Semantic Inhibition and Analogical Reasoning in Prefrontal Cortex

Abstract:
Analogical reasoning relies on the ability to detect and manipulate relations among objects or events, while inhibiting irrelevant information. Prior studies suggest that prefrontal cortex plays a central role in these abilities. We compared verbal analogy performance of patients with frontal-variant frontotemporal dementia against that of brain damaged control patients and normal controls. Participants solved verbal analogies of the form: A:B::C:D or D' constructed from elementary vocabulary linked by one of five relational categories. Both patient groups performed well above chance; however, they made more errors than age- and education-matched normal controls. The two patient groups did not differ in accuracy. An analysis of the types of errors made by the patient groups indicated that frontal patients were significantly more likely than brain-damaged controls to make errors when the semantic association between the distractor choice (D') and the third term (C) in the analogy was greater than the semantic association between the correct relational choice (D) and the third term (C). These findings support the hypothesis that inhibition of semantic distractors may be an important component of verbal analogical reasoning that can be disrupted when the prefrontal cortex is damaged.