Irene Minkina

Short-Term Memory and Aphasia: From Theory to Treatment

Abstract This article reviews existing research on the interactions between verbal short‐term memory and language processing impairments in aphasia. Theoretical models of short‐term memory are reviewed, starting with a model assuming a separation between short‐term memory and language, and progressing to models that view verbal short‐term memory as a cognitive requirement of language processing. The review highlights a verbal short‐term memory model derived from an interactive activation model of word retrieval. This model holds that verbal short‐term memory encompasses the temporary activation of linguistic knowledge (e.g., semantic, lexical, and phonological features) during language production and comprehension tasks. Empirical evidence supporting this model, which views short‐term memory in the context of the processes it subserves, is outlined. Studies that use a classic measure of verbal short‐term memory (i.e., number of words/digits correctly recalled in immediate serial recall) as well as those that use more intricate measures (e.g., serial position effects in immediate serial recall) are discussed. Treatment research that uses verbal short‐term memory tasks in an attempt to improve language processing is then summarized, with a particular focus on word retrieval. A discussion of the limitations of current research and possible future directions concludes the review.

An investigation of aphasic naming error evolution following phonomotor treatment

Background: Though treatments for anomia in aphasia typically use accuracy of trained and untrained targets to determine treatment efficacy, researchers have begun to employ error analyses in order to more closely delineate the mechanisms involved in anomia recovery. Aims: The aim of this study was to examine changes in naming errors of 24 individuals with aphasia after phonomotor treatment (14 new individuals and 10 individuals whose word retrieval error data were previously reported in a separate manuscript). Methods & Procedures: Twenty-four individuals with aphasia received phonomotor treatment. Confrontation naming was assessed pre-treatment, immediately post-treatment, and 3 months post-treatment. Responses were scored for accuracy and error type. Paired-samples t tests comparing pre-treatment versus immediately post-treatment and 3 months post-treatment accuracy and error-type proportions were conducted. Additionally, the role of language severity in error-type proportion shifts was examined through analyses of subgroups and correlational analyses between language measures and error-type change scores. Outcomes & Results: Trained and untrained naming accuracy improved significantly immediately post-treatment, and gains were maintained 3 months post-treatment. No significant changes in error-type proportions were noted; however, trends towards decreases in proportions of omissions were noted immediately post-treatment (trained items) and 3 months post-treatment (trained and untrained items). In a post hoc subgroup analysis, a significant decrease in the proportion of omissions on trained items was noted 3 months post-treatment for the subgroup of individuals with lower lexical retrieval ability. Conclusions: Results are indicative of a shift in linguistic processing in which the linguistic network was holistically altered as a result of phonomotor treatment.

Assessment of linguistic and verbal short-term memory components of language abilities in aphasia

Some current models of aphasia emphasize a role of short-term memory in the processing of language and propose that the language impairment in aphasia involves impairment to cognitive processes that activate and maintain representations of words over the time-period needed to support single word and multiple word tasks, including verbal span tasks. This paper reports normative data from 39 people with aphasia and 16 age-matched neurotypical controls on a test battery for aphasia that assesses effects of increased short-term/working memory load on word and sentence processing as well as effects of linguistic variations on verbal short-term memory abilities Two concepts are discussed that capture the unique potential of this test battery for research and clinical practice: specificity of diagnosis and sensitivity to all degrees of aphasia severity, including mild aphasia. An analysis is included that shows how the performance of individuals with mild aphasia who achieve normal level of performance on the Western Aphasia Battery (Kertesz, 2006) show a decline in a temporal delay condition that is greater than performance of control participants. We also report preliminary data showing differential effects of adding a time interval before a response or between items to be compared: reduced accuracy for some individuals with aphasia and improved accuracy for others. The theoretical and clinical importance of this finding is discussed, as well as the overall potential for this test battery to be used in research and as a clinical tool. Finally, we discuss the relevance of this test battery to investigate functional communication abilities in aphasia.

Influence of Linguistic and Nonlinguistic Variables on Generalization and Maintenance Following Phonomotor Treatment for Aphasia

Purpose Although phonomotor treatment shows promise as an effective intervention for anomia in people with aphasia, responses to this treatment are not consistent across individuals. To better understand this variability, we examined the influence of 5 participant characteristics-age, time postonset, aphasia severity, naming impairment, and error profile-on generalization and maintenance of confrontation naming and discourse abilities following phonomotor treatment. Method Using retrospective data from 26 participants with aphasia who completed a 6-week phonomotor treatment program, we examined the relationships between participant characteristics of interest and change scores on confrontation naming and discourse tasks, measured pretreatment, immediately following treatment, and 3 months following treatment. Results Although the participant characteristics of aphasia severity and error profile appeared to predict generalization to improved confrontation naming of untrained items and discourse performance, a post hoc analysis revealed that no one characteristic predicted generalization across participants at 3 months posttreatment. Conclusions Response to phonomotor treatment does not appear to be influenced by aphasia and anomia severity level, error profile, participant age, or time postonset. Other factors, however, may influence response to intensive aphasia treatment and are worthy of continued exploration.

Links Between Short-Term Memory and Word Retrieval in Aphasia

Purpose This study explored the relationship between anomia and verbal short-term memory (STM) in the context of an interactive activation language processing model. Method Twenty-four individuals with aphasia and reduced STM spans (i.e., impaired immediate serial recall of words) completed a picture-naming task and a word pair repetition task (a measure of verbal STM). Correlations between verbal STM and word retrieval errors made on the picture-naming task were examined. Results A significant positive correlation between naming accuracy and verbal span length was found. More intricate verbal STM analyses examined the relationship between picture-naming error types (i.e., semantic vs. phonological) and 2 measures of verbal STM: (a) location of errors on the word pair repetition task and (b) imageability and frequency effects on the word pair repetition task. Results indicated that, as phonological word retrieval errors (relative to semantic) increase, bias toward correct repetition of high-imageability words increases. Conclusions Results suggest that word retrieval and verbal STM tasks likely rely on a partially shared temporary linguistic activation process.

Language treatment prior to anterior temporal lobe surgery: Can naming skills be preserved?

Epilepsy affects 1% of the general population and is highly prevalent among Veterans. The purpose of this phase I study was to investigate a presurgical linguistically distributed language treatment program that could potentially diminish effects of proper-name retrieval deficits following left anterior temporal lobe resection for intractable epilepsy. A single-subject multiple-baseline design was employed for three individuals with late-onset chronic left temporal lobe epilepsy. Word retrieval treatment was administered prior to anterior temporal lobe resection. The primary outcome measure was confrontation naming of proper nouns. Immediately posttreatment (before surgery), there was a positive effect for all trained stimuli in the form of improved naming as compared with pretreatment. In addition, trained stimuli were found to be better after surgery than they were at pretreatment baseline, which would not be expected had language treatment not been provided. This series of case studies introduces two fundamentally novel concept: that commonly occurring deficits associated with left temporal lobe epilepsy can be treated despite the presence of damaged neural tissue and that providing this treatment prior to surgery can lead to better preservation of language function after surgery than would be expected if the treatment were not provided.