Research in the brain and cognitive sciences provides overwhelming evidence that even seemingly simple tasks like understanding spoken words rely on the interaction of a variety different types of information (e.g. auditory, phonetic, phonological, lexical, semantic etc.). These interactions are remarkable in that they appear to allow listeners, including many stroke patients with focal damage to brain regions that are responsible representing these types of information, to recognize spoken language, even when speech is unclear due to poor articulation, imperfect speech synthesis, noisy environments, or poor signal quality due to digital reduction or filtering (e.g. when experienced via cochlear implant, hearing aids, or a poor phone connection). There is still vigorous debate about the nature or necessity of many of these interactions due to intrinsic limitations in the interpretability of current behavioral and unimodal imaging paradigms. This proposal addresses these limitations by integrating MRI, MEG and EEG data to provide high spatiotemporal resolution images of evolving brain activation during speech perception tasks. These data will be submitted to Granger causality analysis, which allows researchers to directly examine patterns of cause and effect in the relationship between activation of different brain regions associated with the processing of specific types of information. Using these techniques, the proposed research examines the mechanisms that give rise to: (1) the discrete categorization of speech sounds (categorical perception), (2) frequency or phonotactic effects on the perception of speech sounds, (3) the influence of semantic context on speech perception. Having identified how localized functions interact to produce robust speech perception in unimpaired listeners, these tools will then be turned to examine how preserved processes are reorganized and integrated after unilateral focal brain damage in the 18 months following stroke, to allow the recovery of function in aphasic patients. These data address central, previously irresolvable questions about brain function, the robustness of human speech perception, and the mechanisms that support recovery in aphasic patients. As basic research, the work should have wide-reaching implications for the study, assessment, and rehabilitation of patients with focal damage.

Public Health Relevance

Aphasia is a common neurological condition affecting the ability of roughly one million Americans to communicate using language (National Institute on Deafness and Other Communication Disorders, 1997). Despite the fact that aphasia is generally the result of irreversible brain damage, aphasics show differing levels of functional recovery associated and new patterns of brain activation during language tasks (Heiss &Thiel, 2006). The proposed work will characterize patterns of interaction in brain activity in unimpaired listeners and examine how these patterns of activation are integrated with preserved brain function to produce improved language understanding over time in people with aphasia.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC003108-13
Application #
8131659
Study Section
Language and Communication Study Section (LCOM)
Program Officer
Shekim, Lana O
Project Start
1998-02-01
Project End
2014-08-31
Budget Start
2011-09-01
Budget End
2012-08-31
Support Year
13
Fiscal Year
2011
Total Cost
$359,572
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
073130411
City
Boston
State
MA
Country
United States
Zip Code
02199
Gow Jr, David W; Ahlfors, Seppo P (2017) Tracking reorganization of large-scale effective connectivity in aphasia following right hemisphere stroke. Brain Lang 170:12-17
Gow Jr, David W; Olson, Bruna B (2016) Sentential influences on acoustic-phonetic processing: A Granger causality analysis of multimodal imaging data. Lang Cogn Neurosci 31:841-855
Gow Jr, David W; Olson, Bruna B (2016) Using effective connectivity analyses to understand processing architecture: Response to commentaries by Samuel, Spivey and McQueen, Eisner and Norris. Lang Cogn Neurosci 31:869-875
Gow Jr, David W; Olson, Bruna B (2015) Lexical mediation of phonotactic frequency effects on spoken word recognition: A Granger causality analysis of MRI-constrained MEG/EEG data. J Mem Lang 82:41-55
Gow Jr, David W; Nied, A Conrad (2014) Rules from words: a dynamic neural basis for a lawful linguistic process. PLoS One 9:e86212
Rapp, Brenda; Caplan, David; Edwards, Susan et al. (2013) Neuroimaging in aphasia treatment research: issues of experimental design for relating cognitive to neural changes. Neuroimage 73:200-7
Gow Jr, David W; Caplan, David N (2012) New levels of language processing complexity and organization revealed by granger causation. Front Psychol 3:506
Gow Jr, David W (2012) The cortical organization of lexical knowledge: a dual lexicon model of spoken language processing. Brain Lang 121:273-88
Caplan, David; Gow, David (2012) Effects of tasks on BOLD signal responses to sentence contrasts: Review and commentary. Brain Lang 120:174-86
Gow Jr, David W; Keller, Corey J; Eskandar, Emad et al. (2009) Parallel versus serial processing dependencies in the perisylvian speech network: a Granger analysis of intracranial EEG data. Brain Lang 110:43-8

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