Long-term maintenance of novel vocabulary in persons with chronic aphasia

Background: The study of novel word learning in aphasia can shed light on the functionality of patients' learning mechanisms and potentially help in treatment planning. Previous studies have indicated that persons with aphasia are able to learn some new vocabulary. However, these learning outcomes appear short-lived and evidence for the ability to use the newly learned words in the long term is lacking.

Aims: Participants with aphasia and matched controls underwent short training where they were taught to name novel objects with novel names. We studied the participants' word learning and particularly their long-term maintenance. We also examined whether the language and verbal short-term memory impairments of the participants with aphasia related to their ability to acquire and maintain phonological and semantic information on novel words.

Methods & Procedures: Two participants with nonfluent aphasia, LL and AR, and two matched controls took part in the experiment. They were taught to name 20 unfamiliar objects by repeating the names in the presence of the object picture. Half of the items carried a definition that was used to probe incidental semantic learning. There were four training sessions, a post-training test, and follow-up tests up to 6 months post-training. Learning measures included recognition of the trained objects, as well as spontaneous and cued recall in visual confrontation naming. Incidental semantic learning was measured by spontaneous recall of the definitions.

Outcomes & Results: Combining spontaneous and phonologically cued responses, LL acquired 70% and AR 55% of the novel words. With phonological cueing, LL named 50% of the items correctly up to 6 months post-training (vs 95–100% for the controls) and AR 25% up to 8 weeks post-training. AR's lexical-semantic processing, pseudoword repetition and verbal short-term capacity were inferior to those of LL. In line with this, AR learned fewer words and showed more decline in recognition memory for the trained items, and weaker recall of the semantic definitions.

Conclusions: Our results support previous findings that people with aphasia can learn to name novel items. More importantly, the results show for the first time that, with phonological cueing, an individual with aphasia can maintain some of this learning up to 6 months post-training. Moreover the results provide further evidence for the significance of the functional status of lexical-semantic processing on word learning success.     

Relearning and retention of verbal labels in a case of semantic dementia

Background: Previous studies looking at relearning and retention of word labels in people with semantic dementia have shown some improvement in naming immediately after the period of learning but this has not usually been maintained. Studies have also shown rigid learning of names, in the order of presentation and to the picture exemplars only, with no generalisation of learning.

Aims: This study aimed to explore relearning of a small vocabulary set in a person with semantic dementia (CUB) and to examine her ability to generalise this learning. In addition, it aimed to find out how long the learning persisted after therapy was completed given that semantic dementia is a progressive disorder.

Methods & Procedures: A single‐case design was used where CUB was asked to learn 28 words while a further 28 were left as controls. A “look and say” method was used daily for 1 month. As well as examining learning of the therapy and control set, CUB was asked to name 168 other exemplars of the learning set to see whether there had been any transfer of her learning from the therapy set.

Outcomes & Results: CUB not only relearned a set of picture names but retained these without deliberate practice over a 6‐month period. She was also able to generalise this learning to other visually similar exemplars in testing and in daily use. The maintenance of relearning was achieved despite severe deterioration in her semantic memory.

Conclusions: Possible reasons are explored as to why CUB was able to relearn and retain these words and why this may differ from all previously reported cases. Differences in amount of time spent relearning, number of items learned, therapy methods, the severity of semantic memory impairment, the degree of atrophy, and the behavioural profiles of people with semantic dementia do not provide adequate explanations for our individual's differential ability to retain her learning over 6 months. The most plausible explanation is that the person with semantic dementia generalised her learning to her everyday speech and this provided the source of maintenance for the relearned names.     

New word learning in people with aphasia

Background: The theory of speech and language therapy intervention for people with aphasia is still under‐articulated, and some people with aphasia respond better to therapy than others. The reasons for individual variation in response to therapy have not yet been fully established but may partially reflect a person with aphasia's ability to utilise a range of cerebral mechanisms, such as re‐accessing damaged neural pathways and establishing new ones. Most current therapies aim to help the person with aphasia access their previously available language abilities. New learning may offer an alternative therapy approach. However, there is little evidence to date on the effect of aphasia on a person's capability to learn new linguistic information.

Aim: To explore the new vocabulary learning potential of people with aphasia.

Methods & Procedures: Twelve participants, under the age of 65 years and with a range of aphasia severity and personal backgrounds, were taught 20 novel words over four consecutive days. Their learning of this new vocabulary was measured via a range of single‐word processing tasks based on the cognitive neuropsychological model. Ten participants repeated the tasks a few days later to establish whether the new vocabulary had been retained in long‐term memory.

