Figure 8.

DNMS acquisition significantly correlates with synaptic indices, in particular thin spine head volume. A, The scatter plot of DNMS acquisition (trials required to reach 90% accuracy with a 10 s delay) versus EM synaptic density shows a moderate though significant inverse correlation, meaning that higher synaptic density is predictive of faster learning. B, This inverse correlation is somewhat strengthened when the density of only thin spines is used on the subset of animals for which spine density analysis was performed (r = −0.58 in A and r = −0.69 in B; p < 0.05 for both). C, DNMS acquisition correlates most strongly with the mean volume of thin spines, where bigger volumes are predictive of slower learning. D, In contrast, no correlation is seen between learning of the DNMS task and mean mushroom head volume. r, Pearson correlation coefficient.