The hippocampus is particularly important for building associations across stimulus domains

The medial temporal lobe (MTL) is critical for binding together different attributes that together form memory for prior episodes, but whether it is preferentially involved in supporting specific types of associations is a topic of much debate. Some have argued that the MTL, specifically the hippocampus, may be specialized for binding information from different stimulus domains (e.g., linking visual and auditory stimuli). In the current study, we examined the role of the MTL in memory for associations within- vs. across-domains. Patients with either selective hippocampal lesions or more extensive MTL lesions studied pairs of items within the same stimulus domain (i.e., image-image or sound-sound pairs) or across different domains (i.e., image-sound pairs). Associative memory was subsequently tested by having participants discriminate between previously studied and rearranged pairs. Compared to healthy controls, the patients were significantly more impaired in the across-domain condition than the within-domain conditions. Similar deficits were observed for patients with hippocampal lesions and those with more extensive MTL lesions, suggesting that the hippocampus itself is particularly important for binding associations across stimulus domains.