Auditory-verbal Short-term Memory Research Articles

Speech and Language in Primary Progressive Anarthria

We describe a patient with a progressive loss of speech up to muteness due to frontal atrophy. The clinical and neuropsychological examination documented a severe progressive articulatory disorder associated with a mild language deficit consisting of agrammatic production and spelling errors. Investigation of the patient’s auditory-verbal short-term memory system revealed a selective impairment of the articulatory rehearsal system (covert re-circulation of verbal information), suggesting that not only overt but also covert articulation is impaired in this pathology. The conclusion is drawn that pure anarthria is a disorder of executive aspects of language. The hypothesis is advanced that language deficits such as spelling errors and agrammatic features might be due to ineffective covert articulation.

Phonology: A Review and Proposals from a Connectionist Perspective

A parallel distributed processing (PDP) model of phonological processing is developed, including components to support repetition, auditory processing, comprehension, and language production. From the performance of the PDP reading model of Plaut, McClelland, Seidenberg, and Patterson (1996), it is inferred that the acoustic–articulatory motor pattern associator that supports repetition provides the basis for phonological sequence knowledge. From the observation that many patients make phonemic paraphasic errors in language production, as in repetition, it is argued that there must be a direct link between distributed concept representations (lexical semantic knowledge) and this network representation of sequence knowledge. In this way, both lexical semantic and phonotactic constraints are brought to bear on language production. The literature on phonological function in normal subjects (slip-of-the-tongue corpora) and in patients with aphasia is critically reviewed from this perspective. The relationship between acoustic and articulatory motor representations in the process of phonetic perception is considered. Repetition and reproduction conduction aphasia are reviewed in detail and extended consideration is given to the representation of auditory verbal short-term memory in the model. Finally, the PDP model is reconciled with information processing models of phonological processing, including that of Lichtheim, and with current knowledge of the anatomic localization of phonological processing. Although no simulations of the model were run, a number of simulation studies are proposed.

Identification of the vocabulary learning device in the brain

Vocabulary acquisition is major aspect of language learning in children but also in adults, particularly when learning a foreign language. Selective impairment of vocabulary acquisition is observed in patients with auditory-verbal (phonological) short-term memory deficit, while a more general failure of long-term learning of verbal information is observed in amnesia. Anatomical studies in brain damaged patients have not been fully informative, as they fail to indicate the exact localization of the brain regions involved in vocabulary learning. To identify the relevant brain systems, we performed regional cerebral blood flow (rCBF) PET measurements in six normal subjects while they were learning a list of neologisms or a list of common words.

Phonologically Related Lexical Repetition Disorder: A Case Study

Errors of repetition in aphasia are most often nonword substitutions. Phonologically related lexical errors, or formal errors, are real-word substitutions that overlap with target words in sound. In the present research we present the case of an aphasic patient, MMB, who produced an unusually high rate of formal paraphasias in repetition. Six experiments were conducted to investigate the combination of impairments contributing to MMB's pattern of repetition and to test the predictions made by two theories of formal errors. MMB's formal errors in repetition were influenced by target frequency, but not by target length or imageability. Formal errors tended to be more frequent than their targets and showed greatest phonological overlap with targets at initial consonant. These findings provided partial support for Martin and Saffran's fully interactive spreading activation account of formal errors and did not support Blanken's phonological interactive encoding account. In Experiment 6, the effect on repetition of increasing auditory verbal short-term memory (AVSTM) demands was examined using a paired word repetition experiment. Under these conditions, MMB produced semantic paraphasias for the first time, providing strong support for the Martin–Saffran hypothesis that phonologically related, and semantic, lexical repetition disorders lie on a continuum of severity moderated by the degree of AVSTM impairment.

Deep Dysphasic Performance in Non-fluent Progressive Aphasia: a Case Study

We present a patient (PW) with non-fluent progressive aphasia, characterized by severe word finding difficulties and frequent phonemic paraphasias in spontaneous speech. It has been suggested that such patients have insufficient access to phonological information for output and cannot construct the appropriate sequence of selected phonemes for articulation. Consistent with such a proposal, we found that PW was impaired on a variety of verbal tasks that demand access to phonological representations (reading, repetition, confrontational naming and rhyme judgement); she also demonstrated poor performance on syntactic and grammatical processing tasks. However, examination of PW’s repetition performance also revealed that she made semantic paraphasias and that her performance was influenced by imageability and lexical status. Her auditory-verbal short-term memory was also severely compromised. These features are consistent with ‘deep dysphasia’, a disorder reported in patients suffering from stroke or cerebrovascular accident, and rarely reported in the context of non-fluent progressive aphasia. PW’s pattern of performance is evaluated in terms of current models of both non-fluent progressive aphasia and deep dysphasia.

