Modeling Maintenance of Long-Term Potentiation in Clustered Synapses: Long-Term Memory without Bistability

Figure 5

Weight dynamics with imposed LTP of a subset of synapses. (a) A representative time course of a 10-synapse cluster. corresponds to the distribution of Figure 2(a). At days, was set to a high value of 5 for synapses 1–5 and a low value of 0.5 for synapses 6–10. Over 400 days the distinction between strong and weak synapses was largely preserved, with synapses 1–4 remaining at high weights. (b) Dynamics of the potentiated synapses in 10,000 10-synapse clusters. For each cluster, synapses 1–5 were potentiated as in (a); thus dynamics of 5000 synapses are illustrated. Black trace, time course of the average weight of these synapses. Red traces, ±1 standard deviation from average. 700 days after LTP, the average weight remains >1 standard deviation above the steady-state average. (c) Correlation coefficient describing the evolution of synaptic weights during maintenance of the steady-state distribution. For 10,000 synapses in 10-synapse clusters, in the distribution of Figure 2(a), the Pearson correlation coefficient was calculated between the values of at and the values at later times.

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