19 September 2008. Experimental evidence and plain common sense
tell us that neurons lose activity in Alzheimer disease, but a
new study surprisingly suggests that under certain conditions,
neurons may become more active. This work comes from Marc Aurel
Busche and colleagues at the Technische Universitaet,
Maximilians-Universitaet, and the Center for Integrated Protein
Science (all in Munich, Germany), as well as Novartis Institutes
for Biomedical Research in Basel, Switzerland, and is published
in today’s Science. Using in vivo calcium-imaging, the
scientists examine layer 2/3 cortical neurons in transgenic mice
that overproduce both mutant amyloid precursor protein and
presenilin (APP23xPS45 mice). The investigators describe a
decrease in activity in about one-third of layer 2/3 neurons,
but an increase in the activity of 21 percent of neurons in the
same area, as measured by spontaneous calcium bursts. What is
most notable is that the hyperactive neurons were found directly
in the vicinity of amyloid plaqu