Speed of lexical access relates to quality of neural response to sound, not cognitive abilities, in younger and older adults

Abstract

Previous work has demonstrated a relationship between age-related declines in inhibitory control and difficulties identifying words of low lexical frequency and high neighborhood density (Sommers & Danielson, 1999). We hypothesized that declines in consistency of the auditory brainstem response (ABR; neural response to a repeated sound; Anderson et al., 2012) might also impede lexical access in older adults. We measured audiometric thresholds, ABR consistency, vocabulary, inhibitory control, and working memory in two groups (younger: 18-23yo, n = 41; older: 54-76yo, n = 41). We used mean target fixation proportion from 200 to 750 ms after word onset in a visual world task as a proxy for lexical access speed as listeners identified spoken words (varying on low/high: lexical frequency, neighborhood density, and cohort density; Magnuson et al., 2007). ABR consistency significantly predicted speed of word identification across variations in neighborhood and cohort densities, but contra previous findings, cognitive measures did not improve model fits. Interactions involving age, vocabulary, and lexical frequency suggest age-related linguistic expertise influences lexical access of uncommon words. We conclude that older adults exhibit increases in phonological competition due to declines in auditory encoding, suggesting that a consistent neural response to sounds leads to more efficient speech processing and lexical access.

Subconcussive changes in youth football players: objective evidence using brain vital signs and instrumented accelerometers

“… 19 , 23 Early PMN changes have been described with respect to basic mechanisms of comprehension involved in literacy development. 24 Indeed, lexical word access can occur as early as 200 ms. 25 Accordingly, the specific N400 (and PMN) changes in subconcussion are of potential clinical importance.…”

Sensory and cognitive contributions to age‐related changes in spoken word recognition

“…Listeners with low auditory encoding fidelity (as measured by temporal encoding fidelity and/or neural response consistency) might, as a consequence, not accurately encode subtle but meaningful phonetic distinctions, which, we propose, could lead to increased difficulty during lexical access. Indeed, results from a recent study suggest that high ABR consistency leads to faster word recognition (Johns, Myers, Skoe, & Magnuson, 2017). Consider that reduced auditory encoding fidelity could contribute to increased competition as follows: unreliable or inconsistent neural responses to sound might lead to a less precise, "fuzzy" neural encoding of the speech input.…”