Quantification of Electroacupuncture-Induced Neural Activity by Analysis of Functional Neural Imaging with Monocrystalline Iron Oxide Nanocolloid Enhancement

Abstract

The purpose of this study was to investigate the neural activity of electroacupuncture (EA) quantitatively. The responses of Sprague-Dawley rats' brain to EA on acupoints--Hegu (LI 4) and Neiguan (PC 6)--were detected by monocrystalline iron oxide nanoparticle (MION)-enhanced functional magnetic resonance imaging (MION-fMRI), which is a 1.5 T horizontal spectrometer equipped with a circular polarized extremity coil. During EA at LI 4, neural activities were analyzed by analysis of functional neural images (AFNI). Neural activation was detected at the structures of hypothalamus, thalamus, hippocampus, and the cortex, while neural deactivation existed at the areas adjacent to the activated sites. EA on PC 6 activated the structures of thalamus and the cortex but deactivated the structures of hypothalamus and hippocampus. The brain responses to EA existed in different areas of activation and deactivation despite stimulating the same acupoint. Additionally, distinct brain neuroimages were produced through stimulating different acupoints. This study suggests that fMRI with AFNI is a good approach to quantifying brain activities. This innovative method brings new perspective into the mechanisms of acupuncture.