Virtual fMRI brown bag: April 24

Please join us for a talk given by Serra Favila, a postdoctoral fellow at Columbia University.

Time: 12:00-1:00pm

Place: Zoom - details tbd

Quantifying long-term memory reactivation in human visual cortex

Abstract:

Reactivation of distributed neural activity is thought to underlie memory recall. Despite many positive findings of reactivation in the literature, it is not known whether mnemonic activity exhibits distinct properties from feedforward perceptual activity. In this talk, I will describe research using population receptive field models to quantify spatial activity in human visual cortex during stimulus perception and cued memory retrieval. Using this approach, I will show data confirming earlier findings that retinotopic organization in visual cortex is conserved during recall. I will also argue that there are large, systematic differences in visual cortical tuning properties measured during perception versus memory. Most notably, I will show evidence that the three-fold change in spatial precision observed across the visual hierarchy during perception is entirely abolished during memory. I will describe simulations showing that this effect is unlikely to be caused by reduced signal-to-noise or by imperfect task performance. Finally, I will briefly discuss a plausible framework for understanding these findings as well as ongoing extensions to this work.