Neuromodulation of Social Skills in Childhood Ataxia
Neuromodulation of Social Skills in Childhood Ataxia
The present study aims to define a protocol of electrical stimulation of the cerebellum via
 transcranial direct current stimulation (tDCS) combined with a virtual reality protocol to
 assist the rehabilitation of social skills in adolescents and young adults with childhood
 ataxia.

 Taking into account the high neuronal density of the cerebellum, its strong connection with
 the cerebral cortex, and its involvement in motor, cognitive and affective processes, as well
 its involvement in social prediction abilities, the investigators hypothesized that
 excitatory stimulation of the cerebellum might improve social prediction abilities in
 adolescents and young adults with childhood ataxia. Moreover, as suggested by previous
 studies investigating the effect of tDCS in paediatric population, the investigators expected
 that tDCS will be safe and well tolerated. Such a result would encourage the use of
 non-invasive brain stimulation in the rehabilitation of social skills in childhood ataxia.
The investigators planned a single centre, randomized stratified, double-blind, sham-
 controlled design.

 Adolescents and young adults with childhood ataxia will be recruited and randomly assigned to
 two different groups: the active-tDCS group and the sham-tDCS group. Each group will undergo
 a multi-sessions (8 sessions) intervention during which tDCS will be delivered over the
 cerebellum. The stimulation will be paired with a virtual reality VR training. The Virtual
 Reality (VR) training will exploit a design based on probabilistic learning of social events
 in child-friendly environments. During the training, participants will be asked to conquer
 some goal/objects by predicting the behaviour of some competing virtual avatars whose actions
 should be probabilistically learned. Based on the same structures, two different
 child-friendly scenarios will be created and they will be respectively used in the pre- and
 in the post-training evaluation sessions (scenario A) or in association with the tDCS
 protocol throughout the 8 sessions of intervention (scenario B).

 Participants' abilities of social prediction (primary outcome) will be tested through a
 validated computer based Action prediction task assessing participants' abilities in
 predicting others' actions based on previous experience. This experimental paradigm comprises
 a probabilistic learning (familiarization) phase and a testing phase. In the familiarization
 phase participants are asked to observe an actor performing two different types of grasping
 actions (such as grasping movement of an apple for eating the apple or for offering the apple
 to another partner) in different colour-cued contexts. They are asked to recognise actor's
 intention.

 Crucially, the probability of co-occurrence between one action and the colour-cued context is
 implicitly biased with pre-established probability of association. In the testing phase, the
 same videos are presented but their length is dramatically shortened via temporal occlusion
 before the action is completed. In this way, since the movement kinematics is ambiguous, an
 observer would use the previously learned association with context to predict the fate of the
 action, and responses should be biased toward the contextual priors. A control non-social
 prediction task with a similar structure will be also used. A standard neuropsychological
 assessment (NEPSY-II) before and after the training will allow assessing the generalizability
 of the effects to general social perception abilities, in particular Theory of Mind and
 affect recognition (Secondary Outcomes). In the post-training and in the follow-up evaluation
 session (one month after the end of the intervention) the training acceptability and the
 quality of life assessments will be performed.

 The protocol will allow testing the efficiency of the combined tDCS+ VR training in:

 -  enhancing social prediction abilities in childhood ataxia;

 -  enhancing implicit learning abilities, even in non social contexts;

 -  improving theory of mind abilities;

 -  improving patients' quality of life;

 -  further investigating the safety and tolerability of tDCS.
Inclusion criteria:

 -  Adolescents and young adults who aged 11-25 years

 -  Childhood ataxia

 -  Intelligence Quotient > 80

 Exclusion Criteria:

 -  Presence of contraindication to tDCS (history of epilepsy, migraine, severe brain
 trauma; presence of metal in the brain/skull or implanted neurostimulator, cardiac
 pacemaker; state of pregnancy)

 -  Intake of or withdrawal from some drugs potentially changing the seizure threshold

 -  Presence of comorbidity with an important medical conditions

 -  Severe sensorial, motor and/or behavioural problems that could interfere with the use
 of GRAIL/VR technology