The Penn Frontotemporal Degeneration Center conducts several studies to improve our understanding of the neural basis for number knowledge. Individual use numbers and quantities throughout daily life: counting money, writing checks, preparing meals, and “telling time”. Patients with Corticobasal Syndrome (CBS) may have limitations associated with number knowledge and studies in our center have related this deficit to parietal cortex disease. CBS patients can have difficulty counting small numbers and performing basic addition. Other patients, including those with behavioral variant Frontotemporal degeneration , can have some difficulty with complex calculations like division and this has been related to executive limitations associated with frontal cortex disease. Number knowledge is relatively preserved in individuals with the semantic variant of primary progressive aphasia (semantic dementia), even though these individuals have considerable difficulty with object knowledge.
Several ongoing studies in our Center have investigated how number knowledge limitations impact the comprehension of words that refer to quantities of objects, like “some”, “many”, “all”, and “most”. These words, called “quantifiers”, are extraordinarily frequent in daily language. We have related quantifier comprehension to a large-scale fronto-parietal network that can be affected by CBS and bvFTD. More recently, we have been developing formal models of quantifier comprehension that are based on game theory and economics. These studies provide a novel method for understanding quantity and even how individuals may choose to use one quantifier instead of another quantifier in different social contexts.