Verb production during action naming in semantic dementia

In contrast with widely documented deficits of semantic knowledge relating to object concepts and the corresponding nouns in semantic dementia (SD), little is known about action semantics and verb production in SD. The degradation of action semantic knowledge was studied in 5 patients with SD compared with 17 matched control participants in an action naming task based on video clips. The pattern of errors, involving a huge proportion of generic verbs (e.g. “to remove” versus “to peel”) relative to responses in control subjects, suggested a hierarchical, bottom-up deficit of action knowledge in SD patients. In addition, abnormal responses in patients consisted of verbs that were semantically related to the expected verbs produced by control subjects (e.g. “to undress” versus “to peel” for the action [To peel_orange]). This study suggests that, in SD, non-canonical responses to action naming reflect lack of both specificity and semantic relatedness relative to the expected responses.Learning outcomes: As a result of this activity, readers will recognize that semantic word knowledge disappears in semantic dementia using video clips of object-related actions. As a result of this activity, readers will discover that this semantic impairment followed a hierarchical pattern with the more specific verbs vanishing first.

Research highlights► We addressed how does semantic verb knowledge disappear in semantic dementia (SD) using video clips of object-related actions. ► This semantic impairment followed a hierarchical pattern according to which the more specific verbs vanished away first. ► Further, abnormal responses in patients consisted of verbs that were still semantically related to the expected verbs produced by control subjects. ► Although their semantic knowledge became progressively impoverished, SD patients did not violate semantic coherence between the stimulus and the response they made.