A different interpretation of the DIANA fMRI signal.

Abstract

Direct detection of neural activity by functional magnetic resonance imaging (fMRI) has been a longstanding goal in neuroscience. A recent study argued that it is possible to detect neuroelectrical potentials using a specialized fMRI scanning approach the authors termed "direct imaging of neuronal activity" (DIANA). We implemented DIANA in anesthetized rats and measured responses to somatosensory stimulation, reproducing core findings of the original study. We show, however, that neural activity is neither sufficient nor necessary to produce such results. We use a combination of control conditions and simulations to demonstrate that DIANA signals can arise from nonideal aspects of the pulse sequence and specimen that help determine spatiotemporal characteristics of the data. Our analysis emphasizes a need for cautious interpretation and mechanistic evaluation of advanced fMRI techniques.