EEG Correlates of Auditory Short-Term Memory and Dissimilarity Perception in Young and Older Adults.

Understanding the neural correlates of short-term memory is crucial, particularly in the context of aging. In this electroencephalography (EEG) study, we investigated the impact of aging on the brain activity underlying short-term memory and perception of dissimilarity of auditory sequences. Fifty-four participants were divided into two groups: (i) 29 young adults (20-30 years old) and (ii) 25 older adults (60-80 years old). We used a variation of the same/different task employing pairs of tone sequences and asking participants to rate the degree of dissimilarity of the second sequence in comparison to the first one. Sequences could be either identical (same), totally different, or with transposed tones. Behavioral results showed a lower level of perceived dissimilarity in different sequences in older compared to young adults. The memory task induced a fronto-central negative slow wave (NSW) that was significantly higher in the 20-30 group for all three conditions. NSW was higher in the same than in the different and transposed conditions but only in young adults. In transposed sequences, NSW amplitude was modulated by the perception of dissimilarity. The P50 component to first sound of the second sequence was significantly higher in older adults. The N1 was more negative in the same than in the different and transposed conditions. The P2 was higher in the same than in the transposed condition.