Tempo-spatial analysis of vision-related acupoint specificity in the occipital lobe using fMRI: an ICA study

Functional acupoint specificity is one of the most debated topics in acupuncture neuroimaging research. Conventional studies investigating vision-related acupoint specificity empirically assume that acupuncture-induced hemodynamic response can be defined a priori and thus concentrate on distinguishing the spatial variations of response patterns across acupoints in the occipital lobe. However, evidence suggests that acupuncture-invoked BOLD signal changes are independent of a priori time shape. Additionally, temporal profiles reflect how a stimulus corresponds with the brain, implying the hemodynamic coherence induced by stimulation. Therefore, temporal information carried in acupuncture-related neural activity may be more crucial to specificity issues. This paper initiates the detection into tempo-spatial dimension and the goal of this study is to detect functional acupoint specificity by uniquely comparing the temporal activities of the occipital lobe among vision-related acupoints (VRA) and a non-acupoint (NAP). We utilized the independent component analysis (ICA) to extract temporal patterns of occipital response by stimulating a VRA, i.e. GB37, and a NAP. As an improvement over previous ones, another VRA, i.e., BL60 was employed to consolidate our findings. Results showed that although all groups showed V1 activity in the occipital lobe, dissociable temporal activities in this region categorized GB37 and NAP (r=0.05, p=0.64). This finding was replicable with regard to BL60 and NAP (r=-0.03, p=0.77). Intriguingly, stimulation at two VRAs induced highly correlated temporal activities (p<0.0001). This study adds positive evidence to the issue of vision-related acupoint specificity. The utilization of ICA and consideration of temporal dynamics may shed light on future studies.