Neuroanatomical Signatures of Fluctuation Amplitude and Statistical Bias in Resting-State fMRI

Motivation: Functional MRI (fMRI) is widely used to assess neural activity, yet the effects of diverse cortical input-output architectures on hemodynamic responses remain poorly understood. Goal(s): To investigate how cortical input-output structures relate to fMRI fluctuation amplitude. Approach: We combine cerebral blood volume-weighted (CBVw) fMRI in awake macaques with in vitro neuron density and receptor autoradiography data. Results: Neuron density positively correlates with fMRI amplitude, while regions with higher receptor density show reduced local and global fMRI fluctuations. Impact: Clarifying how brain input-output structures affect fMRI amplitude is crucial for advancing image processing and improving the interpretation of functional connectivity metrics.