Neural correlates of visual joint attention studied with fMRI

在本研究中，我们进行了三项研究，以探讨视觉联合注意的神经关联。第一项研究由四种线索范式组成：EYE100 EYE500、ARW100和ARW500。受试者被指示对中央注视的左侧或右侧呈现的目标做出反应，随机且与先例线索的方向无关。提示与目标(SOA)的刺激起始不同步为100毫秒(EYE100和ARW100)或500毫秒(EYE500和ARW500)。在EYE500期间，左侧中央前沟(PRCs)和左侧顶叶内沟(IPS)被激活，与EYE100相反。一般情况下，内源性定向在SOA=500毫秒时的线索效应低于在SOA=100毫秒时的线索效应。结果提示，这些区域可能参与了对非信息性注视引起的反射性定向反应的抑制。在第二项研究中，事件相关功能MA…更多的磁共振成像(FMRI)被用来确定额-顶网络在眼睛注视诱导的反射性定向过程中的功能。眼球100的有效提示激活了左侧的PRC。与ARW100的有效提示相比，激活意义重大。因此，左侧PRCs的功能被指定为跟随眼睛凝视诱导的反射性定向的运动准备。此外，EYE500的无效提示激活了右额中回(MFG)和右顶下小叶(IPL)。这些区域涉及将目标重新定向到已提出目标的实际位置。如上所述，由于内源性定向的提示效应在SOA-500毫秒时减弱，因此可能有助于重新定向到实际目标。在第三项研究中，用食指代替眼睛作为中央线索。和第一个研究一样，我们使用食指(IDX)和箭头(ARW)作为线索，准备了四种线索范式：IDX100、IDX500、ARW100和ARW500。在这项研究中，测量了fMRI扫描的反应时间(RTS)。由于在RTS中发现了性别差异，因此也对fMRI数据进行了性别差异分析。对于RT数据，男性对IDX500的线索效应小于女性。对于男性，除了IDX100，在所有范例中都检测到左额上回(DSFG)和左缘上回(SMG)的激活。本研究结果表明，男性可能成功地忽略了食指的非信息性，并成功地抑制了对反射性定向的反应。本研究表明，1)额顶背侧注意网络可能参与了眼睛注视和食指的反射性定向，2)眼睛注视和食指对反射性定向的抑制可能激活了右侧腹侧额顶区注意网络，3)这些区域的激活可能解释了眼睛凝视和食指的反应时的性别差异。较少

For the present project, three studies were conducted to investigate neural correlates of visual joint attention using fMRI.First study was consisted of four cueing paradigms using a pattern of eyes (EYE) and an arrow (ARW) as a cue : EYE100 EYE500, ARW100, and ARW500. Subjects were instructed to respond to the target that was presented left or right to the central fixation randomly and irrelevantly to the direction of the precedent cue. Stimulus onset asynchrony of the cue to the target (SOA) was 100 (EYE100 and ARW100) or 500 (EYE500 and ARW500) msec. During EYE500, the left precentral sulcus (prCS) and the left intraparietal sulcus (IPS) were activated in contrast to EYE100. Generally, cueing effects of endogenous orienting at SOA=500 msec decrease in comparison with ones at SOA=100 msec. The result suggested that these areas might be involved in inhibition of responses that follow reflexive orienting induced by uninformative eye gaze.In the second study, event-related functional ma … More gnetic resonance imaging (fMRI) was used to specify the function of the fronto-parietal network during reflexive orienting induced by eye gaze. Valid cueing of EYE 100 activated the left prCS. The activation was significant in comparison with valid cueing of ARW100. Therefore, the function of the left prCS was specified as motor preparation that would follow reflexive orienting induced by eye gaze. Moreover, invalid cueing of EYE500 activated the right middle frontal gyrus (MFG) and the right inferior parietal lobule (IPL). These areas are involved in reorienting to the actual position where the target has been presented. Mentioned above, since the cueing effects of endogenous orienting decrease at SOA-500 msec, reorienting to the actual target may be facilitated. The right MFG and IPL activation would be corresponding to reorienting to the actual target.In the third study, an index finger was used as a central cue instead of eyes. As like as the first study, we prepared four cueing paradigms using an index finger (IDX) and an arrow (ARW) as a cue : IDX100, IDX500, ARW100, and ARW500. In this study, the reaction times (RTs) were measured during fMRI scans. Since sex differences were detected in RTs, fMRI data were also analyzed for sex differences. For RT data, the cueing effect of IDX500 shown by males was smaller than one shown by females. For males, activation of the left medial superior frontal gyrus (dSFG) and the left supramarginal gyrus (SMG) was detected during all paradigms except for IDX100. The result suggests that males may succeed in ignoring the uninformative index finger and in inhibition of responses that follow reflexive orienting.Overall, the present project suggests that 1) the dorsal fronto-parietal attention network may be involved in reflexive orienting by eye gaze and index finger, 2) that inhibition of reflexive orienting by eye gaze and index finger may activate the right ventral fronto-parietal attention network, and 3) activation of these areas may explain sex differences of RTs to eye gaze and index finger. Less