Hippocampus and episodic learning

The reliability of the hippocampus and surrounding medial-temporal cortices is critical for episodic memory with the hippocampus being posited to support relational or configural related learning. The present event-related fMRI (functional magnetic resonance imaging) study investigated the role of exact medial-temporal lobe structures in learning during relational and item-based processing, as well as the extent to that these structures are engaged in the duration of item-based maintenance of stimuli in working memory. functional magnetic resonance imaging indexed involvement of the hippocampus and underlying cortical regions during performance of two verbal encoding conditions, one which need item-based maintenance of word triplets in working memory and the other that entailed the formation of inter-item associations across the words in each triplet.

Sixteen subjects were scanned using a rapid event-related functional magnetic resonance imaging design although they encountered the item-based and relational processing trials. To examine the correlation among functional magnetic resonance imaging signal in medial-temporal structures during learning and the subject's subsequent ability to remember the stimuli subjects were administered a yes-no recognition memory test following completion of the encoding scans. Through contrast, parahippocampal gyri and entorhinal were differentially engaged during item-based processing, give strong evidence for a functional neuroanatomic distinction between parahippocampal and hippocampal structures. Analysis of the neural correlates of subsequent memory revealed that activation in the bilateral hippocampus was reliably correlated with behavioral measures of effective memory formation only for those stimuli which were encoded in a relational manner