Neural correlates of visual joint attention studied with fMRI

本项目采用功能磁共振成像技术对视觉联合注意的神经关联进行了研究。第一项研究采用四种线索范式：EYE100、EYE500、ARW100和ARW500，以眼睛图案（EYE）和箭头（ARW）为线索。实验对象被要求对出现在中央固定的左侧或右侧的目标随机且与先前提示的方向无关的做出反应。提示到目标的刺激开始异步性（SOA）为100 （EYE100和ARW100）或500 （EYE500和ARW500）毫秒。在EYE500期间，与EYE100相比，左侧中央前沟（prCS）和左侧顶叶内沟（IPS）被激活。一般来说，与SOA=100 msec相比，SOA=500 msec时内生定向的提示效果会降低。结果表明，这些区域可能参与抑制由无信息凝视引起的反射性定向反应。在第二项研究中，使用更多的磁共振成像（fMRI）来明确在眼睛注视诱导的反射定向过程中额顶叶网络的功能。眼100的有效信号激活了左prCS。与ARW100的有效提示相比，这种激活是显著的。因此，左prCS的功能被指定为运动准备，将遵循眼睛注视诱导的反射定向。此外，无效的EYE500提示激活了右侧额叶中回（MFG）和右侧顶叶下小叶（IPL）。这些区域涉及重新定向到目标出现的实际位置。如上所述，由于内源性定向的提示效应在SOA-500 msec时减弱，因此可能有助于重新定向到实际目标。正确的MFG和IPL激活将对应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心线索。与第一项研究一样，我们以食指（IDX）和箭头（ARW）作为提示，准备了四个提示范式：IDX100、IDX500、ARW100和ARW500。在本研究中，反应时间（RTs）测量在fMRI扫描。由于在RTs中检测到性别差异，因此也对fMRI数据进行了性别差异分析。对于RT数据，男性显示的IDX500的提示效应小于女性。对于男性，除了IDX100外，在所有范式中均检测到左侧内侧额上回（dSFG）和左侧边缘上回（SMG）的激活。结果表明，男性可能成功地忽略了不提供信息的食指，并抑制了遵循反射定向的反应。综上所述，本研究提示：1)背侧额顶叶注意网络可能参与眼球注视和食指的反射性定向，2)抑制眼球注视和食指的反射性定向可能激活右侧腹侧额顶叶注意网络，3)这些区域的激活可能解释眼球注视和食指的RTs的性别差异。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