Abstract 1482, Date 1:00 PM, Sunday February 22, 2004 (24 hours) Session D9:Auditory Midbrain and Cortex: Learning and Plasticity
Contributions of Experience and Acetylcholine to Environmental Plasticity in Auditory Cortex
Cherie R. Percaccio, Autumn L. Pruette, Shilpa T. Mistry, Eric J. Kildebeck, Ye Ting H. Chen, Michael P. Kilgard
We have previously demonstrated that cortical responses of rats housed in an enriched environment are twice the amplitude of responses from standard housed rats (Percaccio et. al. ARO 2002). The current experiments were designed to investigate the contributions of exercise, social stimulation, passive sound exposure, and cholinergic modulation on the auditory evoked potential plasticity observed in the earlier study. Responses to noise bursts and tones were recorded 1-2 times a week for a period of months. To investigate the influence of acetylcholine on enrichment-induced plasticity, animals were injected with a highly specific cholinergic immunotoxin (or an inactive control), and housed in the enriched environment. Otherwise, animals were housed in environments designed to isolate particular components of enrichment. Preliminary results indicate that neither social nor exercise enrichment alone are significantly different from animals housed in a standard environment. These groups are significantly different from auditory exposure alone and animals housed in an enriched environment, which are not different from each other. Rats with cholinergic lesions are not significantly different from animals with an intact nucleus basalis regardless of environment. In all groups, environmental plasticity was more readily observable using tones that do not completely saturate auditory cortex responses. These results indicate that acetylcholine is not necessary for environmental plasticity, and auditory exposure alone is sufficient to cause substantial experience dependent plasticity.