Deep Dysphasic Performance in Non-fluent Progressive Aphasia: a Case Study

We present a patient (PW) with non-fluent progressive aphasia, characterized by severe word finding difficulties and frequent phonemic paraphasias in spontaneous speech. It has been suggested that such patients have insufficient access to phonological information for output and cannot construct the appropriate sequence of selected phonemes for articulation. Consistent with such a proposal, we found that PW was impaired on a variety of verbal tasks that demand access to phonological representations (reading, repetition, confrontational naming and rhyme judgement); she also demonstrated poor performance on syntactic and grammatical processing tasks. However, examination of PW’s repetition performance also revealed that she made semantic paraphasias and that her performance was influenced by imageability and lexical status. Her auditory-verbal short-term memory was also severely compromised. These features are consistent with ‘deep dysphasia’, a disorder reported in patients suffering from stroke or cerebrovascular accident, and rarely reported in the context of non-fluent progressive aphasia. PW’s pattern of performance is evaluated in terms of current models of both non-fluent progressive aphasia and deep dysphasia.

Relationship between functional and neuropsychological performance in early Alzheimer disease.

Twenty-four subjects with Alzheimer disease underwent cognitive and functional assessment. Functional assessment by caregivers consisted of a 25-item bipolar analog scale measuring activities of daily living and social behaviors divided into four functional domains: memory, attention/executive abilities, everyday skills, and self-care. Cognitive assessment consisted of standardized neuropsychological tests designed to evaluate five cognitive domains: episodic memory, attention/executive function, semantic memory, visuospatial function, and auditory-verbal short-term (working) memory. Functional assessment correlated well with overall severity as measured by Mini Mental State Examination (r = -0.733). Analysis of individual cognitive and functional domains revealed no significant correlation between episodic memory and functional performance. By contrast, functional ability correlated strongly with the cognitive domains of visuospatial function and semantic memory, being significantly greater than the correlation of functional ability with any other cognitive domain. These results were supported by multiple regression analyses that showed visuospatial function to be the sole cognitive predictor of functional abilities. These findings have implications for the evaluation of drug therapies in Alzheimer disease, in particular the effect of current cholinergic therapies on activities of daily living.

The role of speech production in auditory-verbal short-term memory: evidence from progressive fluent aphasia

We report investigations of auditory-verbal short-term memory (AVSTM) in a patient with progressive fluent anomic aphasia. Despite having apparently normal AVSTM as measured by digital span, FM was significantly impaired in immediate serial recall of short sequences of familiar words, and even in reproducing a single word after a filled delay of just a few seconds. In both tasks, unlike normal subjects, she produced numerous phonological errors, often consisting of phonological segments from the intended target word concatenated with segments from other words in the stimulus sequence. Her success in these tasks was modulated (i) consistently by word frequency (high>low), (ii) inconsistently by word imageability (high>low), and (iii) most dramatically by ‘nameability’: that is, FM was much more likely to reproduce a word correctly in AVSTM if it was a word that she could also produce successfully in picture-naming tasks. On the basis of these and additional experiments designed to exclude other interpretations, we conclude that AVSTM may be crucially supported by activation of the lexical phonological representations responsible for production of content words in speech.

Backtracking? Rehearsing and replaying some old arguments about short-term memory

We discuss the role of short-term auditory verbal storage within a working memory system. Data from single case studies of patients with left parietal lesions and selective impairment of memory span are discussed in order to address the question of the functions of short-term memory in language processing. The backup resource of auditory verbal short-term memory is required for those tasks that necessitate backtracking in order to integrate a verbal message within a developing central cognitive representation.

Chronic Auditory Agnosia Following Landau-Kleffner Syndrome: A 23 Year Outcome Study

We report a 27-year-old woman with chronic auditory agnosia following Landau-Kleffner Syndrome (LKS) diagnosed at age 4 1/2 . She grew up in the hearing/speaking community with some exposure to manually coded English and American Sign Language (ASL). Manually coded (signed) English is her preferred mode of communication. Comprehension and production of spoken language remain severely compromised. Disruptions in auditory processing can be observed in tests of pitch and duration, suggesting that her disorder is not specific to language. Linguistic analysis of signed, spoken, and written English indicates her language system is intact but compromised because of impoverished input during the critical period for acquisition of spoken phonology. Specifically, although her sign language phonology is intact, spoken language phonology is markedly impaired. We argue that deprivation of auditory input during a period critical for the development of a phonological grammar and auditory–verbal short-term memory has limited her lexical and syntactic development in specific ways.

