Molecular Mechanisms Associated with the Benefits of Variable Practice in Motor Learning

Abstract

Variable practice promotes a higher level of motor learning than constant practice. The glutamate receptors, n-methyl-d-aspartate (NMDA) and alfa-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA), have been associated with the changes in motor cortex that occur throughout the process of motor learning. Considering that, it is possible that variable practice is more associated with the NMDA and AMPA receptors than constant practice. This study aimed ao investigating the association between the glutamate receptors, NMDA and AMPA, and constant and variable practice schedules. Seventy-eight male mice practiced the rotarod task in a constant or variable scheduling, in two consecutive days (acquisition phase). Learning tests were performed 24?h and 10?days after the end of the acquisition phase. Variable practice was more associated with the NMDA receptor and had a greater AMPA receptor expression than constant practice. The results suggest that the benefits of variable practice are result of both the greater dependency on the NMDA receptor and the greater AMPA receptor expression.     

Changing Patterns in Methods of Suicide by Race and Sex

ABSTRACT: Suicide rates vary greatly by sex and race but the methods employed by these groups and changes in those methods have been studied neither closely nor systematically across time. In the present study annual official national statistics for specific methods of suicide by sex and racial group from 1923 to 1978 were examined. During this time period shifts were found among groups in the proportions of various suicide methods employed, most notably for women and Asian-Americans. Generally, firearm use increased among nearly all ethnic/racial-sex groups while the use of poisons declined. Although women continue to be more likely than men to kill themselves with solid and liquid poisons, in very recent years firearms have become a more common method. Among Japanese - and Chinese-Americans of both sexes the most frequently employed method has been hanging. Although this is still the case, the proportions have declined over time while the use of firearms has increased. Explanations are offered for the noted changes in method choice with particular attention being given to acculturation and changing societal roles.