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We continuously adjust our movements to achieve our goals in an ever-changing environment. This flexibility can be the result of deliberate changes to behaviour, for example, when we strategically hit a tennis ball with higher momentum while playing against the wind. However, behavioural changes can also occur implicitly, without deliberation or intention; for example, when we automatically adjust the forces required after changing to a tennis racket with slightly different weight. Strategy-based and implicit learning can be dissociated in behavioural experiments, however, their underlying neural circuitry has remained poorly understood. Our goal is to understand the causal contribution of cerebello-thalamo-cortical circuits for implicit and strategy-based motor learning in humans. The cerebellum, thalamus, and motor cortex form a network that is critically involved in motor control, evident, for example, in essential tremor (ET). While tremor is their cardinal symptom, patients with ET also show reduced motor adaptation compared to healthy controls. Interestingly, motor adaptation problems are amplified in ET patients receiving deep brain stimulation of the ventral intermediate nucleus of the thalamus (VIM-DBS), a thalamic region functionally connected to the cerebellum and motor cortex. It is unknown if this cerebellum-VIM-motor cortex network is involved in implicit motor learning, strategy-based motor learning, or both. Our goal is to close this gap. We are currently examining patients with ET, treated with VIM-DBS, as well as age- and sex-matched healthy controls, in two behavioural experiments, one designed to isolate implicit learning, and the other strategy-based learning. Each patient completes each experiment in two sessions, with VIM-DBS turned ON vs. OFF (session order counterbalanced across patients). Both experiments (order counterbalanced across subjects) involve centre-out reaching movements to a visual target, with vision of the hand occluded by the experimental apparatus (KINARM End-Point lab). In the experiment that tests for strategy-based learning, the participants’ task is to adjust the aim point of their reach so that they move at a certain angle relative to a visual target, rather than straight towards the target. Specifically, the angle between movement and target should be identical to the angular offset between two lines shown on a computer screen at the beginning of each trial, in a different part of the workspace. The task thus involves the strategy-based learning system (i.e., an aiming strategy). In the experiment that tests for implicit learning, a visual cursor is presented as participants reach to the target. The radial position of the cursor is aligned with the moving hand. However, the angular position of the cursor follows a pre-specified angle with respect to the target. Participants are informed that the angular direction of the cursor is fixed and independent of the direction of their hand movement. They are instructed to ignore the cursor and reach directly to the visual target. Changes in reach angle are attributed to the automatic operation of the implicit learning system. Based on previous evidence that the cerebellum is involved in both strategy-based and implicit learning, we hypothesize that VIM-DBS impairs both learning types.