Beat synchronization across the lifespan: intersection of development and musical experience

Rhythmic entrainment, or beat synchronization, provides an opportunity to understand how multiple systems operate together to integrate sensory-motor information. Also, synchronization is an essential component of musical performance that may be enhanced through musical training. Investigations of rhythmic entrainment have revealed a developmental trajectory across the lifespan, showing synchronization improves with age and musical experience. Here, we explore the development and maintenance of synchronization in childhood through older adulthood in a large cohort of participants (N = 145), and also ask how it may be altered by musical experience. We employed a uniform assessment of beat synchronization for all participants and compared performance developmentally and between individuals with and without musical experience. We show that the ability to consistently tap along to a beat improves with age into adulthood, yet in older adulthood tapping performance becomes more variable. Also, from childhood into young adulthood, individuals are able to tap increasingly close to the beat (i.e., asynchronies decline with age), however, this trend reverses from younger into older adulthood. There is a positive association between proportion of life spent playing music and tapping performance, which suggests a link between musical experience and auditory-motor integration. These results are broadly consistent with previous investigations into the development of beat synchronization across the lifespan, and thus complement existing studies and present new insights offered by a different, large cross-sectional sample

Preparation and properties of human erythrocyte ghosts

Ghosts are post-hemolytic residues of red blood cells. It is generally assumed that these residues are devoid of intracellular structure and consist primarily of the cell membrane. Hence ghosts are widely used in the study of composition, structure, and function of the red blood cell membrane. There are possibly as many different types of ghosts as there are ways of hemolyzing red blood cells a. The present review on the preparation and properties of red blood cell ghosts is confined to ghosts made by hypotonic hemolysis. These ghosts have a composition which, in many respects, is similar to or even identical with that of the membrane of the intact cell. Hence, "hypotonic ghosts" have been more intensely investigated than those prepared by other techniques. In spite of the fact that in all preparations of hypotonic ghosts hemolysis is induced by the mechanical stress brought about by an osmotic pressure difference, the properties of the final product still depend on the precise conditions existing at the instant of the disruption of the membrane and on the treatment of the resulting ghosts thereafter. The discussion of the effects of such modifying factors constitutes the bulk of this paper