老年人声音诱发闪光错觉的大脑静息态低频振幅

Sound-induced flash illusion in elderly adults:Evidence from low-frequency fluctuation amplitudes in resting-state fMRI

声音诱发闪光错觉(sound-induced flash illusion,SiFI)是一种听觉占主导性的多感觉整合现象,即当视觉闪光伴随不相等数量的听觉声音在100 ms内相继或同时呈现时,个体会错觉性地知觉到视觉闪光的个数与听觉声音的数量相等。本研究分别将老年人群体和年轻人群体的声音诱发闪光错觉量(裂变错觉和融合错觉)与全脑的静息态低频振幅(amplitude of low-frequency fluctuation,ALFF)进行相关分析,考察老年人群体声音诱发闪光错觉效应与大脑静息状态自发活动区域的关系。结果发现,无论是裂变错觉还是融合错觉,老年人声音诱发闪光错觉均增大。对于裂变错觉,老年人的错觉量与内侧前额叶皮层的自发活动呈显著正相关;对于融合错觉,老年人的错觉量与额下回、额中回和颞下回的自发活动呈显著正相关,与枕上回和舌回的自发活动呈现显著的负相关。结果表明,老年人声音诱发闪光错觉量增大的原因与大脑中多个脑区的静息态自发活动存在关系。

Auditory dominance refers to the auditory information in multisensory integration;more priority is given to auditory information,and it is processed in a dominant position.Sound-induced flash illusion(SiFI)is a typical auditory dominance phenomenon,namely,the visual perception of a stimulus for briefly heard voices,qualitatively changing at the same time,resulting in a fission illusion(F1B2)and a fusion illusion(F2B1).Previous studies have shown that elderly adults experience illusions more often than young adults.However,there is not yet a consensus regarding the mechanism when it is investigated using resting fMRI,though resting-state neural activity can reveal the intrinsic functional architecture of the brain(Fox&Raichle,2007).Therefore,the present study aims to investigate how resting-state neural activity(ALFF)is related to SiFIs in elderly adults and will provide important novel insights into the differences in SiFIs between elderly and young adults.We selected 50 elderly adults(ages:50~69 year old,M=61.78,SD=4.17)and 50 young adults(ages:17~27 year old,M=20.86,SD=2.17).The present study was a 2(participants:elderly vs.young adults)×2(flash number:1 vs.2)×3(sound number:0 vs.1 vs 2)mixed design.RS-fMRI data were collected by a magnetic resonance scanner in the participants’natural state of wakefulness and relaxation.The RS-fMRI data were obtained by a Philips 3.0T magnetic resonance scanner,and the images of all participants'resting states were obtained by gradient echoplanar imaging(EPI)and scan parameters as follows:the TR=2000 ms,TE=30 ms,of view(FOV)=220 mm×220 mm,Turn corner=90°,matrix=64×64,Layer number=36,layer thickness=4 mm,with a thick layer of scanning time 400 s.We used the low-frequency amplitude of the resting state of the brain(ALFF)to investigate the correlation between SiFI and spontaneous brain region activity in elderly and young adults to reveal SiFI differences.ALFF results were calculated using DPABI,an RS-fMRI data processing software(Yan et al.,2016).From the perspective of the accuracy results,elderly and young adults both experienced fission and fusion illusions.However,regardless of experiencing a fission illusion or a fusion illusion,the amount of illusion experienced by elderly adults was greater than that experienced by young adults.From the correlation analysis results of ALFF and illusions,there was a significant positive correlation between the F1B2 illusion and spontaneous medial prefrontal cortex(MPFC)activity in elderly adults,and there was a significant negative correlation between the F1B2 illusion and spontaneous activity in the right superior occipital gyrus(SOG)and the left lingual gyrus in young adults.For the F2B1 illusion,there was a significant negative correlation between the F2B1 illusion and spontaneous activity in the right superior occipital gyrus(SOG),the left lingual gyrus(IFG)and the right cerebellum and a significant positive correlation between the F2B1 illusion and the spontaneous activity in the left inferior frontal gyrus(IFG),the right middle frontal gyrus(MFG)and the left inferior temporal gyrus(ITG)in elderly adults.However,there was a significant positive correlation between the F2B1 illusion and spontaneous activity in the left superior frontal gyrus(SFG)in young adults.The present study showed that the increased illusions experienced by elderly adults were related to spontaneous activity during resting states in multiple brain regions.