The Effect of Attention on Repetition Suppression and Multivoxel Pattern Similarity

Abstract

Fundamental to our understanding of learning is the role of attention. We investigated how attention affects two fMRI measures of stimulus-specific memory: repetition suppression (RS) and pattern similarity (PS). RS refers to the decreased fMRI signal when a stimulus is repeated, and it is sensitive to manipulations of attention and task demands. In PS, region-wide voxel-level patterns of responses are evaluated for their similarity across repeated presentations of a stimulus. More similarity across presentations is related to better learning, but the role of attention on PS is not known. Here, we directly compared these measures during the visual repetition of scenes while manipulating attention. Consistent with previous findings, we observed RS in the scene-sensitive parahippocampal place area only when a scene was attended both at initial presentation and upon repetition in subsequent trials, indicating that attention is important for RS. Likewise, we observed greater PS in response to repeated pairs of scenes when both instances of the scene were attended than when either or both were ignored. However, RS and PS did not correlate on either a scene-by-scene or subject-by-subject basis, and PS measures revealed above-chance similarity even when stimuli were ignored. Thus, attention has different effects on RS and PS measures of perceptual repetition.

Similarity Breeds Proximity: Pattern Similarity within and across Contexts Is Related to Later Mnemonic Judgments of Temporal Proximity

“…At the same time, PS in hippocampus and LO were related to temporal memory (differentially across the context conditions). There is growing evidence that RS and PS may index different types of information and that they may therefore show distinct relationships with memory depending on how memory is assessed (Moore et al, 2013; Ward et al, 2013). PS across item repetitions has been shown to support explicit item memory and is hypothesized to do so via reactivation of the initial encoding event (Xue et al, 2010).…”

Repetition suppression and its contextual determinants in predictive coding

“…Crucially, DCM revealed that the effect of attention was mediated by changes in descending connectivity from higher to lower auditory regions, targeting inhibitory interneurons in primary auditory cortex. This finding was consistent with previous fMRI studies in the visual domain, showing that repetition suppression of BOLD responses is modulated by spatial attention (Eger et al., 2004, Henson and Mouchlianitis, 2007) as well as feature-based attention (Moore et al., 2013, Yi and Chun, 2005, Yi et al., 2006). Although some forms of repetition suppression or mismatch responses can be preserved in the absence of attention (cf.…”

Distinct Neural Suppression and Encoding Effects for Conceptual Novelty and Familiarity

“…To allow for unbiased interpretation of the results, we modified the encoding task to produce similar memory rates for familiar and novel trials. This modification additionally equated the behavioral responses associated with novelty and familiarity during the encoding task; thus, we were able to rule out alternative explanations attributing different neural patterns to different behavioral responses (different behavioral responses have been demonstrated to result in different neural and behavioral effects in congruency and RS paradigms; e.g., Bein et al, 2015;Moore, Yi, & Chun, 2013;Henson, Shallice, Gorno-Tempini, & Dolan, 2002).…”