Lexical and Semantic Binding Effects in Short-term Memory: Evidence from Semantic Dementia

Two case studies are presented of the short-term memory performance of patients with semantic dementia. The first case showed a pervasive pattern of semantic effects in his auditory verbal short-term memory performance, in particular a marked superiority in serial recall for sequences of ''know n" words over ''unknown" w ords- words w hich he no longer comprehended. His performance in serial recall tasks was characterised by abundant phonemic errors, which occurred w ith a frequency show n to be related to semantic factors. These errors were often migrations of phonemes from one word in the list to another, suggesting that impaired semantic processing reduces the ''glue" or ''binding" that helps to maintain a structured sequence of phonemes in short-term memory. The second patient also showed some semantic effects in serial recall, and a significant but less marked pattern of phonological errors. The differing performance of the two patients is interpreted w ithin an interactive activation model of word production (Saffran & Martin, 1990; Martin, Saffran, & Dell, 1996).

Language and Auditory-verbal Short-term Memory Impairments: Evidence for Common Underlying Processes

We report an investigation of the short-term memory STM impairments of 15 aphasic subjects whose language profiles varied with respect to the relative involvement of lexical-semantic and phonological processes. On the hypothesis that STM is dependent on capacities intrinsic to language processing, repetition span should vary in conjunction with lexical-semantic and phonological impairment: Specifically, when lexical-semantic processing is impaired, phonological abilities provide primary support to span performance; when phonological processing is impaired, there should be increased reliance on lexical-semantic information. Support for this hypothesis was provided by correlating measures of semantic and phonological abilities with effects of imageability and frequency on repetition performance, and with serial position effects in retrieval of phonemes within a word and words within a string. The data are discussed within the framework of an interactive activation model of language processing.

Functional Connectivity in Auditory–Verbal Short-Term Memory in Alzheimer's Disease

Alzheimer's disease (AD) patients show normal patterns of regional cerebral blood flow during performance of subspan verbal memory tasks, but appear to allocate new brain regions when performing supraspan recall tasks. To understand the relationships among these interconnected brain regions, their functional connectivity was considered using principal components analysis (PCA). AD patients and controls were scanned in four conditions: visual fixation only and visual fixation with one-word recall, three-word recall, and eight-word recall. When applied to the data from the three recall task conditions (i.e., eliminating fixation), PCA revealed a significant first component accounting for 75.8% of the variance in the control data and 66.8% of the variance in the patient data. The one-word recall condition had a high positive component score, and the eight-word condition a high negative score. The correlations of individual voxels on this factor (i.e., spatial modes) were very similar between the patients and the controls. The overall similarity in the results of the PCAs between the patients and the controls suggests that they have similar functional connectivity. This would suggest that, at least in the early course of the dementia, the functional CNS organization of verbal memory systems remains normal.

Brain potentials before and during memory scanning

Brain potentials were recorded from 10 normal subjects engaged in a 3-item auditory verbal short-term memory task. A fixed interval (3 s) between the last memory item and the probe was compared to a random interval (1.8–4.2 s with a mean of 3 s). Subjects indicated by button press whether the probe was or was not a member of the memory-set. The same 3-item task was also presented as a counting task and required a button press to the ‘fourth stimulus’ (the probe). The amplitudes of several slow potential shifts preceding and following the probe, and the amplitudes and latencies of the accompanying short duration components (N100, P200) were measured. When the probe appeared at a fixed interval, the amplitude of a slow negative potential in the 300 ms period preceding the probe was slightly larger in the memory than in the counting task. When the probe appeared at a random interval in the memory task, the slow negative shift preceding the probe was absent. Another slow negative shift that peaked at approximately 376 ms after the probe was present in the memory tasks but was absent in the counting task. The amplitude of a late positive shift that peaked at approximately 700 ms after the probe was not different within the memory tasks, or between the memory and counting tasks. N100 amplitude but not P200 amplitude was larger in the memory task when the probe occurred at a fixed than at a random interval. These results suggest that the amplitude of a slow negative shift preceding the probe was related primarily to a temporal expectancy for the appearance of the probe and to a lesser extent to memory processes. In contrast, a slow negative shift that followed the probe occurred only during the memory tasks.

Recovery in Deep Dysphasia: Evidence for a Relation between Auditory–Verbal STM Capacity and Lexical Errors in Repetition

This study investigates the changes in auditory–verbal short-term memory (AVSTM) and error patterns in repetition observed in a Wernicke's aphasic, NC, over a period of about 2 years following the onset of a left middle cerebral artery aneurysm. When first tested, NC demonstrated deep dysphasia, a disorder characterized by the production of semantic errors in repetition and a severe disability in repeating nonwords. At this stage, his AVSTM span, assessed in a pointing task, was less than one item. As NC recovered somewhat, his performance on AVSTM tasks improved (span increased to two items), and his pattern of error in word repetition changed (fewer semantic errors, more formal paraphasias and neologisms). Other features of his span performance after some recovery resembled patterns associated with STM-based repetition impairments (reduced recency effects and reduced word length effects). In a series of computer simulation and empirical studies, we show that NC's repetition performance can be accounted for by varying two parameters of an interactive activation model of repetition adapted from Dell and O'Seaghdha's (1991) model of production: decay rate and temporal interval. These results provide support for the view that AVSTM performance depends on storage capacities intrinsic to the language processing system. Such a model allows deep dysphasia and STM-based repetition disorders to be seen as quantitative variants of the same underlying disturbance.

