Critical Period - Memory

Memory

Recent studies also support the possibility of a critical period for the development of neurons that mediate memory processing. Experimental evidence supports that notion that young neurons in the adult dentate gyrus have a critical period (about 1–3 weeks after neuronal birth) during which time they are integral to memory formation. Although the exact reasoning behind this observation is indefinite, studies suggest that the functional properties of neurons at this age make them most appropriate for this purpose; these neurons : (1) Remain hyperactive during the formation of memories; (2) are more excitable; and (3) More easily depolarizable due to GABAergic effects. It is also possible that hyperplasticity makes there neurons more useful in memory formation; if these young neurons had more plasticity than adult neurons in the same context, they would be able to be more influential in smaller numbers. The role of these neurons in the adult dentate gyrus in memory processing is further supported by the fact that behavioral experiments have shown that an intact dentate gyrus is integral to hippocampal memory formation. It is speculated that the dentate gyrus acts a relay station for information relating to memory storage. The likelihood of a critical period could change the way we view memory processing because it would ultimately mean that the collection of neurons present is constantly being replenished as new neurons replace old ones. If a critical period does indeed exist this could possibly mean that: (1) Diverse populations of neurons that represent events occurring soon after one another may connect those event temporally in the memory formation and processing; OR (2) These different populations of neurons may distinguish between similar events, independent of temporal position; OR (3) Separate populations may mediate the formation of new memories when the same events occur frequently.