A MEG investigation of lexical access in aphasia

Aphasia is an acquired impairment of language ability that occurs secondary to brain damage, and auditory comprehension deficits are a defining component of aphasia. At the single-word level, these deficits are thought to arise from impaired phonological processing, semantic representations, or both. The present study examined spreading lexical activation in people with aphasia by implementing thorough clinical evaluation, a series of listening tasks, and a time sensitive means of tracking cortical activation. Magnetoencephalography (MEG) was used to measure the cortical activity of 7 people with aphasia, 9 age-matched control participants, and 10 younger control participants as they completed an auditory lexical decision task and a passive listening task with phonemes. In the lexical decision task, target words were presented in three conditions of interest: semantically primed, where the target was preceded by a related word; identity primed, where the target was preceded by itself; and a control condition, where the target was preceded by an unrelated word. Behavioral reaction times and MEG data were collected in response to each target, and the M350, a MEG signal associated with lexical processing, was evaluated. MEG data collected during the passive listening task were used to evaluate the mismatch field (MMF), a response associated with the formation of an auditory memory trace. Analysis was conducted at both the group and single-subject levels.

Department dc:contributor.department

Harvard University--MIT Division of Health Sciences and Technology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Zipse, Lauryn Rose

Advisor dc:contributor.advisor

• Kevin P. Kearns.

• Harvard University--MIT Division of Health Sciences and Technology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/46658

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/46658