Phonological and Lexical Coding in Verbal Short-Term-Memory and Learning

A patient with selective auditory phonological coding defect is described. He also showed a defective auditory verbal short-term memory but could learn lists of words flawlessly, thus closely resembling patients with pure short-term memory defects. We argue that the patient′s functional defect could be conceived as a capacity limitation of the phonological short-term store. An experimental evaluation of his verbal short- and long-term memory performances allows a discussion of the interaction of phonological and lexical coding processes in verbal short term memory and learning.

Impaired phonological reading in primary degenerative dementia

SUMMARY This case study reports the profile of preserved and impaired capacities in a left-handed patient suffering from primary degenerative dementia of unknown aetiology. She was remarkable because her relatively preserved object naming and semantic categorization abilities contrasted with severe deficits in speech fluency, oral reading, inability to execute spoken and written commands, and severely impaired auditory-verbal short-term memory. Her reading disorder could be characterized as a disturbance of assembled phonology. She had great difficulty reading pronounceable nonwords, but she could correctly read irregular words. She showed effects of word imageability or concreteness (more than word frequency). She also showed effects of part-of-speech, where nouns and adjectives were read more easily than inflected verbs. She had difficulty reading function words. The syntactic category effects could be proven (by hierarchical log-linear analysis) not to be an artefact of imageability differences between verbs, adjectives and nouns. In reading aloud she made visual and morphological errors, but no semantic errors. This interesting pattern of preserved semantic information and disrupted phonological processing is unusual in dementia and contrasts with the severe dysnomia of patients with surface dyslexia who are able to read by the indirect, assembly-of-phonology route and show better reading of nonwords than irregular words. Her reading by a direct visual-semantic route appeared to be associated with relatively intact object naming, concrete word reading, and irregular word reading, This selective impairment of phonological reading in the context of partly preserved semantic abilities was interpreted as confirmation of the dissociability of language functions in primary degenerative dementia.

Is the Articulatory Loop Articulatory or Auditory? Reexamining the Effects of Concurrent Articulation on Immediate Serial Recall

Results from the paradigm of immediate serial recall form the basis of the influential "articulatory loop" model of auditory-verbal short-term memory (Baddeley, 1986). Central to the development of these ideas have been results obtained in immediate serial recall under the condition of concurrent articulation. We reexamine the affects of concurrent articulation and show that findings from immediate serial recall do not uniquely support the articulatory rehearsal hypothesis: the data can be accounted for by assuming a purely auditory rehearsal process. The question of whether the rehearsal process in fact has an "articulatory" component or is purely "auditory" has significance beyond the immediate domain of working memory, and makes contact with a number of important issues concerning phonological processing. We describe a series of experiments aimed at discriminating between the two hypotheses. Our results support an articulatory component in rehearsal, but also indicate that auditory interference plays a significant, but previously unrecognized, role in the concurrent articulation effect.

Loss of semantic memory: implications for the modularity of mind

Abstract We report a patient, PP, with semantic dementia who was studied longitudinally over two years. During this period she showed a progressive and profound loss of semantic memory affecting factual knowledge, vocabulary, and object knowledge via all sensory modalities. In the face of this near total dissolution of semantic memory, we have addressed the issue of the fate of other cognitive processes. Our findings suggest that nonverbal problem solving, auditory verbal and spatial short-term memory, the high-level visuo-perceptual abilities involved in object constancy, and some basic syntactic processes may operate independently of semantic memory and are therefore independent cognitive modules. In contrast, the integrity of both the phonological representations of words used to produce speech and the representations (or structural descriptions) used to recognise familiar objects appear ultimately to depend on semantic memory.

Functional neuroanatomy of verbal free recall: A replication study

The functional neuroanatomy of verbal memory was investigated using verbal free recall during H2 (15) O positron emission tomography (PET). Twelve young (25-40 years old) normal control subjects participated in eight scans during a single scanning session during which they performed three memory tasks differing by word list length. Four subjects also had scans during a "rest" condition. Temporal lobe activation was observed during all tasks, including single-word repetition. The frontal cortices, specifically Brodmann areas 9 and 10, were activated only when the recall word lists exceeded the memory spans (i. e., 12 and 15 words). Activation was also observed in the anterior cingulate cortex (BA24 and BA32). These data, obtained using a within-subject design, extend previously reported findings that used mixed within-and between-subject designs and demonstrate important functional components of normal auditoryverbal short-term memory. © 1994 Wiley-Liss, Inc.