Figure 2.

Neuronal Activity Properties of a Single Associative Memory

(A) Size of the neuronal population encoding an associative memory: percentage of excitatory neurons with average ff > 10 Hz upon S1 presentation, measured before (Pre) and after training (recall), under the three PRP conditions.

(B) Average firing rate of the coding neurons before (Pre) and after training (recall), upon S1 presentation, under the three conditions.

(C) Sparseness of the entire neuronal population measured by the Treves-Rolls metric, before (Pre) and after training (recall), upon S1 presentation, under the three conditions.

(D) Conceptual models of population responses before and after learning for somatic, local, and combined (S&L) PRP conditions. The neuronal memory engram denoted by the coding cells (blue circles filled with yellow-orange colors) is similar in size under conditions of somatic or dendritic (local) PRPs and slightly larger if PRPs are available throughout the neuron (S&L). However, it is highest in contrast (differences in color of coding versus responsive but non-coding cells), under somatic, followed by S&L and local PRP conditions.

Graphs show average ± SEM of 10 trials. ^∗∗p < 0.01, one-way ANOVA followed by Bonferroni post-test. See also Figures S2, S4, and S5.