https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4087081/
Brain Struct Funct. 2015; 220(2): 1221–1228.
Published online 2013 Dec 1. doi: 10.1007/s00429-013-0679-3
This article has been cited by other articles in PMC.
Abstract
We
have previously hypothesized that the reason why physical activity
increases precursor cell proliferation in adult neurogenesis is that
movement serves as non-specific signal to evoke the alertness required
to meet cognitive demands. Thereby a pool of immature neurons is
generated that are potentially recruitable by subsequent cognitive
stimuli. Along these lines, we here tested whether auditory stimuli
might exert a similar non-specific effect on adult neurogenesis in mice.
We used the standard noise level in the animal facility as baseline and
compared this condition to white noise, pup calls, and silence. In
addition, as patterned auditory stimulus without ethological relevance
to mice we used piano music by Mozart (KV 448). All stimuli were
transposed to the frequency range of C57BL/6 and hearing was objectified
with acoustic evoked potentials. We found that except for white noise
all stimuli, including silence, increased precursor cell proliferation
(assessed 24 h after labeling with bromodeoxyuridine, BrdU). This could
be explained by significant increases in BrdU-labeled Sox2-positive
cells (type-1/2a). But after 7 days, only silence remained associated
with increased numbers of BrdU-labeled cells. Compared to controls at
this stage, exposure to silence had generated significantly increased
numbers of BrdU/NeuN-labeled neurons. Our results indicate that the
unnatural absence of auditory input as well as spectrotemporally rich
albeit ethological irrelevant stimuli activate precursor cells—in the
case of silence also leading to greater numbers of newborn immature
neurons—whereas ambient and unstructured background auditory stimuli do
not.
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