Outcomes & Results: All of the participants demonstrated some ability to learn the new vocabulary (both novel word forms and novel word meanings), with scores ranging from 15% to 99% on the various assessments. At the follow‐up session, the ten participants retained between 49% and 83% of their previous scores.

Conclusions: This study has important implications for aphasia rehabilitation as it has shown that people with aphasia have the potential to learn new linguistic material, even in the presence of severe language impairments. This capacity could be exploited in therapy. Previously known words could be taught as new. Pre‐therapy assessment of the person with aphasia's learning capacity and style would promote individually‐tailored learning experiences and so, potentially, more effective therapy and better clinical outcomes.     

Effectiveness of a vocabulary data file,encyclopaedia, and Internet homepages in a conversation‐support system for people with moderate‐to‐severe aphasia

Background: In order to facilitate conversation for people with moderate‐to‐severe aphasia, a conversation‐support system has been developed. This system consists of three electronic resources: a vocabulary data file, an encyclopaedia, and homepages on the Internet. The vocabulary data file we created contains approximately 50,000 words, mostly consisting of various proper names, which are classified into 10 categories. These words function as keywords in conversation.

Aims: To evaluate the effectiveness of the three resources in eliciting new information from people with aphasia.

Methods & Procedures: Fifteen people with non‐fluent and moderate‐to‐severe aphasia participated in the experiment. Participants conversed with their communication partners about four topics under use and non‐use conditions. Under the use condition, partners showed pages from one of the three resources on the screen of a personal computer. Participants were asked to select words on the pages, or use other modalities (verbal or nonverbal), to answer questions. Three evaluators gave points for information conveyed correctly.

Outcomes & Results: Comparison of the points between the use and non‐use conditions showed that significantly more information was conveyed when the vocabulary data file was used. On the other hand, the amount of points did not increase in the use condition using the encyclopaedia or homepages.

Conclusions: The vocabulary date file succeeded in eliciting more information from people with moderate‐to‐severe aphasia within a limited timeframe. Presentation of the keyword or proper name lists related to the topics was shown to be a useful conversation resource for people with moderate‐to‐severe aphasia. As for the encyclopaedia and homepages, further research is required to determine whether or not these resources in collaboration with the data file can further facilitate conversation.     

A contextual approach to facilitating word retrieval in agrammatic aphasia

Background: Although virtually all individuals with aphasia demonstrate problems with word retrieval, this symptom might arise for different reasons in individuals with different types of aphasia. A trade‐off of dependence on semantic and syntactic information is hypothesised to underlie dissociations in word retrieval shown by fluent anomic and non‐fluent agrammatic speakers. This division of labour predicts that strengthening semantic input will improve word retrieval for those with anomic aphasia, whereas strengthening syntactic input through contextual cues will improve word retrieval for those with agrammatic aphasia.

Aims: To explore the outcome of a new treatment approach that proposes to improve word retrieval in individuals with agrammatic aphasia by implicitly strengthening the links between target words and associated words which co‐occur in a connected speech context.

Methods & Procedures: The outcomes of two therapy approaches were examined in two participants with agrammatic aphasia. One therapy approach focused on explicitly training semantic features of target words; the other, more novel, approach focused on implicitly strengthening contextual associations through story telling and retelling. It was predicted that the latter approach would result in greater benefits for the two agrammatic participants.

Outcomes & Results: Although both therapy approaches appeared to be effective, the predicted advantage of the contextually based approach was not found. The evolution of the error patterns throughout the treatment was examined to help understand the mechanisms underlying the improvements shown for each participant.

Conclusions: A novel treatment involving training words in a story context was shown to result in improved word retrieval for two participants with agrammatic aphasia. The merits of the approach are discussed, relative to more traditional explicit word retrieval therapy approaches.     

A meta-analysis of word-finding treatments for aphasia

Background: The research literature on treatment methods for word-finding deficits in aphasia is extensive. A meta-analysis of studies for word-finding therapy was conducted in order to objectively synthesise this information to answer large-scale questions of treatment efficacy.

Aims: The purpose of this study was to examine the efficacy of various treatment approaches for word-finding deficits for individuals with aphasia. This analysis also examined gains made to trained and untrained words, the level of maintenance after therapy, and the effect of the time post-onset of aphasia on the recovery of language function.

