building blocks of procedural reminders; consequently, abnormal attachment would result in abnormal procedural memory. Improved event file binding can lead to hyperlearning of sequential regularities in GTS. Hyperlearning leads to abnormally stable procedural memories that persist long after their original meaning. In addition, previous studies have shown a positive correlation between the magnitude of the attachment effect and the motor tic frequency.
It is possible that event file binding and procedural learning in GTS “could”  Sides the same coin. “On the one hand, hyperbinding explains the emergence of strong stimulus-response connections; on the other hand, hyperlearning explains the retention of event files over a larger time frame.
“Converging evidence for improved functions in GTS is probably no coincidence and, in addition to understanding GTS, also has ramifications for cognitive theories. Despite their similarities, event file binding and procedural sequence learning have different time scales and different sensitivities to potential interference in action sequencing, but both contribute to the overall cognitive profile of GTS, ”the study researchers concluded.
Takacs A, Münchau A, Nemeth D, Roessner V, Beste C. Lower-level associations in Gilles de la Tourette syndrome: convergence between hyperbinding of stimulus and reaction characteristics and procedural hyperfunction theories. Eur J Neurosci. Published online June 21, 2021. doi: 10.1111 / ejn.15366