Re-acquisition of person knowledge in semantic memory disorders

Abstract

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.

Dissociation of explicit and implicit long-term memory consolidation in semantic dementia: A case study

“…performed at ceiling level 6 months post-training when aided by the trained contextual cue. Two more recent studies (Dewar et al, 2009;Jokel, Rochon, & Leonard, 2006) have replicated these findings in SD cases, indicating that newly learnt information rapidly declines within weeks when no maintenance of the knowledge is provided.…”

“…In contrast to their profound semantic deficits, patients with SD show relatively intact episodic memory, particularly for visual material (e.g., Lee, Rahman, Hodges, Sahakian, & Graham, 2003;Simons, Graham, Galton, Patterson, & Hodges, 2001). Moreover, their day-to-day memory is well preserved with good episodic memory performance even after a 24-hour delay (Adlam, Patterson, & Hodges, 2009 & Graham, 2009;Graham, Patterson, Pratt, & Hodges, 1999;Murray, Koenig, Antani, McCawley, & Grossman, 2007;Snowden & Neary, 2002). One potential reason for these mixed results is that memory consolidation processes may be affected thus hindering the long-term retention of new information.…”

“…There is debate in the literature concerning the best time frame for patients to relearn words and at what time interval these need to be re-activated. In most previous SD case re-learning studies (Dewar et al, 2009;Graham et al, 1999;Jokel et al, 2006;Snowden & Neary, 2002) daily rehearsal of stimuli lists significantly improved patient performance. This approach does not, however, always result in a beneficial effect as the daily repetition of items can cause an increased stress in the patient (Graham et al, 1999).…”

Effect of Lexical Retrieval Cascade Treatment on Naming and Discourse of Individuals with Logopenic Variant of Primary Progressive Aphasia (lvPPA)

“…Recent studies have tried to fulfill this need by using personalized materials such as digital photos of individual household items 29 or by training relevant activities for the patient such as cooking, as in the study of Bier et al 31 The impact of interventions on connected speech measures or quality of life has not been consistently investigated in studies and when reported have shown modest results. 19,20,28 Future studies should address functional communication measures such as analysis of discursive skills to reliably establish transference of therapy gains.…”

“…Snowden and Neary 13 ) with a few exceptions. 19,24,25,27,28 This aspect should be a point of concern when selecting the set of stimuli to be trained and may also suggest the need for more context-based interventions. Recent studies have tried to fulfill this need by using personalized materials such as digital photos of individual household items 29 or by training relevant activities for the patient such as cooking, as in the study of Bier et al 31 The impact of interventions on connected speech measures or quality of life has not been consistently investigated in studies and when reported have shown modest results.…”