Effect of Exoskeleton-Assisted Rehabilitation Over Prefrontal Cortex in Multiple Sclerosis Patients: A Neuroimaging Pilot Study.

Application of a passive and fully articulated exoskeleton, called Human Body Posturizer (HBP), has been demonstrated to improve mobility, response accuracy and ambulation in multiple sclerosis (MS) patients. By using functional magnetic imaging (fMRI) during a visuomotor discrimination task, we performed a pilot study to evaluate the effect of HBP over the neural correlates of motor and cognitive functions which are typically impaired in MS patients. Specifically, we tested the effect of a 6-week multidisciplinary rehabilitation intervention on two groups of MS patients: a control group who followed a standard physiotherapeutic rehabilitation protocol, and an experimental group who used the HBP during physical exercises in addition to the standard protocol. We found that, after treatment, the experimental group exhibited a significant lower activity (as compared to the control group) in the inferior frontal gyrus. This post-treatment activity reduction can be explained as a retour to a normal range, being the amount of iFg activity observed in the experimental patients very similar to that observed in healthy subjects. These findings indicate that the use of HBP during rehabilitation intervention normalizes the prefrontal activity, mitigating the cortical hyperactivity associated to MS.

One's own country and familiar places in the mind's eye: different topological representations for navigational and non-navigational contents.

Visual mental imagery is a process that draws on different cognitive abilities and is affected by the contents of mental images. Several studies have demonstrated that different brain areas subtend the mental imagery of navigational and non-navigational contents. Here, we set out to determine whether there are distinct representations for navigational and geographical images. Specifically, we used a Spatial Compatibility Task (SCT) to assess the mental representation of a familiar navigational space (the campus), a familiar geographical space (the map of Italy) and familiar objects (the clock). Twenty-one participants judged whether the vertical or the horizontal arrangement of items was correct. We found that distinct representational strategies were preferred to solve different categories on the SCT, namely, the horizontal perspective for the campus and the vertical perspective for the clock and the map of Italy. Furthermore, we found significant effects due to individual differences in the vividness of mental images and in preferences for verbal versus visual strategies, which selectively affect the contents of mental images. Our results suggest that imagining a familiar navigational space is somewhat different from imagining a familiar geographical space.