[Event-related potentials and auditory sensory memory].

OBJECTIVE

Deficits in auditory short-term memory are thought to underlie developmental language disorders and dyslexia. There is, however, a lack of systematic studies of short-term memory in children at a young age. The aim of this study was to probe the duration of auditory sensory memory using objective methods in young children.

METHOD: 37 two-year-old and 52 six-year-old normally developing children were included in the study. Event-related potentials (ERPs) were elicited in a passive auditory oddball paradigm with variable interstimulus intervals (ISIs of 0.5-5 s, depending on the subgroup).

RESULTS

For shorter ISIs, a prominent mismatch negativity (MMN) and late discriminative negativity (LDN) were found, while a distinct P3a occurred particularly for longer ISIs. Statistical significance was proven for the dependence of MMN and LDN amplitudes on the ISI. The change in the structure of the ERP components occurred at a longer ISI for the six-year-olds than for the 2-year-olds.

CONCLUSIONS

The points where MMN and LDN disappear with increasing ISI suggest that the duration of auditory sensory memory lies between 1 and 2 s in two-year-old children and between 3 and 5 s in six-year-olds. The occurrence of a P3a beyond the point where MMN and LDN can no longer be elicited, however, provides evidence that several different mechanisms with different durations of memory representations are involved in short-term storage of auditory information.