The effects of aging on lifetime of auditory sensory memory in humans

The amplitude change of cortical responses to repeated stimulation with respect to different interstimulus intervals (ISIs) is considered as an index of sensory memory. To determine the effect of aging on lifetime of auditory sensory memory, N100m responses were recorded in young, middle-aged, and elderly healthy volunteers (n=15 for each group). Trains of 5 successive tones were presented with an inter-train interval of 10 s. In separate sessions, the within-train ISIs were 0.5, 1, 2, 4, and 8 s. The amplitude ratio between N100m responses to the first and fifth stimuli (S5/S1 N100m ratio) within each ISI condition was obtained to reflect the recovery cycle profile. The recovery function time constant (τ) was smaller in the elderly (1.06±0.26 s, p<0.001) and middle-aged (1.70±0.25 s, p=0.009) groups compared with the young group (2.77±0.25 s). In conclusion, the present study suggests an aging-related decrease in lifetime of auditory sensory memory.