Individual Differences in Neural Representations of Semantic Content
Katherine L. Alfred1, Justin C. Hayes1, Rachel G. Pizzie1, David J. M. Kraemer1; 1Dartmouth College
Neuroimaging studies of semantic knowledge often report group effects collapsing across individual differences. Though such differences are often treated as noise, previous studies (Miller et al., 2002; 2011; Kraemer et al., 2009; 2014; Hsu et al., 2011) have shown that individual variability can reflect stable and measurable differences in neural activity. Furthermore, some of these differences (e.g., encoding strategies and cognitive style) account for significant variance after accounting for task manipulation and demographic differences. In this study, we focused on individual differences in cognitive processing on a continuum from verbal to visuospatial, during encoding of word lists and picture lists. Using an intentional encoding task during fMRI scanning, we manipulated stimulus type in a 2[format: words, images] x 2[semantic relevance: meaningful, nonsense] design. Analyzing functional activity during encoding, we used multivariate pattern analysis (MVPA) classification to probe for between-subject differences in separate brain networks that support language processing and mental imagery, respectively. Networks of interest were identified through meta-analyses of previous studies (drawn from NeuroSynth) as well as through functional localization within our participant group. Results indicate that inter-individual differences in verbal versus visuospatial processing account for variation in neural patterns corresponding to the differential use of these separate networks when presented with semantically-meaningful stimuli. These findings indicate that the neural representation of semantic content varies as a function of individual differences in verbal and visuospatial cognitive processing independently of the format of stimulus presentation.
Topic Area: THINKING: Reasoning