Abstract
Memory encoding is traditionally associated with the end stages of visual processing. However, not all images are perceived equally — some images carry a greater perceptual capacity and thus may have a higher likelihood of being remembered. How does the brain process these perceptually strong images compared to those that fade away? Here we tested the hypothesis that more memorable images show a greater neural perceptual trace (robust and sustained brain signals) than those that are less memorable. We collected MEG and fMRI data while participants viewed stimuli of low and high memorability scores from the LaMem Memorability image set (Khosla et al., 2015). The stimuli were balanced for low-level image statistics and high-level semantic content. To track the neural signals of memory through perception with high resolution in space and time, we coupled MEG and fMRI data (Cichy et al., 2014; 2016) using representational similarity analysis (Kriegeskorte et al., 2008). Results revealed that more memorable images recruited the medial and lateral regions of the ventral-visual processing stream to a greater degree than the less memorable images (Bainbridge et al., 2017). Importantly, by 100ms after image onset, we found a more robust representation for high memorable images in the fusiform gyrus, lateral occipital and parahippocampal cortices. The neural representations of memorable images were more sustained in time both during (online perception) and after (iconic memory) image presentation. This robust and sustained representation found in high level brain regions for more memorable images could point to the perceptual maintenance required to stimulate the visual system to encode the information into long-term memory. These findings challenge the assumption that memory and perception are functionally and anatomically segregated by demonstrating that we can trace the path of memorability early on through perceptual regions, prior to memory encoding.
Meeting abstract presented at VSS 2018