Kinematics in the brain: unmasking motor control strategies?

In rhythmical movement performance, our brain has to sustain movement while correcting for biological noise-induced variability. Here, we explored the functional anatomy of brain networks during voluntary rhythmical elbow flexion/extension using kinematic movement regressors in fMRI analysis to verify the interest of method to address motor control in a neurological population. We found the expected systematic activation of the primary sensorimotor network that is suggested to generate the rhythmical movement. By adding the kinematic regressors to the model, we demonstrated the potential involvement of cerebellar-frontal circuits as a function of the irregularity of the variability of the movement and the primary sensory cortex in relation to the trajectory length during task execution. We suggested that different functional brain networks were related to two different aspects of rhythmical performance: rhythmicity and error control. Concerning the latter, the partitioning between more automatic control involving cerebellar-frontal circuits versus less automatic control involving the sensory cortex seemed thereby crucial for optimal performance. Our results highlight the potential of using co-registered fine-grained kinematics and fMRI measures to interpret functional MRI activations and to potentially unmask the organisation of neural correlates during motor control.

[Indications for brain scan in patients presenting benign cranial injury]. / Indications du scanner cérébral chez les patients présentant un traumatisme crânien bénin.

OBJECTIVE: Validate the clinical criteria, which, when absent, would make it safe to bypass CT scan examination in mild cranial injuries. MATERIAL: and methods. Prospective study including 285 patients with mild cranial injury with a Glasgow score of 15, a normal clinical examination but transitory loss of consciousness or suspected transitory loss of consciousness. The following clinical parameters were systematically reviewed: history of stroke; post-injury headache; post-injury vomiting; alcohol, medication, or drug intoxication; clinical signs of cervico-cranio-facial injury; post-injury convulsions; or coagulation impairment. Systematic CT exploration looked for cranial, encephalic, and facial lesions and individualized the lesions requiring neurosurgical or maxillofacial treatment. RESULTS: Of the patients studied, 7% presented a cranioencephalic lesion and 7% a facial bone lesion. Neurosurgical intervention was necessary in 0.4% of the patients and maxillofacial surgery in 2.5%. Patients with a positive CT all had at least one clinical risk factor and patients with cranioencephalic lesions had at least two risk factors present. Had patients with no risk factors not been scanned, 15% of the patients would not have had the CT procedure. CONCLUSION: Selecting CT indications in cases of mild cranial injury with loss of consciousness using a simple and validated evaluation can save 15% of CT procedures without missing any cranial, encephalic, or facial lesions.