Exploring neuroendocrine influences on the sensorimotor-association axis in a female and a male individual

Human neuroimaging studies consistently show multimodal patterns of variabilityalong a key principle of macroscale cortical organization-thesensorimotor-association (S-A) axis. However, little is known about day-to-dayfluctuations in functional activity along this axis within an individual,including sex-specific neuroendocrine factors contributing to such transientchanges. We leveraged data from two densely sampled healthy young adults, onefemale and one male, to investigate intra-individual daily variability along theS-A axis, which we computed as our measure of functional cortical organizationby reducing the dimensionality of functional connectivity matrices. Dailyvariability was greatest in temporal limbic and ventral prefrontal regions inboth participants, and was more strongly pronounced in the male subject. Next,we probed local- and system-level effects of steroid hormones and self-reportedperceived stress on functional organization. Beyond shared patterns of effects,our findings revealed subtle and unique associations between neuroendocrinefluctuations and intra-individual variability along the S-A axis in the femaleand male participants. In sum, our study points to neuroendocrine factors aspossible modulators of intra-individual variability in functional brainorganization, highlighting the need for further research in larger samples toassess the sex specificity of these effects.