About this trial
The CERSTIM study is a physiopatholgical study investigating transcranial alternating current stimulation in stroke patients in the cerebello-motor loop.
The design is a cross over design testing two frequencies in the gamma band and one placebo.
We will use behavioural data, functional MRI, and Electroencephalography to disentangle the effect of tACS and its frequency.
Healthy participants will be also recruited.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Male or female aged 18 years or older on the day of inclusion.
Affiliated with a social security system, Universal Health Coverage (CMU), or any equivalent scheme.
Ischemic stroke or intraparenchymal hematoma that occurred more than 6 months ago, with no upper time limit.
Motor deficit of the upper limb confirmed by the ARAT scale, with the ability to grip and press on a tablet.
Disqualifiers
Total paralysis of the affected hand
Conditions that are life-threatening or could compromise follow-up during the study period
Contraindications to MRI and tACS (ferromagnetic surgical clips, ocular implants, intraocular or nervous system metallic foreign bodies, implants or metallic objects likely to concentrate the radiofrequency field, cochlear implants, brain or cardiac stimulators, presence of a craniotomy scar)
Participation in another biomedical study focused on motor or overall recovery during the same period, or current exclusion period from another biomedical study
Trial design
Crossover
Treatments tested in this trial
tACS Transcranial alternating stimulation
Devicesession of 20 minutes
Treatment groups
Trial outcomes
Primary outcomes
change in activation in the primary motor cortex and cerebellum using functional magnetic Resonance
The activity of cerebellomotor regions is measured in functional task MRI with a hand motor task performed in the machine (squeezing a handle). The average BOLD signal in the cerebellum and M1 regions is measured using a general linear model adapted to functional MRI images such as SPM and its toolboxes.
Secondary outcomes
comparison between activation in the primary motor cortex and cerebellum using functional magnetic Resonance with the 50 Htz versus the 70 Htz frequency
The measurement method is identical to that used for the primary endpoint. Only the final statistical test changes (comparison of differences between each session). final change statistics (comparison of difference between each session).
change in functional connectivity between the primary motor cortex and cerebellum using functional magnetic Resonance
The measurement method is based on functional task MRI. It involves a z-score of the correlation between the signal of 2 regions in time belonging to the motor network.
change in functional connectivity using EEG after intervention and comparison between frequencies of tACS
The measurement method will be functional connectivity measured by an index called wSMI (weighted-Symbolic Mutual Information), which is an EEG marker. EEG data will be collected via the Starstim Neuroelectrics system and analyzed using in-house scripts (developed in-house) in Matlab and Python before and after each session, and we will also compare differences in change between the two sessions.
change in behaviour after intervention and comparison between frequencies of tACS
behaviour will be assessed on a motor learning task (accuracy, reaction time). The measurement method will be a SRT (serial reaction time) task with visuomotor adaptation where the subject must obey these instructions. Error rate and reaction time will be measured. will be measured.
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