Re-acquisition of person knowledge in semantic memory disorders

Semantic memory impairment, from either non-progressive or neurodegenerative brain injury, has a significant impact on day-to-day functioning. Few studies have investigated the best methods for supporting relearning of new semantic knowledge in semantically-impaired individuals, even though these investigations also provide an opportunity to explore how the hippocampal and temporal neocortical systems interact in the acquisition of semantic facts. In the current study, four participants (three who had suffered from herpes simplex viral encephalitis and one with a diagnosis of semantic dementia) were asked to learn new facts about famous people using mnemonic and errorless learning paradigms. Home practice was also encouraged. Training resulted in significant improvements to all participants' naming of the individual and recall of a semantic fact about the famous person. Learning was maintained when home practice ceased. Learning also generalised to naming of a different photograph in three individuals, although generalisation of naming to a different semantic fact was less robust. This study confirms that errorless learning paradigms can be used to help boost naming and semantic knowledge in semantically-impaired individuals. This finding supports theoretical accounts in which different temporal structures are capable of supporting acquisition of new semantic facts independently, albeit less efficiently than when both systems are available.