Quest for the best: effects of errorless and active encoding on word re-learning in semantic dementia.

Semantic dementia is a neurocognitive disorder characterised by a steady and progressive loss of semantic knowledge in the presence of relatively preserved other cognitive skills. Recent treatment studies have proven that language rehabilitation aimed at anomia in semantic dementia can be successful. The objective of this study was to examine the separate and interactive effects of errorless vs. errorful and active vs. passive learning approaches to anomia and their effects on naming and comprehension of treated items, as well as maintenance and generalisation of treatment gains. Seven participants with semantic dementia re-learned two sets of words (one for which participants retained auditory comprehension, and one for which they did not) in each of four different treatment methods based on those approaches. Errorless learning proved more successful than errorful learning in restoring lexical representations in all but one participant while there was no interaction between effects of errorless and active approaches on treatment success. Maintenance of treatment gains showed an advantage for errorless learning at one but not three months post-treatment, although all overall gains were maintained to a significant degree at both time points. Effects of both treatment and maintenance were stronger for items for which participants showed preserved auditory comprehension. The results are discussed in a framework of progressive language disorders and applicability of errorless methods to language rehabilitation in semantic dementia.

Relearning in semantic dementia reflects contributions from both medial temporal lobe episodic and degraded neocortical semantic systems: evidence in support of the complementary learning systems theory.

When relearning words, patients with semantic dementia (SD) exhibit a characteristic rigidity, including a failure to generalise names to untrained exemplars of trained concepts. This has been attributed to an over-reliance on the medial temporal region which captures information in sparse, non-overlapping and therefore rigid representations. The current study extends previous investigations of SD relearning by re-examining the additional contribution made by the degraded cortical semantic system. The standard relearning protocol was modified by careful selection of foils to show that people with semantic dementia were sometimes able to extend their learning appropriately but that this correct generalisation was minimal (i.e. the patients under-generalised their learning). The revised assessment procedure highlighted the fact that, after relearning, the participants also incorrectly over-generalised the learned label to closely related concepts. It is unlikely that these behaviours would occur if the participants had only formed sparse hippocampal representations. These novel data build on the notion that people with semantic dementia engage both the degraded cortical semantic (neocortex) and the episodic (medial temporal) systems to learn. Because of neocortical damage to the anterior temporal lobes, relearning is disordered with a characteristic pattern of under- and over-generalisation.

Cooking "shrimp à la créole": a pilot study of an ecological rehabilitation in semantic dementia.

New learning in semantic dementia (SD) seems to be tied to a specific temporal and spatial context. Thus, cognitive rehabilitation could capitalise upon preserved episodic memory and focus on everyday activities which, once learned, will have an impact in everyday life. This pilot study thus explores the effectiveness of an ecological approach in one patient suffering from SD. EC, a 68-year-old woman with SD, stopped cooking complex meals due to a substantial loss of knowledge related to all food types. The therapy consisted of preparing a target recipe. She was asked to generate semantic attributes of ingredients found in one target, one control and two no-therapy recipes. The number of recipes cooked by EC between therapy sessions was computed. She was also asked to prepare a generalisation recipe combining ingredients from the target and control recipes. EC's generated semantic attributes (GSA) of ingredients pertaining to the target and control recipes increased significantly (p < .001), compared to the no-therapy recipes (ps > .79). The proportion of meals cooked also increased significantly (p = .021). For the generalisation recipe, she could not succeed without assistance. Frequent food preparation may have provided EC with new memories about the context, usage and appearance of some concepts. These memories seem very context-bound, but EC nonetheless re-introduced some recipes into her day-to-day life. The impact of these results on the relationship between semantic, episodic and procedural memory is discussed, as well as the relevance of an ecological approach in SD.

Errorless learning of computer-generated words in a patient with semantic dementia.

This study explores the effectiveness and feasibility of an errorless learning approach administered via a computer-based treatment for anomia to CS, an individual with semantic dementia. Using a multiple baseline across behaviours design, we explored treatment specific effects, maintenance and generalisation of gains derived from the MossTalk Words((R)) therapy programme. CS was treated on three lists of words, each containing items for which CS retained some semantic knowledge and some for which he did not. CS was tested immediately after therapy, and one and three months later. Improved naming was maintained on all lists at all testing intervals. In addition, among those words for which CS retained some semantic knowledge, he maintained the ability to name all practised words, but only half of the not practised words. This study underscored the feasibility of computer-based treatments for anomia in progressive disorders, demonstrated the effectiveness of an errorless approach in semantic dementia in re-training lost words, and provided justification for training words that patients still have in their daily vocabulary. The results are discussed in relation to other treatment studies in progressive aphasia and in the context of factors necessary for therapeutic success in semantic dementia.