Repetition-induced plasticity of motor representations of action sounds.

Action-related sounds are known to increase the excitability of motoneurones within the primary motor cortex (M1), but the role of this auditory input remains unclear. We investigated repetition priming-induced plasticity, which is characteristic of semantic representations, in M1 by applying transcranial magnetic stimulation pulses to the hand area. Motor evoked potentials (MEPs) were larger while subjects were listening to sounds related versus unrelated to manual actions. Repeated exposure to the same manual-action-related sound yielded a significant decrease in MEPs when right, hand area was stimulated; no repetition effect was observed for manual-action-unrelated sounds. The shared repetition priming characteristics suggest that auditory input to the right primary motor cortex is part of auditory semantic representations

Human Neuroscience and the Aging Mind: A New Look at Old Problems

In this article, marking the 65th anniversary of the Journal of Gerontology, we offer a broad-brush overview of the new synthesis between neuroscientific and psychological approaches to cognitive aging. We provide a selective review of brain imaging studies and their relevance to mechanisms of cognitive aging first identified primarily from behavioral measurements. We also examine some new key discoveries, including evidence favoring plasticity and compensation that have emerged specifically from using cognitive neuroscience methods to study healthy aging. We then summarize several recent neurocognitive theories of aging, including our own model--the Scaffolding Theory of Aging and Cognition. We close by discussing some newly emerging trends and future research trajectories for investigating the aging mind and brain. Copyright 2010, Oxford University Press.