Unveiling the neuromechanical mechanisms underlying the synergistic interactions in human sensorimotor system.

Motor synergies are neural organizations of a set of redundant motor effectors that interact with one another to compensate for each other's error and ensure the stabilization of a performance variable. Recent studies have demonstrated that central nervous system synergistically coordinates its numerous motor effectors through Bayesian multi-sensory integration. Deficiency in sensory synergy weakens the synergistic interaction between the motor effectors. Here, we scrutinize the neuromechanical mechanism underlying this phenomenon through spectral analysis and modeling. We validate our model-generated results using experimental data reported in the literature collected from participants performing a finger force production task with and without tactile feedback (manipulated through injection of anesthetic in fingers). Spectral analysis reveals that the error compensation feature of synergies occurs only at low frequencies. Modeling suggests that the neurophysiological structures involving short-latency back-coupling loops similar to the well-known Renshaw cells explain the deterioration of synergy due to sensory deprivation.

[Upper limb mechanical overcharge among health care workers]. / Il rischio da sovraccarico biomeccanico degli arti superiori in ambito sanitario.

In medical circle, the disclosure of recurrent symptomatologies on the upper limbs begins to assume characteristics common to many working classes, raising not few problematic issues regarding the interactions between them and the working environment. In the AOUP of Palermo, some working categories were identified, whose activity implicates the upper limbs for instrument use, as well as repetitious movements (odontologists, ultrasonographers, endoscope technicians). The analysis covered a group of endoscopy technicians, both of the medical area and of the surgical one, the first being middle aged and with working seniority significantly higher than the latter. To these people, a RULA questionnaire was given, partially modified with the addition of some questions finalized at pointing out environmental situations that determine physical stresses on the upper limbs, correlated to the working method, to the number of made tests, to the place where they were made. From the study made, it was found that there is high risk of biomechanical overcharge on the upper limbs in the activity of endoscopy technicians. Thus the necessity of preventive corrective measures geared at avoiding on the one hand insurance claims, and on the other, the pathologies which can limit the working activity.

[Work related diseases: assistance to delivery among obstetricians]. / Patologie lavoro correlate: l'assistenza al parto nel gruppo degli ostetrici.

In the course of Sanitary Surveillance, a high incidence of pathologies of the superior limbs was encountered in a homogeneous group of midwives operating in the AOUP of Palermo. These findings induced the authors' starting a retrospective study aimed at understanding the possibility of correlation between work effected and damage to people, and geared at being able to frame the findings in the ambit of the related to occupational pathologies. It is a fact that the positions taken by midwives in the course of gynecological vaginal delivery, or those necessary to the maneuvers during childbirth, such as the lateral or the simple and/or exaggerated MacRoberts maneuver, require substantial overcharging of the spinal column and a significant engagement of the muscles of the upper limbs. The analysis of the data related to the working load effected in the various years (number of parts/years), highlighted how the group of midwives exposed to a higher risk were those with a longer working life, this in consideration of the great emphasis placed on the upper limbs. It cannot therefore be ruled out that the pathologies encountered in the group of midwives can be framed in the area of occupational related pathologies.