TELENCEPHALIC AND MIDBRAIN CONTROL OF ACOUSTIC RESPONSIVENESS IN THE GOLDFISH (CARASSIUS-AURATUS)

Goldfish (Carassius auratus) were prepared for recording of brainstem acoustic evoked responses and for prior (>1 sec) delivery of a train o f shocks to the midbrain or telencephalon. Telencephalic stimulation c aused a ca 10% decline in peak acoustic evoked potential (AEP) amplitu de, a small decline after telencephalic ablation recovered after 8-10 min. Midbrain stimulation also caused a decline in peak AEP amplitude of a similar magnitude. Inhibition of acoustic evoked responses occurr ing naturally to non-acoustic priming stimuli, may be mediated by long delayed descending midbrain or telencephalic influences.