Cerebello-thalamo-cerebral diaschisis: a case report.

This reports positron emission tomography and [18F]fluorodeoxyglucose (PET-FDG) in a 69-year-old woman who underwent resection of the left cerebellar hemisphere for an acoustic neurinoma 17 years earlier. Functional impairment in cerebral cortical and subcortical structures was evaluated by studying the level of glucose metabolic activity at rest. Relative glucose metabolism was reduced in the prefrontal cortex contralateral to the cerebellar lesion. Contralateral thalamic metabolism was reduced significantly. The results suggest that this phenomenon of "crossed cerebello-thalamo-cerebral diaschisis" is related to a functional depression of the cerebello-thalamo-cortical pathway.

The effects of short periods of immobilization on the hamster circadian clock.

Recent findings indicate that stimuli which induce an acute increase in locomotor activity can induce phase shifts in the circadian clock of hamsters. Support for the actual role of the acute increase in activity in the mediation of these phase shifts is provided by the observation that immobilization can totally block phase shifts in the activity rhythm that are normally induced in response to exposure to two of these stimuli, either a pulse of darkness or an injection of a benzodiazepine. In order to further examine the effects of immobilization on the circadian system of hamsters, 3 studies were carried out. In a first study, the effects of a 3-h period of immobilization procedure on the phase of the free running circadian rhythm of locomotor activity were tested at 8 different circadian times. Immobilization during the highly active part of the animal's activity cycle resulted in phase delays in the activity rhythm, while immobilization at other circadian times had little or no effect on the circadian time-keeping system. In two other studies, we reported that immobilization had no effect on phase shifts normally induced by 3-h pulses of light or injections of the protein synthesis inhibitor, cycloheximide, two stimuli that are clearly not associated with an increase in locomotor activity in hamsters. Thus, the ability of immobilization to block stimulus-induced phase shifts in the circadian clock appears to be specific to those stimuli that induce an acute increase in locomotor activity.(ABSTRACT TRUNCATED AT 250 WORDS)