Abstract

Objective: We compared activation related to contextual cues (semantic versus syntactic information) while older adults encoded verbal information. We hypothesized that semantic-focus would positively correlate with cognition and elicit greater activation within left middle temporal gyrus (MTG), pars triangularis (PT), and middle orbitofrontal gyrus (MOFG). Syntactic focus would negatively correlate with cognition and elicit greater activation within bilateral pars operculus (PO) and left middle frontal gyrus (MFG). Method: 32 older adults (ages 65–85) completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). BOLD activation within bilateral regions of interest (ROIs) was measured during a verbal encoding task: Participants read short phrases and categorized each by semantic (man-made versus nature related) or syntactic (present versus past tense) context. Intensity and number of voxels activated (per region and condition) were examined. Correlations between fMRI activation and cognition (RBANS scores) was examined. Results: Syntactic over semantic activation was observed within bilateral PO (p < .05 FWER) and MTG (uncorrected p < .001). Semantic over syntactic activation was observed within left ROIs and right MFG, MOFG, and MTG. Results demonstrated no correlation of RBANS scores and syntactic over semantic activation. Semantic over syntactic activation within left MOFG, left PO, and left PT (cluster = > 8 voxels, p < .05 FWER), and right MTG and PO (uncorrected p < .001) correlated positively with RBANS score. Conclusion(s): Findings support research describing older adult cortical dedifferentiation and increased activation during higher-level processes. Results suggest explicit semantic over implicit syntactic context as higher-level eliciting increased resources in older adults during encoding.