Dynamic dot displays reveal material motion network in the human brain

ABSTRACTThere is growing research interest in the neural mechanisms underlying the recognition of material categories and properties. This research field, however, is relatively more recent and limited compared to investigations of the neural mechanisms underlying object and scene category recognition. Motion is particularly important for the perception of non-rigid materials, but the neural basis of non-rigid material motion remains unexplored. Using fMRI, we investigated which brain regions respond preferentially to material motion versus other types of motion. We introduce a new database of stimuli – dynamic dot materials – that are animations of moving dots that induce vivid percepts of various materials in motion, e.g. flapping cloth, liquid waves, wobbling jelly. Control stimuli were scrambled versions of these same animations and rigid three-dimensional rotating dots. Results showed that isolating material motion properties with dynamic dots (in contrast with other kinds of motion) activates a network of cortical regions in both ventral and dorsal visual pathways, including areas normally associated with the processing of surface properties and shape, and extending to somatosensory and premotor cortices. We suggest that such a widespread preference for material motion is due to strong associations between stimulus properties. For example viewing dots moving in a specific pattern not only elicits percepts of material motion; one perceives a flexible, non-rigid shape, identifies the object as a cloth flapping in the wind, infers the object’s weight under gravity, and anticipates how it would feel to reach out and touch the material. These results are a first important step in mapping out the cortical architecture and dynamics in material-related motion processing.

The Fluctuating Lattice Boltzmann

Fluid flow at nanoscopic scales is characterized by the dominance of thermal fluctuations (Brownian motion) versus directed motion. Thus, at variance with Lattice Boltzmann models for macroscopic flows, where statistical fluctuations had to be eliminated as a major cause of inefficiency, at the nanoscale they have to be summoned back. This Chapter illustrates the “nemesis of the fluctuations” and describe the way they have been inserted back within the LB formalism. The result is one of the most active sectors of current Lattice Boltzmann research.

Early active rehabilitation after arthroscopic rotator cuff repair: a prospective randomized pilot study

Objective: To compare two different rehabilitation strategies, primary passive motion versus early isometric loading of the rotator cuff. Design: Prospective randomized controlled observer-blinded pilot study. Setting: Institute of Physical Medicine and Rehabilitation. Subjects: Thirty patients after rotator cuff surgery. Intervention: All participants were randomly assigned to one of the two outpatient treatment groups: primary passive motion versus early isometric loading of the rotator cuff. Both groups were treated for 12 weeks and performed additionally a home exercise program. Main measures: The primary outcome measure for functional assessment was the Constant Murley score. The secondary outcome measures were the Disabilities of the Arm, Shoulder and Hand score (DASH), active range of motion, pain level and strength. Patients were assessed before, 6, 12 and 24 weeks after surgery. Results: Repeatedly measured metric variables were compared by the Quade rank analysis of covariance and revealed substantially better Constant Murley scores in the early activated group at all 3 assessments (6 weeks: 41 [31;45] versus 30 [23;37]; 12 weeks: 68 [56;77] versus 59 [53;62]; 24 weeks: 79 [76;81] versus 66 [62;74]; data as median [25%;75%]). Postoperative changes of Constant score were in favour of the active group with the biggest difference at week 12 (28 [38;12] versus 9 [27;-4]). Maximal pain levels showed clear more reduction 6 and 24 weeks after surgery in the early activated group. Conclusions: This pilot study with early isometric loading of the rotator cuff shows better function and less maximal pain. Further research is warranted to confirm our results.