Poster E55, Monday, March 26, 2:30-4:30 pm, Exhibit Hall C
Impaired metaphor comprehension in primary progressive aphasia
Eileen Cardillo1, Nathaniel B. Klooster1, Marguerite McQuire1, Michael Bonner1, Charles Jester1, Murray Grossman1, Corey McMillan1, Anjan Chatterjee1; 1University of Pennsylvania
Patients with focal brain lesions can display impairments in comprehending metaphor despite not showing difficulty with literal language. This observation suggests that figurative language abilities are especially vulnerable to brain injury. Here we test metaphor comprehension in 12 patients with a neurodegenerative condition, the logopenic variant of Primary Progressive Aphasia (lvPPA), compared to 19 matched healthy comparison participants (HCs). Stimuli consisted of unfamiliar nominal metaphors and matched literal sentences sharing the same source term (The interview was a painful crawl/ The infant’s motion was a crawl). Sentences were presented visually, followed by four adjective-noun answer choices (one target and three foils). Participants were instructed to select the phrase that best matched the meaning of the sentence. Linear mixed-effects analyses revealed an interaction between group and figurativeness. Although they performed reliably better on literal sentences, HCs displayed good comprehension for both conditions. PPA patients, by contrast, performed especially poorly on metaphoric sentences. Compared to a sample of 35 age-matched healthy controls, patients exhibited significant cortical atrophy in left frontal and temporal-parietal areas, a distribution that includes areas previously identified as important for metaphor (e.g. posterior middle temporal gyrus) but spares others (e.g. inferior prefrontal cortex). The disproportionate difficulty patients showed comprehending metaphors compared to closely matched literal sentences supports the idea that metaphoric abstraction is a sensitive and relatively early index of cognitive dysfunction. That this pattern was observed in a group of patients with exclusively left hemisphere injury also challenges a privileged role for the right hemisphere in processing metaphors.
Topic Area: LANGUAGE: Semantic