Different brain network activations induced by modulation and nonmodulation laser acupuncture

Abstract

The aim of this study is to compare the distinct cerebral activation with continued wave (CW) and 10 Hz-modulated wave (MW) stimulation during low-level laser acupuncture. Functional magnetic resonance imaging (fMRI) studies were performed to investigate the possible mechanism during laser acupuncture stimulation at the left foot's yongquan (K1) acupoint. There are 12 healthy right-handed volunteers for each type of laser stimulation (10-Hz-Modulated wave: 8 males and 4 females; continued wave: 9 males and 3 females). The analysis of multisubjects in this experiment was applied by random-effect (RFX) analysis. In CW groups, significant activations were found within the inferior parietal lobule, the primary somatosensory cortex, and the precuneus of left parietal lobe. Medial and superior frontal gyrus of left frontal lobe were also aroused. In MW groups, significant activations were found within the primary motor cortex and middle temporal gyrus of left hemisphere and bilateral cuneus. Placebo stimulation did not show any activation. Most activation areas were involved in the functions of memory, attention, and self-consciousness. The results showed the cerebral hemodynamic responses of two laser acupuncture stimulation modes and implied that its mechanism was not only based upon afferent sensory information processing, but that it also had the hemodynamic property altered during external stimulation.

Figure 1

Laser acupuncture paradigm design. The paradigm was block design with two conditions (Laser irradiation: A; Laser off: R) and each block was lasted 1-minute (15 scans). Total scan time was 6 minutes (90 scans).

Figure 2

Significant activations for continued wave stimulation included the inferior parietal lobule, the primary somatosensory cortex, and the precuneus of left parietal lobe. Medial and Superior frontal gyrus of left frontal lobe.

Figure 3

Significant activations for modulated wave stimulation included the primary motor cortex and middle temporal gyrus of left hemisphere and bilateral cuneus.

Figure 4

Significant activations for continued wave stimulation versus modulated wave stimulation included the left inferior parietal lobule (IPL) (BA 40) and the left supramarginal gyrus (BA 40).

Figure 5

The same K1 acupoint irradiation with modulated and nonmodulated low-level laser aroused different activations in brain. (CW: continued wave; MW: 10 Hz modulation).