Values are expressed as mean ± SD. SR, s. radiatum, SO, s. oriens, SP, s. pyramidale. The number of measurements was n and several measurements were made in each slice. No. of slices = number of mice. In SR and SO, values of α and θ were determined using a traditional analysis of RTI diffusion curves. There was no statistically significant difference between SR and SO values of α and θ (Student's t test, p > 0.05). Values of α and θ were pooled within each genotype (WT: α _{SR + SO} = 0.210, θ _{SR + SO} = 0.465; Has3^−/−: α _{SR + SO} = 0.207, θ _{SR + SO} = 0.473) and used in a multilayer analysis to extract ECS parameters for SP from RTI diffusion curves obtained across three layers (Fig. 7C). For each ECS parameter, SR + SO values and SP values from both genotypes were compared using two-way ANOVA followed by pairwise multiple comparison procedures. For α, factor layer, factor genotype, and their interaction had p < 0.001. For θ, factor layer had p < 0.001. Statistically significant difference between groups (p < 0.05) is marked with asterisks. No statistically significant differences were found for the nonspecific clearance (κ, s⁻¹). In the WT, κ was 0.0086 ± 0.0014, 0.0056 ± 0.0011, 0.0033 ± 0.0025 in SR, SO, and SP, respectively; and κ _{SR + SO} was 0.0070. In Has3^−/− κ was 0.0028 ± 0.0019, 0.0031 ± 0.0006, 0.0079 ± 0.0025 in SR, SO, and SP, respectively; and κ _{SR + SO} was 0.0029.