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Développement d'interfaces cerveau machine visant à compenser les déficits moteurs chez des patients tétraplégiques. Etudes expérimentales précliniques

Abstract : Brain computer interface with chronic cortical electrode arrays for motor deficit compensation in motor disabled patients. Experimental study in rodents. A brain-computer interface (BCI) is currently defined as a hardware and software communication system that permits cerebral activity alone to control external devices. The immediate goal of BCI research is to provide communication capabilities to severely disabled people who are totally paralyzed or ‘locked in' by neuromuscular disorders, such as amyotrophic lateral sclerosis, brain stem stroke, or spinal cord injury. Promising results (patients piloting a joystick through modulation of their cortical activity) increase the hope of BCI with an array of microelectrodes chronically implanted at the cortex's surface, which doesn't exist yet. Recent experiments demonstrated the capacity for a tetraplegic to control a robotic arm. This PhD work contributes to preclinical studies, performed in parallel of technical development to provide validation of the human experimental protocol in successive steps. It contributes to develop ECoG recording device for rats, to implant them in the corresponding animals and record their ECoG activity during freely moving behavioural experiments to control an external effector. Two kinds of on-line studies have been done: the control of the dispenser directly by cortical activity or by the combination of motor task (push the lever) and detection of the signature. In studies of direct control by the detection the Overall Performance (OP) was 21,01%±4,33 (10 animals 69 experiments) but the number of push per minute fell to 0,57±0,47 making more difficult the interpretation of these results. That's why the experiments, more complicated, requiring both lever activation and signature detection have been realized. The OP, in this case, is 37,76%±9,64 with a number of push which increased back to 3,24±0,7. The comparison with random detection permitted us to be sure that these results are not random (around 25-30 fold more than random analysis). One of the most intriguing features of these experiments is that the area which seems prominently concerned by the execution of the motor task is the cerebellar area and not the central, motor and sensorimotor, areas which would be expected, as in human beings. An aspect of our neuroplasticity study has been to demonstrate that the signature, once identified on cerebellum, can be detected in real-time in other areas of the brain. Our results showed an OP of 15,16%±3,75 in 97 experiments done on 8 rats. These results showed that brain activities correlated with behavioural task identified firstly in cerebellum can be detected in a different area of the brain. The main feature of this report is the demonstration that neural activity continuously recorded at the level of one single cortical electrode can be efficiently used to pilot an effector with one degree of freedom, during experiments up to 1 hour, in a freely moving individual making decisions in a random unsupervised manner. This work is a determining first step towards a larger program aiming at providing a certain level of mobility to young cervical spinal-cord injured patients with tetraplegia.
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Thomas Costecalde. Développement d'interfaces cerveau machine visant à compenser les déficits moteurs chez des patients tétraplégiques. Etudes expérimentales précliniques. Médecine humaine et pathologie. Université de Grenoble, 2012. Français. ⟨NNT : 2012GRENS038⟩. ⟨tel-00870755⟩

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