Neural correlates of visual joint attention studied with fMRI

本研究采用fMRI技术对视觉联合注意的神经机制进行了研究，第一个研究采用四种提示范式，分别为EYE 100、EYE 500、ARW 100和ARW 500，其中EYE 100和ARW 500是以眼睛和箭头为线索的。受试者被指示对中央注视点左侧或右侧随机呈现的目标做出反应，并且与先前提示的方向无关。提示对靶点的刺激起始时间（SOA）为100（EYE 100和ARW 100）或500（EYE 500和ARW 500）毫秒。在EYE 500期间，与EYE 100相比，左侧中央前沟（prCS）和左侧顶内沟（IPS）被激活。一般来说，在SOA=500毫秒的内源性定向的线索效应减少相比，在SOA=100毫秒。结果表明，这些脑区可能参与了对无信息注视引起的反射性定向反应的抑制。 ...更多信息 磁共振成像（fMRI）被用来详细说明在由眼睛注视引起的反射定向过程中额顶叶网络的功能。EYE 100的有效提示激活了左侧prCS。与ARW 100的有效提示相比，激活是显著的。因此，左侧prCS的功能被指定为运动准备，其将遵循由眼睛注视引起的反射定向。此外，EYE 500的无效提示激活了右侧额中回（MFG）和右侧顶下小叶（IPL）。这些区域涉及重新定向到目标已经呈现的实际位置。如上所述，由于内源性定向的提示效应在SOA-500毫秒时降低，因此可以促进重新定向到实际目标。右侧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，食指代替眼睛作为中心线索。与第一个研究一样，我们准备了四个使用食指（IDX）和箭头（ARW）作为线索的线索范式：IDX 100，IDX 500，ARW 100和ARW 500。在这项研究中，在fMRI扫描过程中测量反应时间（RT）。由于RTs检测到性别差异，因此还分析了fMRI数据的性别差异。对于RT数据，IDX 500的提示效应显示男性小于女性。对于雄性动物，除IDX 100外，在所有范式中均检测到左侧内侧上级额回（dSFG）和左侧缘上回（SMG）的激活。结果表明，男性可能成功地忽略了无信息的食指，并成功地抑制了反射性定向后的反应。总体而言，本项目表明：1）背侧额顶注意网络可能参与了由眼睛注视和食指引起的反射性定向，2）抑制由眼睛注视和食指引起的反射性定向可能激活了右腹侧额顶注意网络，（3）这些区域的激活可以解释注视和食指反应阈的性别差异。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