Visual fixations to objects reflect configural processing in the perirhinal cortex among younger and older adults

Poster Session C - Sunday, April 14, 2024, 5:00 – 7:00 pm EDT, Sheraton Hall ABC

Natalia Ladyka-Wojcik¹, Rosanna K. Olsen^1,2, Jennifer D. Ryan^1,2, Morgan D. Barense^1,2; ¹University of Toronto, ²Rotman Research Institute (Baycrest Health Sciences)

Object recognition relies on the ability to bind the configural arrangement between object features into mental representations. Evidence in amnesic patients with medial temporal lobe (MTL) damage points to the perirhinal cortex (PRC) as a key region supporting configural object processing. Recently, modelling of functional connections of the PRC suggests that it interfaces with the brain's oculomotor (i.e., eye movement) control system. However, little work has explored the relationship between visual fixations to configural objects and functional activation of the PRC. In our study, younger and older participants (N = 95) completed a configural object processing task while undergoing functional imaging (fMRI) and while their fixations were tracked. Within each experimental block, participants saw five repetitions of three computer-generated objects comprised of distinct upper and lower halves. On the sixth and seventh repetitions, we showed participants three possible configurations: old objects from prior repetitions in the block; reconfigured objects in which the two halves had been presented as parts of different objects in the block; and novel objects in which both halves were new. Manually segmented masks constrained our functional analyses of the MTL. Both older and younger adults showed novelty preference in their fixations, but only younger adults showed evidence of object familiarity in average fixation durations. The PRC was the only MTL region that showed significantly different activation between age groups for old, reconfigured, and novel objects. Finally, our results provide evidence for the relationship between PRC activation and configural novelty reflected in eye movements, mediated by age.

Topic Area: LONG-TERM MEMORY: Episodic