Time-dependent neural activations related to recognition of people's names in emotional and neutral face-name associative learning: an fMRI study.

Previous data have indicated that the left anterior temporal lobe contributes to the retrieval of familiar people's names, and that the extended network including the bilateral anterior temporal lobe plays an important role in the retrieval of newly learned people's names. However, there has been no direct evidence for time-dependent change in brain activation in face-name associations. In addition, previous studies have demonstrated that emotional information such as emotional faces may contribute to the organization of long-lasting episodic memory. In the present study, we investigated the activations related to the recognition of people's names in the context of emotional and neutral face-name associative learning. Before fMRI scanning, subjects learned face-name associations that included emotionally positive and neutral facial expressions. In immediate (5 min later) and delayed (2 weeks later) recognition with fMRI scanning, subjects were presented with studied faces with two names, and were asked to choose the correct associative name learned previously. Recognition-related activations were identified in the anterior part of bilateral temporal lobe for immediate recognition and only in the left temporal lobe for delayed recognition. Further analysis confirmed the time-dependent change in activation of the right anterior temporal lobe. Activation related to the processing of faces with positive expressions were observed in the left periamygdaloid area and temporal pole, although emotional information did not have an influence on task performance in this study. These findings suggest that the neural network involving the bilateral temporal lobe contributes to the retrieval of newly learned people's names, and that the left temporal lobe has a crucial and stable role in retrieval of people's names from faces, whereas the role of the right temporal lobe in retrieval of people's names may decrease with the time course.