Frank,
You might be interested in checking out one of my articles that just came
out in Nature (Prakash, Cohen-Cory, and Frostig, June 20, 1996, p.
702-706). I topically applied NGF to the somatosensory cortex of
anesthetized rats and imaged the activity of neurons evoked by whisker
stimulation. We found that NGF rapidly (within 20 min), but transiently
(returning to baseline within 1 hour) enhanced the cortical response to
whisker stimulation.
This may not be the "negative" effect you are seeking, but the broader
implications remain to be shown--if it enhances evoked responses in the
somatosensory cortex what else might it enhance? pain sensations (i.e. a
central mechanism for hyperalgesia)? agitation? other sensory or motor or
hypothalamic pathways?
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-Neal Prakash
Department of Psychobiology, College of Medicine
http://meded.med.uci.edu/~nprakash/neal.html
lab:714-824-5031
fax:714-824-2447