Characteristics of Resting-State Functional Connectivity in Older Adults after the PICMOR Intervention Program: A Preliminary Report

Abstract Background: The present study aimed to provide a basis for future research examining neural mechanisms underlying the beneficial effect of an intervention program named Photo-Integrated Conversation Moderated by Robots (PICMOR) on verbal fluency in older adults, which was identified in our previous study. In this preliminary report, we conducted an additional experiment using resting-state functional magnetic resonance imaging (rsfMRI) and investigated the characteristics of resting-state functional connectivity (rsFC) of participants in the intervention group (INT) by comparing with that of participants in the control group (CONT).Methods: The rsfMRI data were acquired from 31 participants in INT and 30 participants in CONT after the randomized control trial. These data were analyzed by a seed-based approach, in which the left inferior and middle frontal gyrus (IFG/MFG) were selected as seed regions and the rsFCs with them were compared between INT and CONT. To interpret the group difference in the rsFCs, we also conducted regression analyses using individual scores of the phonemic verbal fluency test, which were collected before and after the intervention.Results: We found higher rsFC in INT than in CONT between the left IFG and the temporal pole and MFG. The rsFC strength between the left IFG and temporal pole positively correlated with an increased score in the phonemic verbal fluency test through the intervention period. In contrast, we found lower rsFC in INT than in CONT between the left MFG and the posterior cingulate cortex, precuneus, and postcentral gyrus.Conclusions: Along with our previous findings that greater enhancement of the phonemic verbal fluency score through the intervention period was observed in INT than in CONT, the present findings suggest that the beneficial intervention effect is characterized by enhanced rsFC of the left IFG with semantic and executive control-related regions and suppressed rsFC between the left MFG and default mode network.Trial registration: The trial was retrospectively registered at the UMIN Clinical Trials Registry (UMIN000036667) (Date of registration: 7th May, 2019).