INS and Insulin resistance: Considering that brain response to insulin can be compromised by peripheral insulin resistance [23,25,26], but also by the APOE ɛ4 genotype in an age-dependent manner [24], and that the entorhinal cortex is especially vulnerable to impairments of brain insulin signaling [23], we posit that APOE ε4 carriers and individuals with elevated peripheral insulin resistance are likely to encounter greater challenges in estimating PI when spatial cues are lacking.