I got some citations and references about testing ferrets for deafness as
well as some research with deaf ferrets. Now do I understand this stuff?
Heck no. But I realize that some people will get something out of these.
Maybe if we read them enough we'll understand them. Lol. They are from
an audiological point of view, very proffesional. There is an
audiologist on the FML named Renee who went to the trouble of doing a
search and pulling these out for me and giving them to me. She is
willing to explain this all to me sometime. I better get a depends
(diaper) on my head first though, in case my brain explodes.... or...
implodes.
Citation <1>
Database MEDLINE
Unique Identifier 11694724
Medline Identifier 21550928
Authors King AJ. Kacelnik O. Mrsic-Flogel TD. Schnupp JW. Parsons CH.
Moore DR.
Institution University Laboratory of Physiology, Parks Road, Oxford, OX1
3PT, UK. [log in to unmask]
Title
How plastic is spatial hearing?.
Source
Audiology & Neuro-Otology. 6(4):182-6, 2001 Jul-Aug.
Abstract
The location of a sound source is derived by the auditory system from
spatial cues present in the signals at the two ears. These cues include
interaural timing and level differences, as well as monaural spectral
cues generated by the external ear. The values of these cues vary with
individual differences in the shape and dimensions of the head and
external ears. We have examined the neurophysiological consequences of
these intersubject variations by recording the responses of neurons in
ferret primary auditory cortex to virtual sound sources mimicking the
animal's own ears or those of other ferrets. For most neurons, the
structure of the spatial response fields changed significantly when
acoustic cues measured from another animal were presented. This is
consistent with the finding that humans localize less accurately when
listening to virtual sounds from other subjects. To examine the role of
experience in shaping the ability to localize sound, we have studied the
behavioura!
l consequences of altering binaural cues by chronically plugging one ear.
Ferrets raised and tested with one ear plugged learned to localize as
accurately as control animals, which is consistent with previous findings
that the representation of auditory space in the midbrain can accommodate
abnormal sensory cues during development. Adaptive changes in behaviour
were also observed in adults, particularly if they were provided with
regular practice in the localization task. Together, these findings
suggest that the neural circuits responsible for sound localization can
be recalibrated throughout life. Copyright 2001 S. Karger AG, Basel
Citation <2>
Database MEDLINE
Unique Identifier 7545189
Medline Identifier 95395090
Authors Moore DR. Russell FA. Cathcart NC.
Institution University Laboratory of Physiology, Oxford, United Kingdom.
Title
Lateral superior olive projections to the inferior colliculus in normal
and unilaterally deafened ferrets.
Source
Journal of Comparative Neurology. 357(2):204-16, 1995 Jun 26.
Abstract
We have examined the projection from the lateral superior olive (LSO)
to the inferior colliculus (IC) in the ferret, with particular interest
in the laterality of the projection and in the effects of unilateral
cochlear removal in infancy. Large or small deposits of the retrograde
tracer wheat germ agglutinin-horseradish peroxidase (WGA-HRP) were made
in the IC of anesthetized adult ferrets that either were normally hearing
or had been unilaterally deafened in infancy (P5 or P25). After 2 days,
the ferrets were perfused, and frontal sections of the brainstem were
treated with tetramethyl benzidine. For large deposits of WGA-HRP, equal
numbers of labelled neurons were found evenly spread through both LSOs.
Smaller deposits of WGA-HRP produced four results that contrasted with
previous reports on the cat. First, many more labelled neurons were
found in the contralateral than in the ipsilateral LSO. Second, the
relative number of labelled neurons in each LSO was independent of
whether the deposits were in the ventral or in the dorsal IC. Third, the
total number of labelled LSO neurons was independent of whether the
deposits were in the ventral or in the dorsal IC. Fourth, the proportion
of ipsilateral to contralateral labelled neurons was slightly higher in
the medial LSO than in the lateral LSO. Ventral IC deposits resulted in
more labelled neurons in the medial LSO, and dorsal IC deposits resulted
in more labelled neurons in the lateral LSO, as expected. Neonatal
cochlear removal did not change any of these results. We conclude that,
in the ferret, the organization of the crossed and uncrossed projections
from the LSO to the IC differs from that of the cat, and any similarity
with the optic chiasm is not obvious.
Citation <3>
Database MEDLINE
Unique Identifier 7649837
Medline Identifier 95378060
Authors Harper MS. Wallace MN.
Institution Department of Biomedical Sciences, Marischal College,
University of Aberdeen, Scotland, UK.
Title
Changes in density of brainstem afferents in ferret primary auditory
cortex (AI) during postnatal development.
Source
Journal of Anatomy. 186 ( Pt 2):373-82, 1995 Apr.
Abstract
Histochemical methods were used to assess the distribution of 4
neurotransmitters thought to be involved in cortical plasticity. They
were measured in the primary auditory cortex of the ferret from just
before the onset of hearing. Acetylcholinesterase staining was strongest
in layers I, IV and VI and there was a gradual increase in the amount of
staining from postnatal day (PND) 21 through to adulthood. Serotonin
fibres were located mainly in layers I-III and their density increased
gradually over the same time period. Noradrenergic fibres were sparsely
scattered throughout the cortex but their density and distribution showed
little change over the age range studied. Dopaminergic fibres were
densest in layers V and VI at all ages. However, there was a transient
doubling in their density that started round about the onset of hearing
at PND 28, peaked at PND 35 and had returned to baseline levels by 2 wk
later. This transient peak in density did not occur in the adjacent
suprasylvian gyrus and did not appear to be a general phenomenon. The
local transient increase in dopaminergic fibres implies that they may
have an important role during a short period in auditory cortical
development. This role may involve modifying the cortical circuitry
that is involved in analysing the input from the auditory periphery.
Wolfy
Please visit:
http://www.geocities.com/wolfysluv/
for information on ferret deafness:
http://www.geocities.com/wolfysluv/deaf.html
[Posted in FML issue 3924]
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