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]