Capturing amplitude changes of low-frequency fluctuations in functional magnetic resonance imaging signal: a pilot acupuncture study on NeiGuan (PC6)

This study aims to examine amplitude changes of low-frequency oscillations (fALFF) in the blood-oxygen level-dependent (BOLD) signal associated with acupuncture on NeiGuan (PC6).Ten (10) healthy adults participated in a functional magnetic resonance imaging (i.e., nuclear medicine; fMRI) study. During the brain-imaging procedure, the participants were instructed to lie quietly; they did not perform any cognitive task.Three (3) fMRI scans were conducted for each participant: a first resting-state scan (R1), a stimulating-acupoint scan (AP), and a second resting-state scan (R2) after AP. Individual fALFF maps were calculated for each scan.During R1, consistent with previous studies, the default network regions showed significantly detectable fALFF amplitudes. Acupuncture on PC6 increased fALFF amplitudes within the anterior cingulate cortex (ACC), occipital fusiform gyrus, posterior cingulate cortex, and precuneus (PCC/PCU). In contrast, during R2, fALFF within PCC is still significantly higher than R1 while ACC and cerebellum showed decreased fALFF.These findings imply that stimulating PC6 can change the amplitude of the intrinsic cortical activity of the brain. In particular, a continuous and temporally consistent effect of acupuncture within PCC not the common brain circuit of pain including ACC and cerebellum was observed. Considering the cognitive functions and deficits of the relevant areas in mild cognitive impairment and Alzheimer disease, acupuncture on PC6 could potentially affect both psychiatric and neurological disorders. Thus, stimulating PC6 may be a candidate method for improving cognitive impairment.