Age-Related Changes in Language Processing

Washington University, Saint Louis MO

Investigators

Linked publications, trials & patents

Abstract

Abstract Normal aging involves changes to sensory and cognitive systems that affect many aspects of life, including spoken communication. Speech comprehension involves rapidly mapping a complex acoustic signal to our knowledge of words and extracting higher-order meaning from sentence or story structure. When the sound signal is degraded?for example, due to background noise, or a listener?s poor hearing?this task is made more difficult. There is good evidence that in such cases of acoustic challenge listeners must engage additional cognitive resources supported by domain-general executive networks. Older adult listeners frequently have greater difficulty understanding and remembering speech in noise compared to young adults. Although some of this difficulty is due to age-related hearing loss, hearing ability alone cannot account for all of the comprehension changes that occur with age. One appealing explanation for older adults? increased speech comprehension difficulty is a more limited set of cognitive resources, making them unable to meet the cognitive demands of challenging listening situations. However, it is important to consider that a listener?s motivation to understand plays a critical role in communication. In the current grant we experimentally test the role of reward on language processing by varying the amount listeners are rewarded for correct responses during speech comprehension tasks. Reward is linked to dopamine-mediated pathways important for guiding learning and behavior. We hypothesize that increased reward (associated with greater motivation) will increase a listener?s use of executive processing resources, and result in greater speech intelligibility. Because normal aging is associated with changes in dopamine responsiveness, we expect that age differences in reward sensitivity may explain a portion of the age difference in speech comprehension. We will also conduct hierarchical statistical modeling to estimate the relative contributions of hearing ability, cognitive ability, and genetic correlates of dopamine function to listeners? success understanding speech in noise. The results will improve our understanding of factors that contribute to successful aging, and help identify mechanisms for intervention to improve performance when necessary.