Jennifer E Mack1, M-Marsel Mesulam2, Emily J Rogalski3, Cynthia K Thompson4. 1. Roxelyn & Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, USA. Electronic address: jemack@umass.edu. 2. Mesulam Cognitive Neurology and Alzheimer's Disease Center, Northwestern University, USA; Ken & Ruth Davee Department of Neurology, Northwestern University, USA. 3. Mesulam Cognitive Neurology and Alzheimer's Disease Center, Northwestern University, USA; Department of Psychiatry and Behavioral Sciences, Northwestern University, USA. 4. Roxelyn & Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, USA; Mesulam Cognitive Neurology and Alzheimer's Disease Center, Northwestern University, USA; Ken & Ruth Davee Department of Neurology, Northwestern University, USA.
Abstract
BACKGROUND: Impaired sentence comprehension is observed in the three major subtypes of PPA, with distinct performance patterns relating to impairments in comprehending complex sentences in the agrammatic (PPA-G) and logopenic (PPA-L) variants and word comprehension in the semantic subtype (PPA-S). However, little is known about basic combinatory processes during sentence comprehension in PPA, such the integration of verbs with their subject and object(s) (verb-argument integration). METHODS: The present study used visual-world eye-tracking to examine real-time verb-argument integration in individuals with PPA (12 with PPA-G, 10 with PPA-L, and 6 with PPA-S) and neurotypical older adults (15). Two baseline experiments probed eye movement control, using a non-linguistic task, and noun comprehension, respectively. Two verb-argument integration experiments examined the effects of verb meaning on (a) lexical access of the verb's direct object (argument access) and (b) selection of a semantically-appropriate direct object (argument selection), respectively. Eye movement analyses were conducted only for trials with correct behavioral responses, allowing us to distinguish accuracy and online processing. RESULTS: The eye movement control experiment revealed no significant impairments in PPA, whereas the noun comprehension experiment revealed reduced accuracy and eye-movement latencies in PPA-S, and to a lesser extent PPA-G. In the argument access experiment, verb meaning facilitated argument access normally in PPA-G and PPA-L; in PPA-S, verb-meaning effects emerged on an atypical time course. In the argument selection experiment, significant impairments in accuracy were observed only in PPA-G, accompanied by markedly atypical eye movement patterns. CONCLUSION: This study revealed two distinct patterns of impaired verb-argument integration in PPA. In PPA-S, impaired verb-argument integration was observed in the argument access experiment, indicating impairments in basic semantic combinatory processes which likely relate to damage in ventral language pathways. In contrast, listeners with PPA-G showed marked impairments of argument selection, likely relating to damage to left inferior frontal regions.
BACKGROUND: Impaired sentence comprehension is observed in the three major subtypes of PPA, with distinct performance patterns relating to impairments in comprehending complex sentences in the agrammatic (PPA-G) and logopenic (PPA-L) variants and word comprehension in the semantic subtype (PPA-S). However, little is known about basic combinatory processes during sentence comprehension in PPA, such the integration of verbs with their subject and object(s) (verb-argument integration). METHODS: The present study used visual-world eye-tracking to examine real-time verb-argument integration in individuals with PPA (12 with PPA-G, 10 with PPA-L, and 6 with PPA-S) and neurotypical older adults (15). Two baseline experiments probed eye movement control, using a non-linguistic task, and noun comprehension, respectively. Two verb-argument integration experiments examined the effects of verb meaning on (a) lexical access of the verb's direct object (argument access) and (b) selection of a semantically-appropriate direct object (argument selection), respectively. Eye movement analyses were conducted only for trials with correct behavioral responses, allowing us to distinguish accuracy and online processing. RESULTS: The eye movement control experiment revealed no significant impairments in PPA, whereas the noun comprehension experiment revealed reduced accuracy and eye-movement latencies in PPA-S, and to a lesser extent PPA-G. In the argument access experiment, verb meaning facilitated argument access normally in PPA-G and PPA-L; in PPA-S, verb-meaning effects emerged on an atypical time course. In the argument selection experiment, significant impairments in accuracy were observed only in PPA-G, accompanied by markedly atypical eye movement patterns. CONCLUSION: This study revealed two distinct patterns of impaired verb-argument integration in PPA. In PPA-S, impaired verb-argument integration was observed in the argument access experiment, indicating impairments in basic semantic combinatory processes which likely relate to damage in ventral language pathways. In contrast, listeners with PPA-G showed marked impairments of argument selection, likely relating to damage to left inferior frontal regions.
Authors: Myrna F Schwartz; Daniel Y Kimberg; Grant M Walker; Adelyn Brecher; Olufunsho K Faseyitan; Gary S Dell; Daniel Mirman; H Branch Coslett Journal: Proc Natl Acad Sci U S A Date: 2011-05-03 Impact factor: 11.205
Authors: Jennifer E Mack; Sarah D Chandler; Aya Meltzer-Asscher; Emily Rogalski; Sandra Weintraub; M-Marsel Mesulam; Cynthia K Thompson Journal: Neuropsychologia Date: 2015-08-20 Impact factor: 3.139