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Abstract

Learning that incorporates information from multiple sensory modalities tends to be more effective than learning that is unisensory. For example, auditorily-presented words are remembered better if they are accompanied by congruent pictures. The neural mechanisms underlying benefits of multisensory learning remain unclear; one theory has proposed that auditory learning benefits rely on specific visual cortices. We tested this theory in the context of foreign vocabulary learning. Twenty-two adult learners were trained on novel words and their native language translations over four consecutive days. Words were learned under two conditions. In one condition, participants viewed and performed gestures as words were auditorily-presented, and in another condition, participants viewed static pictures as words were auditorily-presented. Gestures and pictures were congruent with word meanings. Following the vocabulary training, inhibitory and sham transcranial magnetic stimulation (TMS) was applied to the biological motion superior temporal sulcus (bmSTS) as participants listened to the words that they had learned and completed a word translation task. As expected, the application of TMS to the bmSTS slowed translation response times for words that had been learned while performing and viewing gestures but not words learned while viewing pictures. This effect was observed on the day following the learning period, as well as during a second TMS session that occurred 5 months post-learning. We conclude that TMS of a visual cortical region can influence the translation of previously-learned auditory foreign words depending on prior multisensory learning experience, and that multisensory associations influence auditory memory over long timescales.