The insulating layers of myelin membrane wrapped around axons by oligodendrocytes are essential for the rapid conduction of nerve impulses in the central nervous system. To fulfill this function as an electrical insulator, myelin requires a unique lipid and protein composition. Here we show that oligodendrocytes employ a barrier that functions as a physical filter to generate the lipid-rich myelin-membrane sheets. Myelin basic protein (MBP) forms this molecular sieve and restricts the diffusion of proteins with large cytoplasmic domains into myelin. The barrier is generated from MBP molecules that line the entire sheet and is, thus, intimately intertwined with the biogenesis of the polarized cell surface. This system might have evolved in oligodendrocytes in order to generate an anisotropic membrane organization that facilitates the assembly of highly insulating lipid-rich membranes.

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The aim of the present proof-of-concept study was to test a novel cognitive bias modification (CBM) programme in an analogue sample of people with subclinical bulimic eating disorder (ED) psychopathology. Thirty participants with high levels of trait food craving were trained to make avoidance movements in response to visual food stimuli in an implicit learning paradigm. The intervention comprised ten 15-minute sessions over a 5-week course. At baseline, participants showed approach and attentional biases towards high-caloric palatable food that were both significantly reduced and turned into avoidance biases after the training. Participants also reported pronounced reductions in both trait and cue-elicited food craving and in ED symptoms as well. The overall evaluation of the training by the participants was positive. The specific CBM programme tested in this pilot trial promises to be an effective and feasible way to alter automatic action tendencies towards food in people suffering from bulimic ED psychopathology.