The Journal of Neuroscience, December 1, 1999, 19(23):10554-10561
Deafening Alters Neuron Turnover within the Telencephalic Motor
Pathway for Song Control in Adult Zebra Finches
Niangui
Wang,
Rina
Aviram, and
John R.
Kirn
Department of Biology, Wesleyan University, Middletown, Connecticut
06459
In the telencephalon of adult songbirds, projection neurons are
lost and replaced within the efferent pathway controlling learned vocal
behavior. We examined the potential role of auditory experience in
regulating the addition and long-term survival of vocal control neurons
in adult male zebra finches. Deafened and control birds were injected
with the cell birth marker [3H]thymidine
and then killed 1 or 4 months later. At the 1 month survival time, the
number of [3H]-labeled neurons present in the high
vocal center (HVC) was 70% lower in deafened birds compared with
controls. This was true for all [3H]-labeled HVC
neurons, as well as the subset that projected to the robust nucleus of
the archistriatum. Over the next 3 months, two-thirds of the
[3H]-labeled HVC neurons in control birds were
lost, presumably through cell death. Surprisingly, deafened birds
showed no loss over this interval. The total number of HVC neurons did
not differ between control and deafened birds at either survival time.
Nuclear diameters of [3H]-labeled HVC neurons
decreased with cell age in both control and deafened birds, a process
that may relate to the eventual death and replacement of these cells.
These results suggest that experience influences the addition and also
the longer-term fate of neurons formed in adulthood. We propose that
auditory deprivation decreases the incorporation of new neurons and
prolongs their life span. Alterations in the neuronal replacement cycle
may relate to the gradual deterioration in song that occurs after
deafening in adult zebra finches.
Key words:
adult neurogenesis; auditory experience; nuclear size; neuronal life span; zebra finch; high vocal center; [3H]thymidine autoradiography
Copyright © 1999 Society for Neuroscience 0270-6474/99/192310554-08$05.00/0
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