Event Memory, Development

The Neural Substrate of Event Memory

The memory processes of encoding, consolidation, storage, and retrieval rely on a network of brain areas. The structures themselves, as well as the connections between them, have different rates of development. The temporal lobe structures implicated in the encoding and consolidation of memory traces (e.g., hippocampus and surrounding cortices) develop from infancy through the preschool years, with less pronounced changes thereafter. The prefrontal cortex, which is involved in retrieval, undergoes a longer period of development, through adolescence. The time course of development of this temporal cortical network is consistent with known behavioral changes in event memory.

Event Memory in Infancy

In infancy, imitation-based tasks are used to assess event memory. Props are used to produce novel sequences of action that result in a goal or outcome. Infants are encouraged to imitate the sequences immediately, after a delay, or both. Use of this task has revealed age-related changes in the robustness, reliability, and temporal extent of memory throughout infancy. Infants as young as 6 months can reproduce the actions of sequences after 24 hours. By 20 months, the robustness of recall increases such that infants recall the actions of events after as many as 12 months. There also are increases in recall of the temporal order of sequences. After a delay of 1 month between encoding and retrieval, 50% of 9-month-olds, 75% of 13-month-olds, and 100% of 20-month-olds recall sequences in correct temporal order. Over this same space of time, ERPs reveal age-related differences in both encoding and consolidation of memory traces, with older infants exhibiting more robust encoding and more successful consolidation relative to younger infants. Differences in ERPs correlate with variability in behavior.

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