Neural distinctiveness and discriminability in core network representations support associative unitization

Previous work has suggested unitized pairs behave as a single unit and more critically, are processed neurally different than those of associative memories. The current works examines the neural differences between unitization and associative memory using fMRI and multivoxel analyses. Specifically, we examined the differences across face-occupation pairings as a function of whether the pairing was viewed as a person performing the given job (unitized binding) or a person saying they knew someone who had a particular job (associative binding). The results show that at encoding, the angular gyrus can discriminate between unitized and associative target trials. Additionally, during encoding, the medial temporal lobe (hippocampus and perirhinal cortex), frontal parietal regions (angular gyrus and medial frontal gyrus) and visual regions (middle occipital cortex) exhibit distinct neural patterns to recollected unitized and associative targets. Furthermore, the medial frontal gyrus and middle occipital cortex show greater neural similarity for recollected unitized trials than those of recollected associative trials. We conclude that visually unitized pairs may enhance unitization in older adults due to greater similarity of trials within the same condition during the encoding process.