INS and Insulin resistance: Taken together, these findings suggest that in the present study, HOMA-IR is a reasonable surrogate marker of central IR, and while characterization of the degree of central insulin resistance was beyond the scope of this study, our finding is consistent with prior demonstrations of a direct effect of central insulin signaling on neural activity in animal models [22, 87] and humans [3, 6, 9, 76, 78, 79, 84, 88, 89].