RAPID COMMUNICATION Covert Visual Attention Modulates Face-Specific Activity in the Human Fusiform Gyrus: fMRI Study

Wojciulik, Ewa, Nancy Kanwisher, and Jon Driver. Covert vito biologically significant stimuli such as faces has never sual attention modulates face-specific activity in the human fusibeen tested. form gyrus: an fMRI study. J. Neurophysiol. 79: 1574–1578, The present study tested whether face-specific activity in 1998. Several lines of evidence demonstrate that faces undergo the human fusiform gyrus is reduced for stimuli presented specialized processing within the primate visual system. It has been outside the focus of attention. The fusiform face area (FFA) claimed that dedicated modules for such biologically significant responds to faces in a highly selective manner as compared stimuli operate in a mandatory fashion whenever their triggering with other visual objects (Kanwisher et al. 1997; see also input is presented. However, the possible role of covert attention Allison et al. 1994; Haxby et al. 1991; Puce et al. 1996). to the activating stimulus has never been examined for such cases. Prior imaging data also suggest that the fusiform response to We used functional magnetic resonance imaging to test whether faces can be affected by the task given: it is stronger when face-specific activity in the human fusiform face area (FFA) is modulated by covert attention. The FFA was first identified individsubjects match faces than when they match colors (Clark et al. ually in each subject as the ventral occipitotemporal region that 1998) or locations (Haxby et al. 1994) for the same displays. responded more strongly to visually presented faces than to other However, subjects were not required to maintain fixation in visual objects under passive central viewing. This then served as this previous work, so the findings could be due to foveation the region of interest within which attentional modulation was of the faces only when they must be matched, effectively tested independently, using active tasks and a very different stimuchanging the visual input across tasks. Moreover, color or lus set. Subjects viewed brief displays each comprising two periphlocation matching does not require any analysis of visual eral faces and two peripheral houses (all presented simultaneshape, so previous findings might reflect modulation of shape ously) . They performed a matching task on either the two faces responses in general, rather than of specialized face responses. or the two houses, while maintaining central fixation to equate Our study was designed to reveal whether face-specific fusiretinal stimulation across tasks. Signal intensity was reliably form activity is reduced when faces are presented outside the stronger during face-matching than house matching in both rightand left-hemisphere predefined FFAs. These results show that facefocus of covert attention, with retinal stimulation held conspecific fusiform activity is reduced when stimuli appear outside stant, and with tasks that always required shape comparisons. (vs. inside) the focus of attention. Despite the modular nature of the FFA (i.e., its functional specificity and anatomic localization), M E T H O D S face processing in this region nonetheless depends on voluntary attention. Subjects