Verbal working memory (VWM) is the ability to dynamically preserve and manipulate verbal information for brief periods of time. VWM is maintained through a silent inner speech process (Baddeley, 1986; Baddeley & Hitch, 1974). It is well established in the behavioral and neuroimaging literature that VWM can be disrupted by the simultaneous (concurrent) performance of simple speech tasks (e.g. overt concurrent articulation of a word or digit) (Caplan et al., 2000; Larsen & Baddeley, 2003). Our primary goal in these experiments is to test whether VWM and overt concurrent articulation will have one or more overlapping regions of activation in areas commonly associated with speech processing, and to determine whether such regions are active during simple tapping tasks. Due to concerns about overt movement artifacts, we also explore covert version of speech and tapping tasks. Experiment 1 was a behavioral study that examined the effects of overt and covert concurrent articulation and finger tapping on VWM. We found that overtly and covertly concurrently articulating the were the most detrimental to subjects recall ability. These effects could be attributed to dual-task interference effects at the level of inner speech in VWM, thus, indicating a shared set of neural regions for all speech and VWM. At the same time, the effect sizes were different for the overt and covert versions of our tasks, raising questions about the common assumption of shared substrates. Experiment 2 was an imaging study designed to examine whether there were shared neural regions between simple speech tasks and VWM and to further explore differences between overt and covert tasks. The results from this experiment provided only weak evidence implicating two candidate regions as the shared locus of activation: the left cerebellum and left superior temporal gyrus. We also found interesting evidence in support of distinct sets of regions for overt versus covert versions of the tasks.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-12072006-112122 |
| Date | 23 January 2007 |
| Creators | Durisko, Corrine |
| Contributors | Julie Fiez, Marc Sommer, Carol Colby |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-12072006-112122/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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