How the healthy ageing brain supports semantic binding during language comprehension

Abstract

Semantic binding refers to constructing complex meaning based on elementary building blocks. Using EEG, we investigated the age-related changes in modulations of oscillatory brain activity supporting semantic binding. Young and older adult participants were visually presented two-word phrases in a semantic binding (e.g. swift horse) vs. no semantic binding context (e.g. swrfeq horse). We found that the oscillatory brain activity associated with semantic binding significantly differed between healthy older and young adults. Specifically, in young adults we found a semantic binding signature in the low-beta range centred around the onset of the target word (i.e. a smaller low-beta increase for binding relative to no binding), while in healthy older adults we found an opposite pattern about ~500ms later in the low- and high-beta range (i.e. a smaller low- and high-beta decrease for binding relative to no binding). We interpret the different and delayed oscillatory signature for semantic binding in healthy older adults to reflect that they are relying on different mechanisms to integrate word meaning into their semantic context.