Methods & Procedures: Various search methods were used to gather anomia treatment studies for this analysis. From 44 studies, 107 effect sizes were calculated for the final analysis. These data were sorted according to the following moderator variables: treatment category (semantic, phonological, or mixed), word set (trained, exposed-related, exposed-unrelated, unexposed-unrelated, and unexposed-related), follow-up measures, and median number of months post-onset.

Outcomes & Results: All therapy approaches showed evidence of efficacy, although the variance between studies was large. Strong gains were seen for trained and exposed words, but only minor gains for unexposed words. Large effects were seen for up to 2 months post-therapy, with lingering effects at 3 months post-therapy. Treatment appeared efficacious even for individuals that were years post-onset.

Conclusions: An objective synthesis of the literature shows that intervention for word-finding deficits is efficacious. However, the level of gains varied widely across studies and therapy approaches. As expected, little generalisation was found for untrained-unexposed words.     

Dynamic-intentional thalamic aphasia: a failure of lexical-semantic self-activation

Background: Previous research has described patients with aphasia from thalamic lesions, some of whom were non-fluent with intact comprehension, others who were fluent with impaired comprehension, and some of whom are non-fluent with impaired comprehension. Whereas these three subtypes usually have normal repetition, they had impaired naming, suggesting a deficit in lexical (phonological word forms)-semantic processing. We report a patient with a left thalamic hemorrhage in which lexical-semantic representations appear to be intact but the patient demonstrates an inability to spontaneously activate his lexical-semantic system Methods: A 82-year-old, right-handed man presented with decreased verbal fluency and memory loss following a thalamic hemorrhage. Neuropsychological assessment revealed significant decrements in verbal fluency with intact naming, comprehension, repetition and vocabulary. Conclusions: To the best of our knowledge this pattern of language disturbance, which mirrors dynamic aphasia induced by frontal lesions, has not previously been described with thalamic injury. The thalamus has strong connections with the frontal lobe and rather than degradation of lexical-semantic representations, this patient's thalamic lesion probably induced frontal lobe dysfunction with a failure to spontaneously active lexical semantic representations.     

Learning and forgetting new names and objects in MCI and AD

We studied how subjects with mild cognitive impairment (MCI), early Alzheimer's disease (AD) and age-matched controls learned and maintained the names of unfamiliar objects that were trained with or without semantic support (object definitions). Naming performance, phonological cueing, incidental learning of the definitions and recognition of the objects were tested during follow-up. We found that word learning was significantly impaired in MCI and AD patients, whereas forgetting patterns were similar across groups. Semantic support showed a beneficial effect on object name retrieval in the MCI group 8 weeks after training, suggesting that the MCI patients’ preserved semantic memory can compensate for impaired episodic memory. The MCI group performed equally well as the controls in the tasks measuring incidental learning and recognition memory, whereas the AD group showed impairment in this respect. Both the MCI and the AD group benefited less from phonological cueing than the controls. Our findings indicate that word learning is compromised in both MCI and AD, whereas long-term retention of newly learned words is not affected to the same extent. Incidental learning and recognition memory seem to be well preserved in MCI.     

Phonological short-term memory in conduction aphasia

Background: Within cognitive neuropsychological models conduction aphasia has been conceptualised as a phonological buffer deficit. It may affect the output buffer, the input buffer, or both. The phonological output buffer is a short-term storage, responsible for the short-term maintenance of phonological units until their articulation, as well as for phonological and morphological composition. The phonological input buffer holds input strings until they are identified in the input lexicon. Thus the phonological buffers are closely related to phonological short-term memory (pSTM), and hence it is important to assess pSTM in conduction aphasia. Because the input and output buffers play different roles, impairment in each of them predicts different impairments in the patient's ability to understand certain sentences, to learn new words and names, and to remember and recall lists of words and numbers for short time periods.

Aims: This study explored in detail pSTM in individuals with conduction aphasia, comparing individuals with input and output deficits, recall and recognition tasks, and stimuli of various types. It also tested pSTM in six age groups of healthy individuals, assessing the effect of age on various types of stimuli. This paper presents a new battery of 10 recall and recognition span tests, designed to assess pSTM in aphasia and to measure spans and effects on spans.

Methods & Procedures: The participants were 14 Hebrew-speaking individuals with conduction aphasia, 12 with input or input-output phonological buffer deficit, and 2 with only output deficit, and 296 healthy individuals.

