Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
EFFECTS OF EARLY HANDLING ON DEVELOPING AUDITORY MECHANISMS IN THE RAT AS ASSESSED BY THE AUDITORY BRAINSTEM RESPONSE IN ADULTHOOD
Abstract
This study examined the effects of handling of rat pups during either the first or second postnatal week on the latencies and interpeak latencies of the auditory brainstem response as it was recorded in adulthood. Three litters were assigned randomly at birth to one of three conditions: Early Handled during postnatal days 1 through 8 (n = 12 males, 13 females); Late Handled during postnatal days 9 through 16 (n = 10 males, 13 females); or Unhandled during the preweaning period (n = 12 males, 10 females). For the handling treatment, the pups were picked up individually once a day and placed in a plastic container, where they remained for three minutes. They then were returned individually to the home cage. In adulthood, the subjects were anesthetized and their auditory brainstem responses were recorded for monaural and binaural stimulus presentations at 20, 30, 40, and 50 dB nHL. Latencies were measured for waves I, II, and IV, and interpeak latencies were measured for the I-II, II-IV, and I-IV interpeak intervals. The results of this study support the conclusion that the auditory brainstem responses of rats handled during the early postnatal period differ from those of unhandled rats. Early Handled rats were found to have shortened waves II and IV latencies and I-IV interpeak latencies, particularly for the right ear. The ear differences present in Early Handled rats indicate a laterality effect which was consistent across males and females. The shifts in waves II and IV but not wave I suggest that the effect of the treatment was a central rather than peripheral auditory phenomenon. Late Handled females were relatively unaffected by the handling treatment, while Late Handled males had responses which suggested both a laterality effect and a slight cochlear involvement for the left ear. The results of this study indicate that early postnatal experience in rats provides wide-ranging organizational and functional influences on the central nervous system, particularly with respect to laterality. Thus, experiments which assess the auditory brainstem response in rats subsequent to postnatal treatment should be evaluated with caution if early postnatal handling has been employed during the treatment.
Subject Area
Audiology
Recommended Citation
HOWE, SUSAN W, "EFFECTS OF EARLY HANDLING ON DEVELOPING AUDITORY MECHANISMS IN THE RAT AS ASSESSED BY THE AUDITORY BRAINSTEM RESPONSE IN ADULTHOOD" (1983). ETD collection for University of Nebraska-Lincoln. AAI8412306.
https://digitalcommons.unl.edu/dissertations/AAI8412306