Language and the Aging Brain

Speakers:
Naftali Raz, Wayne State University
Lorraine Tyler, University of Cambridge
Jonathan Peelle, Washington University
Pascale Tremblay, Université Laval

Chair: Greig de Zubicaray, Queensland University of Technology

Saturday, October 17, 12:00 – 1:45 pm, Grand Ballroom

This special symposium will discuss how aging affects the neurobiology of language. We have invited Prof. Naftali Raz to begin the session by reviewing the progress being made in understanding the mechanisms and factors of neural change in aging. His talk will be followed with presentations by three SNL members, Lorraine Tyler, Jonathan Peelle, and Pascale Tremblay. They will discuss whether or not aging affects some of the different levels of language processing — speech perception, speech production, or syntactic comprehension — and the neurobiological underpinnings of their findings. A final discussion period will allow meeting attendees to ask questions or discuss different issues raised by these presentations.

Aging of the Brain: Its Modifiers and Cognitive Correlates

Brain and cognition change with age but the rates of change differ among individuals and across brain regions and cognitive domains. The mechanisms of these differential changes remain unclear. Multiple factors associated with vascular and metabolic risk, inflammation, stress, accumulation of reactive oxygen species and beta-amyloid modify the course of aging. Genetic variants that alter availability and metabolism of hormones, enzymes and neurotransmitters also contribute to individual variation in age-related rates of change. Interventions that ameliorate the negative modifiers, e.g., exercise and active life-style inspire cautious optimism as they promise mitigating age-related declines. I will review the progress in understanding brain aging and its impact on cognition with a specific emphasis on long-term longitudinal studies.

Naftali Raz received his B.A. in Psychology from Hebrew University in Jerusalem, Israel and a Ph.D. in Psychology from The University of Texas at Austin. His work focuses on longitudinal studies of normal aging of the brain and cognition, and the influence of physiological and genetic risk factors on individual trajectories of change. His work is funded by the National Institute on Aging. Naftali Raz is currently a Professor of Psychology and an Associate Director for Life-Span Cognitive Neuroscience at the Institute of Gerontology, Wayne State University, Detroit, MI.

The adaptive brain: brain and cognition in ageing

Language comprehension is a complex system that involves the rapid transformation of the speech input into various different types of representation. In spite of the multiple rapid computations involved, there is little evidence that aging significantly impairs normal language comprehension.  Focusing on syntactic processing during natural listening, we find no evidence for functional compensation of the left hemisphere specialized syntax network. While age-related decreases in grey matter are associated with weakened connectivity within the syntax network and increased inter-hemispheric connectivity elsewhere, these changes are related to poorer performance and therefore are not evidence for successful compensation. Where we do see functional compensation is during experimental paradigms that place additional cognitive demands on the listener. Under these conditions, older listeners show increased activation of domain-general (but not domain specific) networks that are associated with improved performance. Overall, this research suggests that in the context of widespread age-related grey matter changes, preserved syntactic comprehension depends on the residue of the domain-specific language system and that this system does not functionally reorganize. I will discuss these findings in relation to current neurocognitive models of aging.

Lorraine Tyler works on the cognitive psychology, cognitive neuropsychology, and cognitive neuroscience of perception, language and meaning. She heads two major research groups at the University of Cambridge: the Centre for Speech, Language and the Brain (CSLB) and the Cambridge Centre for Ageing and Neuroscience (Cam-CAN), which studies how age-related changes in brain structure and function relate to patterns of preserved and declining cognitive functions with age. She has been awarded Fellowships of the British Academy, the Academia Europaea, the Association for Psychological Science and the British Psychological Society, as well as publishing over 170 articles in academic journals and books.

Individual differences in auditory and cognitive factors during spoken language comprehension

Understanding spoken language relies on joint contributions from incoming acoustic information and cognitive systems that allow us to extract meaning from these signals. I will review evidence that individual differences in hearing sensitivity and cognitive ability jointly contribute to the processing of spoken language, affecting the cognitive and neural systems listeners engage during speech comprehension. Although frequently studied in the context of adult aging, these principles have broader implications for our understanding of how auditory and cognitive factors interact during spoken language comprehension.

Jonathan Peelle is an assistant professor in the Department of Otolaryngology at Washington University in Saint Louis. He obtained his PhD in neuroscience from Brandeis University, and went on for postdoctoral training in cognitive neuroscience and neuroimaging in the Department of Neurology at the University of Pennsylvania and at the MRC Cognition and Brain Sciences Unit in Cambridge, England. Dr. Peelle’s research investigates the neuroscience of speech comprehension, aging, and hearing impairment using a combination of behavioral and brain imaging methods.

Speech production in aging: from behaviour to brain imaging

Despite the importance of verbal communication on quality of life, the manner and extent to which speech production mechanisms, from respiration to articulation, change throughout adulthood, as well as the nature and extent of the physiological and neurobiological mechanisms that underlie these changes, remain poorly understood. In this talk I will discuss recent experiments from my lab that explored the behavioural changes in speech production that occur with age as well as the physiological, neurostructural and neurofunctional mechanisms that underlie these changes. The results of all these experiments reveal that the decline in speech production that occurs with age has a complex, multifactorial aetiology. Future research directions will be discussed.

Pascale Tremblay is assistant professor at Université Laval in Québec City since 2011 and director of the Speech and Hearing Neurosciences Lab (www.speechneurolab.ca). Her research focuses on understanding the neural mechanisms that support the ability to perceive and produce speech in adults and throughout aging, using state-of-the-art cognitive neuroscience research methods such as functional and anatomical brain imaging methods and transcranial magnetic brain stimulation. She also works towards characterizing the behavioural and physiological effects of brain aging on speech and voice perception and production using modern behavioural and physiological approaches, such as facial electromyography, measures of facial muscle force and endurance, speech errors and acoustics.