Outcomes & Results: The analyses of the spans and effects on pSTM in the 10 tests indicated that all the participants with conduction aphasia had limited pSTM, significantly poorer than that of the control participants, and no semantic STM impairment. They had shorter spans, smaller length and similarity effects, and larger sentential effect than the controls. The individuals with conduction aphasia who had an impairment in the phonological input buffer showed deficit in both the recall and recognition span tasks. The individuals with the output conduction aphasia showed impairment only in the recall tasks. The healthy individuals showed age effect on span tasks involving words, but no effect of age on span tasks of nonwords.

Conclusions: pSTM is impaired in conduction aphasia, and different pSTM impairments characterise different types of conduction aphasia. Output conduction aphasia causes difficulties only when verbal output is required, whereas input conduction aphasia also causes a deficit when only recognition is required. This suggests that rehearsal can take place without the phonological output buffer. Age differentially affects pSTM for words and nonwords in healthy adults: whereas the encoding of words changes, the ability to remember nonwords is unchanged.     

Lexical-semantic representation in bilingual aphasia: Findings from semantic priming and cognate repetition priming

Background: While many studies have investigated the nature of language organisation in monolingual speakers with aphasia, our understanding of bilingual aphasia lags far behind. Only a handful of studies have employed on-line psycholinguistic experimental methods to explore the nature of language representation and processing in bilingual speakers with aphasia. Improving our understanding of how language is organised and processed in bilingual speakers with aphasia is central to the development of effective impairment-level language treatments. Cognate/noncognate representation and semantic representation are two key aspects of bilingual language organisation that are yet to be explored in depth in bilingual speakers with aphasia.

Aims: The present study aimed to investigate (1) whether semantic representation was shared across the two languages of a bilingual speaker with aphasia and (2) whether cognate words would produce a processing advantage relative to noncognate words (as has been found in neurologically-normal younger bilingual adults).

Methods & Procedures: A 70-year-old bilingual Italian/English speaker, who presented with nonfluent aphasia and apraxia of speech, completed two priming experiments: a semantic priming experiment and a cognate repetition priming experiment.

Outcomes & Results: In the semantic priming experiment, the participant demonstrated large priming effects in both within-language conditions and one cross-language condition. The finding of priming in at least one of the cross-language conditions provides some corroboration for shared semantic representation in this bilingual individual with aphasia. In the cognate repetition priming experiment, the participant produced a language-specific cognate advantage in English, for words repeated in the same language. For words repeated in a different language condition (i.e., as their translation equivalent), the participant produced a processing advantage for noncognate words.

Conclusions: The findings of this study provided support for shared semantic representation in bilingual speakers following aphasia; however, the results also suggested that aphasia can disrupt normal lexical access processes. Results in relation to cognate versus noncognate processing suggested that bilingual speakers with aphasia may not, necessarily, always display a cognate advantage. Overall, the present study showed that language processing in bilingual speakers with aphasia is highly complex and is dependent upon the intricate interplay between the speaker’s premorbid language proficiency, inhibitory processing deficits that occur with normal aging and postmorbid language impairment and recovery patterns.     

Functionally relevant items in the treatment of aphasia (part II): Further perspectives and specific tools

Background: This paper is the second in a two part series. In part I, we reviewed the concept of “functionally relevant” and the strategies underlying identification of such vocabulary items for aphasia treatment. Based on the review, we concluded that there is a lack of definitions, strategies and specific tools to assist with identification of functionally relevant items for aphasia therapy. We suggested that frequency-based vocabulary lists could and should be used to increase the number of potentially relevant items in aphasia therapy and that therapy should be directed to words other than the most concrete nouns and verbs.

Aims: This article reviews the existing strategies and materials from adjacent fields relating to functionally relevant stimuli with the aim of establishing resources for identifying potentially relevant therapy items at the level of both vocabulary items and topics of conversation.

Main contribution: By reviewing the core concepts and research from other fields, this article brings together knowledge and materials that can improve current practice regarding identification of functionally relevant items in aphasia therapy. The focus of the review is on studies that have been published in the field of augmentative and alternative communication (AAC) and research that has provided information on unimpaired and impaired adult speakers’ everyday conversations. By reanalysing data sets from these studies and using a large psycholinguistic database, we present four resources. Two of the data sets provide evidence regarding the most frequent topics of conversation; one is based on unimpaired speakers conversations and the other extends this by including information from both unimpaired and aphasic speakers’ topics of conversation. In addition, to provide evidence of the most frequent vocabulary in adult conversations, we present a list of words compiled from three separate data sets. Finally, a vocabulary list of the 1000 most frequent words retrieved from an objective frequency count (SUBTLEX-US) is presented. Together these resources provide a means for clinicians to select objectively frequent topics and vocabulary as stimuli for functionally relevant therapy.

