The general objective being to determine the modifications nature induced by upper extremity kinematic rhythmic task realization on cervical HSCC.

The obtained knowledge could open up new prospects for rehabilitation in cerebro-injured subjects in addition to existing therapeutics.

Half of all stroke patients have physical disabilities. These disabilities combine sensory and motor deficiencies (control deficit, syncinesia, tone disorders) that cause disruption of upper extremity (UE) function (orientation, UE length adjustment and grip). The human spinal cord circuitry (HSCC) participate in the motion regulation. Roche et al. studied in healthy subjects the HSCC modifications during the visuo-motor regulation of the object clamping force by the hand. The authors showed that the learning of the task in a single session was associated with HSCC modifications, specific or not depending on the HSCC and according to a visual biofeedback associated or not to the task. Diserens et al. showed also that a rhythmic movement of UE pedaling causes a decrease in spasticity in hemiplegic subjects. Moreover, HSCC modification is dependent on the task performed. The rhythmic ball-bouncing in a virtual environment is a visuo-motor task rhythmic kinematic already studied in the healthy subject. To our knowledge, the present study is the first to investigate HSCC modification in hemiplegic subjects performing a rhythmic kinematic task with UE. We hypothesize that such a task leads to HSCC excitability specific modifications in the cervical spinal cord and leads to an improvement in the motor capabilities of the subjects.

The general objective being to determine the modifications nature induced by UE kinematic rhythmic task realization on cervical HSCC, our research will be broken down into four studies.

Study 1 will identify the influence of visual feedback on changes in HSCC excitability in a voluntary group. In this first study, 16 voluntary subjects will perform the visuo-motor task with their dominant UE and the control task (without visual feedback) with their dominant UE.

Study 2 will investigate the impact of UE laterality which performing the task on changes in HSCC excitability in a voluntary group. In this second study, 16 volunteer subjects will perform the visuo-motor task with their dominant UE and the visuo-motor task with their non-dominant UE.

Study 3 will objectify the effect of the type of contraction of the muscles involved in the task on changes in HSCC excitability in a volunteer group. In this third study, 16 voluntary subjects will perform the visuo-motor task with their dominant UE by performing either elbow flexion-extension or only flexion-extension of the wrist.

Finally, study 4 will study the effect of the pathology and the motor strategies used on the changes in HSCC excitability. In the latter study, 16 hemiplegic patients will perform the visuo-motor task with their paretic UE and spontaneous motor strategies.

The obtained knowledge could open up new prospects for rehabilitation in cerebro-injured subjects in addition to existing therapeutics.

Inclusion Criteria:

Hemiplegic subjects:

• Informed consent signature,
• Male or female aged 18 years or over,
• Hemiplegic patient with single stroke,
• Patient able to stand without technical assistance,
• Patient capable of performing an active elbow flexion/extension movement of an amplitude of at least 45° against gravity,
• Patient able to understand and realize the cyclical kinematic rhythmic task.
• Absence of cognitive impairment, Mini-Mental State score (MMS) equal to 30.

Voluntary subjects:

• Informed consent signature,
• Male or female aged 18 years or over,

Exclusion Criteria:

Hemiplegic subjects:

• Refusal to participate in the study,
• Inability to cooperate,
• Intervention on the studied upper limb dating less than 6 months,
• No affiliation to a social security scheme,
• No H-reflex in the muscle Flexor Carpi Radialis,
• Epilepsy antecedent.in the year prior to inclusion.

Voluntary subjects:

• Refusal to participate in the study,
• Inability to cooperate,
• Intervention on the studied upper limb dating less than 6 months,
• No affiliation to a social security scheme,
• No H-reflex in the Flexor Carpi Radialis muscle,
• Ambidextrous subject,
• Epilepsy antecedent.