The accumulation of ß-amyloid (Aß) peptide in Alzheimer plaques has led to a number of studies showing that extracellular Aß can affect synaptic transmission. In this week's Journal, Wang et al. examine the signaling cascades involved in Aß inhibition of NMDA receptor-dependent long-term potentiation (LTP). Their studies point the finger at a cascade involving microglia, inducible nitric oxide synthase (iNOS), and superoxide. The authors propose that peroxynitrite, the product of superoxide and nitric oxide, results from plaque activation of microglia and causes oxidation or nitration of a protein required for LTP induction.
A Dozen Points of Light and the Premotor Cortex: Point-Light Biological Motion Perception Activates Human Premotor Cortex
In primates, motor and premotor areas in the frontal lobe are active not only during action production (movement) but also during action perception (observing the movement of friend or foe). Now Saygin et al. test whether frontal lobe activity also occurs in humans watching "point-light motion," in which movement is defined by a dozen or so lights attached to the joints of an actor. By maximizing fMRI signals, the authors detected frontal lobe activity in response to the points-of-light biological motion. This work suggests that brain areas active in producing movement are also recruited by motion cues alone.
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