Conclusions: The agenda for future research is to identify specific vocabulary within the most common topics of conversation. The resources provided as part of this article serve as a first step towards the ultimate goal of enabling clinicians to select stimuli for therapy in a more systematic, transparent and objective way.     

The role of semantic knowledge in relearning spellings: Evidence from deep dysgraphia

Background: Remediation techniques for dysgraphia have focused on targeting different components of the theoretical models for spelling. Studies have revealed that targeting lexically oriented strategies can prove beneficial for patients with deep dysgraphia. Studies on short‐term memory have also demonstrated a role of semantic knowledge in short‐term retention

Aims: Two variants of lexically oriented strategies were applied to remediate a deep dysgraphic patient, PH, and the role of imagery in supporting the learning was examined.

Methods & Procedures: Retraining was explored using a visual‐kinaesthetic learning technique, contrasting performance with high‐ and low‐imagery words.

Outcomes & Results: Positive effects of learning were demonstrated. There was effective initial learning of blocks of both high‐imagery and low‐imagery target words, but high‐imagery words had a clear advantage in terms of longer‐term maintenance.

Conclusions: The data demonstrate that semantic knowledge may play a role in strengthening graphemic representations of words, helping in the maintenance of the orthography of target words over time.     

Processing proper nouns in aphasia: Evidence from assessment and therapy

Background: Dissociations between proper and common names following brain damage have frequently been reported (see Yasuda, Nakamura, & Beckman, 2000, for review) and suggest that these different word classes are processed by distinct mechanisms. The dissociations are often observed in people with relatively pure impairments, but might also be expected more generally in aphasia. There is the further possibility that the different vocabulary groups require different therapy approaches. Yet, to our knowledge, no study has explored whether treatments that are known to be successful with common nouns are also successful with proper nouns. Aims: This study had two main aims: to compare the comprehension and production of common and proper nouns in 20 people with aphasia; and to investigate whether semantic naming therapy is equally effective for common and proper nouns. Methods & Procedures: A total of 20 people with aphasia were tested in their ability to comprehend and produce matched sets of proper and common nouns. The stimuli comprised: 20 famous people, 20 famous places, 20 high‐familiarity common nouns, and 20 low‐familiarity common nouns. Participants were also tested with personally relevant proper names, such as the names of family members. In the second phase of the study 10 of the original participants were given semantic therapy for both common and proper nouns. Experimental measures explored effects on treated and untreated words. Outcomes & Results: Initial testing found that comprehension scores were generally high, with no word class effect. In production, proper nouns were significantly more difficult to name than the matched common nouns. However, this finding excluded personally relevant proper nouns, which were the most successfully named items. Results from the second phase showed that semantic therapy was equally effective in improving naming of both common and proper nouns. As in many previous studies, effects were almost entirely confined to treated items. Conclusions: Our findings suggest that proper nouns induce more naming failures in aphasia than common nouns. However, despite this, they seem equally amenable to therapy. Clinical and theoretical implications are discussed.     

Morphological decomposition in Broca’s aphasia

Background: Few studies have investigated how individuals diagnosed with post-stroke Broca’s aphasia decompose words into their constituent morphemes in real-time processing. Previous research has focused on morphologically complex words in non-time-constrained settings or in syntactic frames, but not in the lexicon.

Aims: We examined real-time processing of morphologically complex words in a group of five Greek-speaking individuals with Broca’s aphasia to determine: (1) whether their morphological decomposition mechanisms are sensitive to lexical (orthography and frequency) vs. morphological (stem-suffix combinatory features) factors during visual word recognition, (2) whether these mechanisms are different in inflected vs. derived forms during lexical access, and (3) whether there is a preferred unit of lexical access (syllables vs. morphemes) for inflected vs. derived forms.

Methods & Procedures: The study included two real-time experiments. The first was a semantic judgment task necessitating participants’ categorical judgments for high- and low-frequency inflected real words and pseudohomophones of the real words created by either an orthographic error at the stem or a homophonous (but incorrect) inflectional suffix. The second experiment was a letter-priming task at the syllabic or morphemic boundary of morphologically transparent inflected and derived words whose stems and suffixes were matched for length, lemma and surface frequency.

