The aim of this study is to describe the interaction of the cognitive and visual-cognitive task with postural stability in patients suffering by cerebellar ataxia. Investigators will measure changes in postural stability parameters and in secondary task performance, which should show the ability of the patients to manage the dualtask situations.

The aim of this research will be to describe the interaction between cognitive and cognitive sensory tasks and stability in patients whose disease impairs the ability to maintain a stable upright position, for example in patients with cerebellar syndromes. And further compare this interaction with a control group of healthy probands. This interaction will be investigated in variously demanding postural situations (eg. standing on both lower limbs, with the exclusion of visual control, with reduced proprioceptive input from the patch).

Patient stability will be quantified using a stabilometric examination on the Kistler platform (Kistler Instrumente AG, Switzerland). investigators will quantify the performance of patients in secondary tasks using parameters such as response time to response and success in assigned tests.

The expected number of probands is 20 individuals in both groups. Study will objectify postural stability by means of a static stabilometric examination on the Kistler platform, the recording length of each postural situation will be 30 s. Four different demands of postural tasks were chosen - a bipedal stand, a bipedal stand with the exclusion of visual control, a stand on a foam pad and a stand on a foam pad with the exclusion of visual control. To evaluate postural deviations, investigators chose the following CoP parameters: stabilogram curve length and stabilogram area. During the stabilometric measurement, the number of touches of the guardrail will also be recorded, or the number of falls or touches with a lightened limb of the pad or the other limb during the measurement. Testing will take place in the Neurological Laboratory of the Department of Neurology, 2nd Faculty of Medicine, Charles University in Prague and FN Motol.

Gradually, two types of secondary task will be added to the postural tasks, with visual input (modified Stroop test) and a purely cognitive task (Backward counting test). At first, probands will be acquainted with what types of tasks await them during the experiment and will be able to train each of them in two trial experiments. This will be followed by testing trials in random order (cognitive tests in single-task situations, namely sitting in a chair, single task postural tasks and dual-task situations).

Inclusion Criteria:

• 3 Hz tremor in in frequency analysis (posturografy)
• stability disorder caused by cerebellar disorders in diagnose

Exclusion Criteria:

• lower than high school education
• vestibular disorders
• ankle instability
• other specific stability disorders
• unability to stand for 30s