The neural basis of the effects of aging on temporal processing in the rat primary auditory cortex

grantor: University of TorontoOne complaint among the elderly is a difficulty in understanding speech. One factor that may contribute to this, is an age-related deterioration in temporal processing speed, manifested as a decreased ability to process dynamic aspects of speech such as formant transitions. The goal of this study was to explore the neural basis of the effects of aging on auditory temporal processing. A useful stimulus for this investigation is the frequency-modulated (FM) sweep which resembles formant transitions. Extracellular single unit responses were recorded in the auditory cortex (AI) of young and old male Long Evans hooded rats. Tone bursts were presented followed by linear FM sweeps (from low to high and from high to low) at different rates of modulation. Results show that the majority of cells recorded from young rats responded best to fast FM sweeps while those from old rats preferred slower speeds. This suggests a neurophysiological basis for the difference in cortical temporal processing speed between young and old rats for dynamic stimuli.M.Sc