Outcomes & Results: The majority of the individuals with Broca’s aphasia were sensitive to lexical frequency and stem orthography, while ignoring the morphological combinatory information encoded in the inflectional suffix that control participants were sensitive to. The letter-priming task, on the other hand, showed that individuals with aphasia—in contrast to controls—showed preferences with regard to the unit of lexical access, i.e., they were overall faster on syllabically than morphemically parsed words and their morphological decomposition mechanisms for inflected and derived forms were modulated by the unit of lexical access.

Conclusions: Our results show that in morphological processing, Greek-speaking persons with aphasia rely mainly on stem access and thus are only sensitive to orthographic violations of the stem morphemes, but not to illegal morphological combinations of stems and suffixes. This possibly indicates an intact orthographic lexicon but deficient morphological decomposition mechanisms, possibly stemming from an underspecification of inflectional suffixes in the participants’ grammar. Syllabic information, however, appears to facilitate lexical access and elicits repair mechanisms that compensate for deviant morphological parsing procedures.     

How to constrain and maintain a lexicon for the treatment of progressive semantic naming deficits: Principles of item selection for formal semantic therapy

The progressive degradation of semantic memory is a common feature of many forms of dementia, including Alzheimer's disease and the semantic variant of primary progressive aphasia (svPPA). One of the most functionally debilitating effects of this semantic impairment is the inability to name common people and objects (i.e., anomia). Clinical management of a progressive, semantically based anomia presents extraordinary challenges for neurorehabilitation. Techniques such as errorless learning and spaced-retrieval training show promise for retraining forgotten words. However, we lack complementary detail about what to train (i.e., item selection) and how to flexibly adapt the training to a declining cognitive system. This position paper weighs the relative merits of several treatment rationales (e.g., restore vs. compensate) and advocates for maintenance of known words over reacquisition of forgotten knowledge in the context of semantic treatment paradigms. I propose a system for generating an item pool and outline a set of core principles for training and sustaining a micro-lexicon consisting of approximately 100 words. These principles are informed by lessons learned over the course of a Phase I treatment study targeting language maintenance over a 5-year span in Alzheimer's disease and SvPPA. Finally, I propose a semantic training approach that capitalises on lexical frequency and repeated training on conceptual structure to offset the loss of key vocabulary as disease severity worsens.     

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^® 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.     

Verbal learning in semantic dementia: Is repetition priming a useful strategy?

Background: Semantic dementia (SD) is a neurodegenerative disease that impacts long-term conceptual and lexical knowledge (Hodges & Patterson, 1996). Severe naming difficulties are prevalent in SD, yet little is known about the potential for word learning in this population.Aims: We assessed patterns of repetition and implicit learning in patients with moderate to advanced SD via repeated exposure to word lists varied by frequency and imageability. We propose a tentative framework for the language loss incurred in SD and open a dialogue for treatment approaches targeted towards progressive semantic anomia.Methods and Procedures: In two experiments, we examined immediate serial recall and short-term learning in five patients with SD. We predicted reduced semantic effects (imageability), preservation of lexical effects (frequency), and diminished primacy effects in serial recall, consistent with other semantically impaired populations (Martin & Saffran, 1997). We also predicted that severity of semantic impairment would modulate the facilitative effects of repeated exposure (i.e., repetition priming) on word list recall.Outcomes and Results: In immediate serial recall, all participants showed reduced imageability effects, but only one patient showed a significant word frequency advantage. Two patterns of serial position effects emerged: (1) poor recall of initial list items and (2) better recall of initial and final items. All participants showed minimal gains across repeated trials; however, patients who poorly recalled initial items showed the least benefit from repeated exposure.Conclusions: We discuss the usefulness of repetition-based interventions for SD and advocate maintenance of known vocabulary over reacquisition of forgotten words. We provide a theoretical framework for progressive language loss associated with SD; this model reflects an ordered reduction of lexical-semantic support coinciding with dementia severity.     

A proposed reinterpretation and reclassification of aphasic syndromes

Background: Different classifications of aphasic disorders have been proposed over the years. During recent decades new approaches to aphasia study have been developed, suggesting that current aphasia classifications can and should be reconsidered.

