The pathophysiology of restricted repetitive behavior

Restricted, repetitive behaviors (RRBs) are heterogeneous ranging from stereotypic body movements to rituals to restricted interests. RRBs are most strongly associated with autism but occur in a number of other clinical disorders as well as in typical development. There does not seem to be a category of RRB that is unique or specific to autism and RRB does not seem to be robustly correlated with specific cognitive, sensory or motor abnormalities in autism. Despite its clinical significance, little is known about the pathophysiology of RRB. Both clinical and animal models studies link repetitive behaviors to genetic mutations and a number of specific genetic syndromes have RRBs as part of the clinical phenotype. Genetic risk factors may interact with experiential factors resulting in the extremes in repetitive behavior phenotypic expression that characterize autism. Few studies of individuals with autism have correlated MRI findings and RRBs and no attempt has been made to associate RRB and post-mortem tissue findings. Available clinical and animal models data indicate functional and structural alterations in cortical-basal ganglia circuitry in the expression of RRB, however. Our own studies point to reduced activity of the indirect basal ganglia pathway being associated with high levels of repetitive behavior in an animal model. These findings, if generalizable, suggest specific therapeutic targets. These, and perhaps other, perturbations to cortical basal ganglia circuitry are mediated by specific molecular mechanisms (e.g., altered gene expression) that result in long-term, experience-dependent neuroadaptations that initiate and maintain repetitive behavior. A great deal more research is needed to uncover such mechanisms. Work in areas such as substance abuse, OCD, Tourette syndrome, Parkinson’s disease, and dementias promise to provide findings critical for identifying neurobiological mechanisms relevant to RRB in autism. Moreover, basic research in areas such as birdsong, habit formation, and procedural learning may provide additional, much needed clues. Understanding the pathophysioloy of repetitive behavior will be critical to identifying novel therapeutic targets and strategies for individuals with autism

Радиационная стойкость нитевидных кристаллов SiGe, используемых для сенсоров физических величин

Приведены результаты исследования влияния облучения γ-квантами дозами до 1·10¹⁸ см⁻² и магнитного поля с индукцией до 14 Тл на электропроводность нитевидных кристаллов Si1-xGex в интервале температуры 4,2-300 К.Вивчено вплив опромінення γ-квантами (випромінювання Co⁶⁰) з дозами до 1·10¹⁸ см⁻² та магнітного поля з індукцією до 14 Тл на електропровідність ниткоподібних кристалів Si1-xGex (х = 0,03) з питомим опором 0,08,0,025 Ом·см в інтервалі температур 4,2 .300 К. Встановлено, що опір кристалів слабо змінюється в процесі опромінення дозами до 2·10¹⁷ см⁻², в той же час спостерігаються істотні зміни магнітоопору. На основі проведених досліджень запропоновано умови створення радіаційно стійких сенсорів деформації, дієздатних в умовах сильних магнітних полів.An influence of γ-irradiation (Co⁶⁰) with doze up to 1·10¹⁸ cm⁻² and magnetic field with induction up to 14 T on conduction of Si1-xGex (x = 0,03) whisker crystals with resistivity of 0,08-0,025 Ohm·cm in temperature range 4,2-300 K have been studied. It is shown that whisker crystals resistance faintly varies under irradiation with doze 2·10¹⁷ cm⁻², while their magnetoresistance substantially changes. The strain sensors stable to irradiation action operating in high magnetic fields on the base of the whiskers have been designed