1. Modulating a song with noradrenaline: Noradrenergic inputs mediate state-dependence of auditory responses in the avian song system
Jessica A. Cardin and Marc F. Schmidt
Norepinephrine (NE)-releasing neurons in the locus ceruleus provide arousal-associated modulation of sensory inputs throughout the brain. Cardin and Schmidt take advantage of the feed-forward organization between forebrain nuclei in the zebra finch auditory system to examine such state-dependent neural processing in vivo. Arousal is known to suppress firing the higher-order song nuclei, NIf and HVC, in response to the bird's own song (BOS). HVC neurons of lightly anesthetized birds, a state of quiescence, responded to BOS recordings, whereas awake birds did not.
2. sAPP-alpha, Transthyretin, and Neuroprotection
Thor D. Stein, Nicholas J. Anders, Charles DeCarli, Sic L. Chan, Mark P. Mattson, and Jeffrey A. Johnson.
The accumulation of beta-amyloid in Alzheimer's disease (AD) is only one of the results of proteolytic cleavage of amyloid precursor protein (APP). Cleavage by beta- and gamma-secretase leads to A-beta production, whereas alpha-secretase cleavage results in a soluble form, sAPP-alpha. This week, Stein et al. examine the apparent neuroprotective role of sAPP-alpha in mice. Using antibody interference and siRNA knockdown techniques, the authors demonstrate, in hippocampal slices and in vivo, that sAPP-alpha provides the mutant mice with the protective armor of increased TTR and IGF-2 expression, thus preventing tau phophorylation and neuronal death. Too bad that sAPP-alpha is not at high levels in Alzheimer's patients.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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