The neural substrate of expressive language functions in healthy and pathological aging
Final Report Abstract
Word-retrieval difficulties are frequent in healthy aging and age-related pathological processes (e.g., demantia and its precursors, post-stroke language disorders). However, the neurofunctional basis of these impairments is largely elusive and a thorough understanding of activity changes associated with healthy aging is a prerequisite for interpreting functional imaging findings in age-related pathological conditions. Across cognitive domains, normal aging is frequently associated with reduced asymmetrical processing in prefrontal areas and the hemisphere that is not dominant for a given task is more active in older compared to younger adults. However, the neurofunctional basis of word-retrieval deficits in normal aging has rarely been assessed. Across several studies we could show that (a) healthy older adults compared to younger adults show increased task positive activity in the right hemisphere that is not dominant for the task (b) and that task negative activity is reduced in older adults. (c) this pattern progresses with age in cross-sectional samples and is (d) not beneficial to performance, i.e., negatively correlated with performance. (e) However, we also found that task difficulty is a crucial mediator of lateralization, irrespective of age which needs to be taken in account when interpreting age-related functional activity changes. Our studies contribute to an understanding of neurofunctional changes associated with language impairments in old age and lay the foundation to further specifiy the functional role of activity changes in healthy aging. In future studies this will be accomplished by combining functional and structural imaging techniqes and by using non-invasive brain stimulation techniques.
Publications
- (2008) Functional imaging studies of treatment-induced recovery in chronic aphasia. Aphasiology 22, 1251-1268
Meinzer M. & Breitenstein B.
- (2009) Clinical implications of fMRI studies on treatment induced improvement in chronic aphasia. Neurologie & Rehabilitation 15:255-263 [German]
Meinzer M., Breitenstein C., Knecht S.
- (2009) Electromagnetic brain activity in higher frequency bands during automatic word processing indicates recovery of function in aphasia. European Journal of Physical and Rehabilitation Medicine 45:369-378
Meinzer M., Paul I., Wienbruch C., Djundja D., Rockstroh B.
- (2009) Imaging short- and long-term training success in chronic aphasia. BMC Neuroscience 10:118
Meinzer M., Menke R., Kugel H., Deppe M., Baumgaertner A., Schiffbauer H., Thomas M., Kramer K., Lohmann H., Knecht S., Breitenstein C.
- (2009) Neural signatures of semantic and phonemic fluency in young and old adults. Journal of Cognitive Neuroscience 21:2007-2018
Meinzer M., Flaisch T., Wilser L., Eulitz C., Rockstroh B., Conway T., Gonzalez- Rothi L., Crosson B.
- (2009) Opaque for the reader but transparent for the brain: Neural signatures of morphological complexity. Neuropsychologia 47: 1964-1971
Meinzer M., Lahiri A., Flaisch T., Hannemann R., Eulitz C.
- (2009) The representation of the verb's argument structure as disclosed by fMRI. BMC Neuroscience 10:3
Assadollahi R., Meinzer M., Flaisch T, Obleser J., Rockstroh B.
- (2010) Functional imaging and related techniques: A brief introduction for rehabilitation researchers. Journal of Rehabilitation Research & Development 47:12-33
Crosson B., Ford A., McGregor K., Meinzer M., Cheshkov S, Liu X., Walker-Batson D, Briggs R.
- (2010) Integrity of the hippocampus and surrounding white matter is correlated with language training success in chronic aphasia. NeuroImage 53:283-290
Meinzer M., Mohammedi S., Kugel H., Schiffbauer H., Flöel A., Albers J., Kramer K., Baumgaertner A., Knecht S., Breitenstein C., Deppe M.
- (2010) Visual discrimination predicts naming and semantic association accuracy in Alzheimer’s Disease. Cognitive and Behavioral Neurology 23:231-9
Harnish S., Neils-Strunja, J., Eliassen J., Reilly J., Meinzer M., Clark J, Joseph J.
- (2011) Motor cortex pre-activation by standing facilitates word retrieval in aphasia. Neurorehabilitation and Neural Repair 25:178-87
Meinzer M., Breitenstein C., Westerhoff U., Rösser N., Sommer J., Rodriguez A., Harnish S., Knecht S., Flöel A.