Aims: The purpose of this paper is to attempt to integrate contemporary knowledge about brain organisation of language and to propose a new aphasia classification.

Main Contribution: It is emphasised that there are two fundamental forms of aphasia, which are linked to impairments in the lexical/semantic and grammatical systems of language (Wernicke‐type aphasia and Broca‐type aphasia, respectively). Grammar correlates with the ability to represent actions (verbs) and depends on what is known as Broca's area and its related brain circuits, but it is also related to the ability to quickly carry out the sequencing of articulatory movements required for speaking (speech praxis). Lexical/semantic and grammatical systems not only depend on different brain circuitries, but also on different types of memory and learning (declarative and procedural). Other aphasic syndromes do not really impair language knowledge per se, but rather peripheral mechanisms required to produce language (conduction aphasia and aphasia of the supplementary motor area), or the executive control of the language (extra‐Sylvian or transcortical motor aphasia).

Conclusions: A new classification of aphasic syndromes is proposed: primary (or “central”) aphasias (Wernicke's aphasia—three subtypes—and Broca aphasia); secondary (or “peripheral”) aphasias (conduction aphasia and supplementary motor area aphasia); and dysexecutive aphasia (extra‐Sylvian—transcortical—motor aphasia), are distinguished.     

Effect of familiar content on paragraph comprehension in aphasia

Background: Previous research has shown that context improves aphasic individuals' auditory comprehension. The specific contextual information that has been identified as beneficial includes semantic constraints, semantic plausibility, both predictive and non‐predictive information, and familiar topics. However, context can also include familiar content such as the names of relatives, friends, local schools, and local stores.

Aims: The purpose of the present study was to assess the influence of familiar content on comprehension in individuals with aphasia. Specifically, it assessed whether individuals with aphasia answer questions about paragraphs more accurately when the paragraphs contain familiar content than when they do not.

Methods & Procedures: Eleven participants with aphasia and eleven participants without brain damage listened to short paragraphs that differed in the familiarity of the content included. In half of the paragraphs, the people and places were generic and not known specifically by the participants. In the other half, the people and places were known by the participants (as provided by a spouse or other close individual). Approximately half of the subsequent questions asked of the participants related to this targeted information and half related to other, more generic, information in the paragraphs.

Outcomes & Results: The questions relating to the paragraphs with the familiar content were answered more accurately than were the questions relating to the paragraphs with neutral content. For the participants with aphasia, this result occurred for the questions relating to both the targeted (and thus familiar) information and the non‐targeted or neutral information. The extent to which each participant with aphasia benefited from the familiar content did not relate to age, education, time‐post‐onset, or comprehension and naming skills.

Conclusions: These results suggest that familiar content may be another type of context that enhances comprehension skills in individuals with aphasia. The results are interpreted with respect to attention and domain knowledge concepts.     

Lexicality effects in word and nonword recall of semantic dementia and progressive nonfluent aphasia

Background: Verbal working memory is an essential component of many language functions, including sentence comprehension and word learning. As such, working memory has emerged as a domain of intense research interest both in aphasiology and in the broader field of cognitive neuroscience. The integrity of verbal working memory encoding relies on a fluid interaction between semantic and phonological processes. That is, we encode verbal detail using many cues related to both the sound and meaning of words. Lesion models can provide an effective means of parsing the contributions of phonological or semantic impairment to recall performance.

Methods & Procedures: We employed the lesion model approach here by contrasting the nature of lexicality errors incurred during recall of word and nonword sequences by three individuals with progressive nonfluent aphasia (a phonological dominant impairment) compared to that of two individuals with semantic dementia (a semantic dominant impairment). We focused on psycholinguistic attributes of correctly recalled stimuli relative to those that elicited a lexicality error (i.e., nonword → word OR word → nonword).

Outcomes & Results: Patients with semantic dementia showed greater sensitivity to phonological attributes (e.g., phoneme length, wordlikeness) of the target items relative to semantic attributes (e.g., familiarity). Patients with PNFA showed the opposite pattern, marked by sensitivity to word frequency, age of acquisition, familiarity, and imageability.

Conclusions: We interpret these results in favour of a processing strategy such that in the context of a focal phonological impairment patients revert to an over-reliance on preserved semantic processing abilities. In contrast, a focal semantic impairment forces both reliance on and hypersensitivity to phonological attributes of target words. We relate this interpretation to previous hypotheses about the nature of verbal short-term memory in progressive aphasia.