Article,
Exposure to low frequency noise during rearing induces spongiform lesions in gerbil cochlear nucleus: High frequency exposure does not
Hearing Research, (1994)
Abstract
Spongiform lesions of the gerbil cochlear nucleus are reduced in number
and extent by rearing in acoustic isolation compared with rearing
while exposed to normal colony low-frequency background noise. This
study tested whether rearing under exposure to noise bands of moderate
intensity would increase the number and extent of cochlear nucleus
spongiform lesions. Gerbils were reared from weaning to young adulthood
in acoustic isolation chambers while continually exposed to moderately
intense bands of either high frequency or low frequency noise. Exposure
to low frequency noise resulted in lesion number and area densities
that were more than twice those seen in gerbils exposed to high frequency
noise. Lesion extent in the low frequency group was similar to that
in colony-reared gerbils; lesion extent in the high frequency group
was similar to gerbils reared in acoustic isolation. Comparisons
within the posterior ventral cochlear nucleus revealed that the differences
in lesion extent were most pronounced in the middle and dorsal-medial
portions, the regions that are most responsive to middle and high
frequencies. These finding suggest that the regional restriction
of spongiform lesions within the cochlear nucleus does not have a
tonotopic basis.
