Neural oscillations in the aging brain associated with interference control in word production

Abstract

Speaking is not only about retrieving words and structuring them into sentences, but it also requires top-down control to plan and execute speech. In previous electrophysiological research with young-adult speakers, mid-frontal theta oscillations have been observed using a picture-word interference paradigm. With this paradigm, participants name pictures while ignoring superimposed distractor words. In particular, mid-frontal theta power increases for categorically related distractors relative to other types of distractors, reflecting the top-down interference control in resolving the competition between processing streams during word production (Piai, Roelofs, Jensen, Schoffelen, & Bonnefond, 2014). In the present study, we conceptually replicated the magnetoencephalography study by Piai et al. (2014) with an older group of healthy adults (mean age of 60 years). Behaviorally, we replicated distractor semantic interference and Stroop-like interference effects usually observed in young adults. However, we did not find the corresponding theta modulation associated with these interference effects on the neural level. Instead, we found beta power decreases for both effects, mostly pronounced in the left posterior temporal and inferior parietal cortex. The distinct spectro-spatial-temporal profile of the oscillatory effects in the older population suggests different underlying dynamics relative to the midline frontal effect previously found in young-adult speakers. Our results indicate that the neural underpinnings of top-down interference control may be modified by aging, and that the mid-frontal theta cannot be the exclusive mechanism enabling interference control during spoken word production.