Abstract
Attention has been shown to modulate the fMRI adaptation response to repeated faces in the fusiform regions (Yi et al., 2006). Specifically, when attention is diverted away from faces, the adaptation response is reduced. This study demonstrates that when the task requirement is to discriminate between face-pairs, the adaptation response is also reduced even though subjects were attending to faces. In this event-related fMRI adaptation study, 20 young subjects viewed serially presented face-pairs that were identical (repetition of the same face), moderately different (second face was morphed with 40% of prior face), or completely different (faces from two individuals). Subjects underwent two sessions involving different task instructions. The first task required subjects to identify a previously shown target face that was intermittently presented during the experimental session. This task maintained subjects' attention to the face identity, but made the face-repetition irrelevant to the task. The second task required subjects to make same-different judgments for each face-pair, thus face-repetition became task-relevant. During the target face detection task, the fusiform regions showed adaptation during the exact-repetition condition and the moderately-different condition relative to the completely-different condition as expected. During the face discrimination task, however, adaptation magnitude in this region was significantly reduced. This suggests that when the task requires, subjects are able to suppress the adaptation responses to faces in the fusiform regions, and to maintain face representation for efficient discrimination. We also found that the task-related decrease of the adaptation responses in the fusiform area was linked to face discrimination performance.
This work is support by NIA Grant AG006265-21.