Some is not enough: Quantifier comprehension in corticobasal syndrome and behavioral variant frontotemporal dementia

Abstract

Quantifiers are very common in everyday speech, but we know little about their cognitive basis or neural representation. The present study examined comprehension of three classes of quantifiers that depend on different cognitive components in patients with focal neurodegenerative diseases. Patients evaluated the truth-value of a sentence containing a quantifier relative to a picture illustrating a small number of familiar objects, and performance was related to MRI grey matter atrophy using voxel-based morphometry. We found that patients with corticobasal syndrome (CBS) and posterior cortical atrophy (PCA) are significantly impaired in their comprehension of Cardinal Quantifiers (e.g. “At least three birds are on the branch”), due in part to their deficit in quantity knowledge. MRI analyses related this deficit to temporal-parietal atrophy found in CBS/PCA. We also found that patients with behavioral variant frontotemporal dementia (bvFTD) are significantly impaired in their comprehension of Logical Quantifiers (e.g. “Some the birds are on the branch”), associated with a simple form of perceptual logic, and this correlated with their deficit on executive measures. This deficit was related to disease in rostral prefrontal cortex in bvFTD. These patients were also impaired in their comprehension of Majority Quantifiers (e.g. “At least half of the birds are on the branch”), and this too was correlated with their deficit on executive measures. This was related to disease in the basal ganglia interrupting a frontal-striatal loop critical for executive functioning. These findings suggest that a large-scale frontal-parietal neural network plays a crucial role in quantifier comprehension, and that comprehension of specific classes of quantifiers may be selectively impaired in patients with focal neurodegenerative conditions in these areas.

The relative contributions of frontal and parietal cortex for generalized quantifier comprehension

“…Previous fMRI studies of quantifier comprehension have also consistently reported parietal cortex activation (McMillan et al, 2005; Troiani et al, 2009a; Heim et al, 2012) and patients with neurodegenerative disease in parietal cortex have difficulty with interpreting quantifier meaning (McMillan et al, 2005, 2006; Morgan et al, 2011; Troiani et al, 2009a). Together, these findings have been interpreted as evidence for the role of number knowledge contributing to quantifier comprehension.…”

Multimodal imaging evidence of pathology-mediated disease distribution in corticobasal syndrome

“…Primarily, the current study and others 2,19 suggest that both groups have parietal cortex disease in common. This locus of disease may contribute to cognitive dysfunction in CBS, including impairments in number knowledge [24][25][26][27] and linguistic discourse 28 that have been associated with parietal disease. Notably, while episodic memory was marginally more common in CBS-AD relative to CBS-non-AD, it was observed in only z30% of patients, suggesting that memory may not provide a salient biomarker for this form of atypical AD.…”

Dissociation of quantifiers and object nouns in speech in focal neurodegenerative disease

“…Finally, performance on the dot magnitude comparison task was correlated with quantifier comprehension in CBS. In another study, CBS and PCA patients were found to be impaired in their comprehension of cardinal quantifiers – those that depend directly on quantity knowledge, as in “There are more than two cows in the barn” – and their comprehension of this class of quantifiers was correlated with their accuracy in judging precise numbers (Morgan, et al, 2011). In a third study, the neural substrate of numerical quantifiers (e.g., “at least three”) was investigated in patients with CBS and healthy adults (Troiani, Peelle, Clark, & Grossman, 2009).…”

“…In a further fMRI study, we used BOLD fMRI in healthy young adults to investigate the relative contribution of frontal and parietal components to quantifier comprehension (Olm, McMillan, Spotorno, Clark, & Grossman, 2014). Participants performed a sentence-picture verification task similar to that used with patients in another study (Morgan, et al, 2011) to determine whether a sentence containing a quantifier accurately described a real-world naturalistic scene. A whole-brain analysis demonstrated activation of a fronto-parietal network during quantifier comprehension, including bilateral inferior parietal, superior parietal and dorsolateral prefrontal cortices, along with right inferior frontal cortex.…”

“…They have been found to be particularly impaired on higher-order or majority quantifiers that require a mental comparison, and this has been correlated with reverse digit span performance, a test of working memory (McMillan, et al, 2006). Another study found that bvFTD patients were impaired on these as well as on logical quantifiers, and their performance was correlated with executive measures (Morgan, et al, 2011). Deficits in quantifier comprehension in bvFTD were found to be related to disease in prefrontal regions.…”