Auditory brainstem of the ferret: early cessation of developmental sensitivity of neurons in the cochlear nucleus to removal of the cochlea.

摘要: The role of primary afferent innervation in the maintenance neurons mammalian auditory system was assessed by performing unilateral removals cochlea neonatal and mature ferrets known birth dates. Removals were performed under steroid anesthesia resulted complete destruction organ Corti loss at least 80% type I spiral ganglion neurons. Four main age groups [postnatal days (P)5, P24, P90, P180] used. Additional animals received no surgery, partial removals, or older ages. Three months after cochlear removal reanesthetized perfused. brainstem temporal bones wax-embedded, frontally sectioned, Nissl-stained. Sections right left nuclei compared quantitatively. Removal P5 more than 50% large (nongranular) throughout ipsilateral nucleus. Lesions ages did not produce any neuron loss. size remaining reduced 10-15% all groups. Partial lesions produced a graded response nucleus that related to extent lesion. developmental sensitive period for effects on ferret is therefore over before (P28-P30) which animal begins hear. present result differs markedly from chicken, persists 2 onset hearing.