Age-related differences in the neural bases of phonological and semantic processes in the context of task-irrelevant information.
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2019-08
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As we age we have increasing difficulty with phonological aspects of language production. Yet semantic processes are largely stable across the life span. This suggests a fundamental difference in the cognitive and potentially neural architecture supporting these systems. Moreover, language processes such as these interact with other cognitive processes that also show age-related decline, such as executive function and inhibition. The present study examined phonological and semantic processes in the presence of task-irrelevant information to examine the influence of such material on language production. Older and younger adults made phonological and semantic decisions about pictures in the presence of either phonologically or semantically related words, which were unrelated to the task. FMRI activation during the semantic condition showed that all adults engaged typical left-hemisphere language regions, and that this activation was positively correlated with efficiency across all adults. In contrast, the phonological condition elicited activation in bilateral precuneus and cingulate, with no clear brain-behavior relationship. Similarly, older adults exhibited greater activation than younger adults in several regions that were unrelated to behavioral performance. Our results suggest that as we age, brain-behavior relations decline, and there is an increased reliance on both language-specific and domain-general brain regions that are seen most prominently during phonological processing. In contrast, the core semantic system continues to be engaged throughout the life span, even in the presence of task-irrelevant information.
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Diaz, Michele T, Micah A Johnson, Deborah M Burke, Trong-Kha Truong and David J Madden (2019). Age-related differences in the neural bases of phonological and semantic processes in the context of task-irrelevant information. Cognitive, affective & behavioral neuroscience, 19(4). pp. 829–844. 10.3758/s13415-018-00671-2 Retrieved from https://hdl.handle.net/10161/22528.
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Trong-Kha Truong
I co-lead the MR Engineering Lab, which is part of the Brain Imaging and Analysis Center at Duke University. Our research involves the development of novel magnetic resonance imaging (MRI) coil technologies – in particular integrated parallel reception, excitation, and shimming (iPRES) and integrated radio-frequency/wireless (iRFW) coils – to enable imaging, localized B0 shimming, and/or wireless communication with a single coil, thereby improving the image quality and clinical utility of MRI applications such as functional MRI and diffusion-weighted imaging in the human brain and body. We also develop high-resolution diffusion tensor imaging techniques to investigate the microstructure of the human brain and to detect abnormalities in neurological disorders such as Alzheimer’s disease.
David Joseph Madden
My research focuses primarily on the cognitive neuroscience of aging: the investigation of age-related changes in perception, attention, and memory, using both behavioral measures and neuroimaging techniques, including positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI).
The behavioral measures have focused on reaction time, with the goal of distinguishing age-related changes in specific cognitive abilities from more general effects arising from a slowing in elementary perceptual processes. The cognitive abilities of interest include selective attention as measured in visual search tasks, semantic and episodic memory retrieval, and executive control processes.
The behavioral measures are necessary to define the cognitive abilities of interest, and the neuroimaging techniques help define the functional neuroanatomy of those abilities. The PET and fMRI measures provide information regarding neural activity during cognitive performance. DTI is a recently developed technique that images the structural integrity of white matter. The white matter tracts of the brain provide critical pathways linking the gray matter regions, and thus this work will complement the studies using PET and fMRI that focus on gray matter activation.
A current focus of the research program is the functional connectivity among regions, not only during cognitive task performance but also during rest. These latter measures, referred to as intrinsic functional connectivity, are beginning to show promise as an index of overall brain functional efficiency, which can be assessed without the implementation of a specific cognitive task. From DTI, information can be obtained regarding how anatomical connectivity constrains intrinsic functional connectivity. It will be important to determine the relative influence of white matter pathway integrity, intrinsic functional connectivity, and task-related functional connectivity, as mediators of age-related differences in behavioral measures of cognitive performance.
Ultimately, the research program can help link age-related changes in cognitive performance to changes in the structure and function of specific neural systems. The results also have implications for clinical translation, in terms of the identification of neural biomarkers for the diagnosis of neural pathology and targeting rehabilitation procedures.
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