Monthly Archives: November 2009
A functional role for the ventrolateral prefrontal cortex in non-spatial auditory cognition
Spatial and non-spatial sensory information is hypothesized to be evaluated in parallel pathways. In this study, we tested the spatial and non-spatial sensitivity of auditory neurons in the ventrolateral prefrontal cortex (vPFC), a cortical area in the non-spatial pathway. Activity was tested while non-human primates reported changes in an auditory stimulus’ spatial or non-spatial features. We found that vPFC neurons were reliably modulated during a non-spatial auditory task but were not modulated during a spatial auditory task. The degree of modulation during the non-spatial task correlated positively with the monkeys’ behavioral performance. These results are consistent with the hypotheses that the vPFC is part of a circuit involved in non-spatial auditory processing and that the vPFC plays a functional role in non-spatial auditory cognition.
from the Proceedings of the National Academy of Sciences of the United States of America
MEG demonstrates a supra-additive response to facial and vocal emotion in the right superior temporal sulcus
An influential neural model of face perception suggests that the posterior superior temporal sulcus (STS) is sensitive to those aspects of faces that produce transient visual changes, including facial expression. Other researchers note that recognition of expression involves multiple sensory modalities and suggest that the STS also may respond to crossmodal facial signals that change transiently. Indeed, many studies of audiovisual (AV) speech perception show STS involvement in AV speech integration. Here we examine whether these findings extend to AV emotion. We used magnetoencephalography to measure the neural responses of participants as they viewed and heard emotionally congruent fear and minimally congruent neutral face and voice stimuli. We demonstrate significant supra-additive responses (i.e., where AV > [unimodal auditory + unimodal visual]) in the posterior STS within the first 250 ms for emotionally congruent AV stimuli. These findings show a role for the STS in processing crossmodal emotive signals.
from the Proceedings of the National Academy of Sciences of the United States of America
World Color Survey color naming reveals universal motifs and their within-language diversity
We analyzed the color terms in the World Color Survey (WCS) (www.icsi.berkeley.edu/wcs/), a large color-naming database obtained from informants of mostly unwritten languages spoken in preindustrialized cultures that have had limited contact with modern, industrialized society. The color naming idiolects of 2,367 WCS informants fall into three to six “motifs,” where each motif is a different color-naming system based on a subset of a universal glossary of 11 color terms. These motifs are universal in that they occur worldwide, with some individual variation, in completely unrelated languages. Strikingly, these few motifs are distributed across the WCS informants in such a way that multiple motifs occur in most languages. Thus, the culture a speaker comes from does not completely determine how he or she will use color terms. An analysis of the modern patterns of motif usage in the WCS languages, based on the assumption that they reflect historical patterns of color term evolution, suggests that color lexicons have changed over time in a complex but orderly way. The worldwide distribution of the motifs and the cooccurrence of multiple motifs within languages suggest that universal processes control the naming of colors.
from the Proceedings of the National Academy of Sciences of the United States of America
Patients with dysphagia: experiences of taking medication
Conclusion. It is vital to ensure that each patient has an individualized medication regimen, and for patients with dysphagia the formulation of the medicine is as important as the active ingredients.
from the Journal of Advanced Nursing
A mechanical model of vocalization
Work aimed at fighting voice disorders to be presented at Fluid Dynamics Conference in Minneapolis, Nov. 22-24, 2009
from EurekAlert.org
Negative optic aphasia: How much semantics does a name need? Wolff ‘s re-examination of Voit
Background: A prominent model of semantic processing in modern cognitive psychology proposes that semantic memory originates in everyday life experience with concrete objects such as plants, animals, and tools (Martin & Chao, 2001). When the meaning of a concrete content word is being acquired, the learner is confronted with stimuli of various modalities related to the word’s meaning. This comes to be stored as sensory knowledge about the object. It is further postulated that there is a conceptual domain remote from the mechanisms of perception, which is often referred to as functional knowledge or verbal semantics. There is a large body of neuropsychological literature trying to establish how much sensory and functional semantics is needed to access a name, and whether the relative contribution of these types of knowledge is the same for all categories of objects. Another controversial issue is whether naming requires access to semantic knowledge, or whether object names can be accessed directly from vision without the intervention of semantics, as is generally accepted for written word naming. Some support for this assumption seems to come from cases of so-called non-optic aphasia, a condition in which patients can name from visual presentation only but not from any other modality of presentation such as auditory, verbal, tactile, etc. In optic aphasia, a condition far better established, naming is possible from all modalities except vision.
Aims: The aim of this paper is to draw attention to the first case description of non-optic or negative optic aphasia described by Wolff (1897, 1904).
Methods & Procedures: The case describes the results of a re-examination of Voit, who was seen by several neurologists in the course of a decade in classical aphasiology. The patient demonstrated anomia in oral but not in written naming of objects in view. Wolff’s examination involves extensive testing of semantic processing in several modalities, especially with respect to the status of functional and sensory semantic features
Outcomes & Results: The re-examination of patient Voit by Wolff in 1897 with new procedures revealed a specific impairment in processing sensory knowledge, while functional knowledge of objects was relatively preserved. This led to a naming impairment in all modalities of presentation except the visual one. Using more refined tasks, Wolff also demonstrated receptive impairments, in contrast to previous researchers who had concluded that the impairment was restricted to oral production.
Conclusions: Although Wolff’s (1904) case of negative optic aphasia has been almost completely forgotten (but see Bartels & Wallesch, 1996), it is astonishingly modern in its conceptual approach and in the central questions it addresses on the mechanisms involved in the process of naming and on the structure of the semantic system. As is usual in classical cases, the methodology may appear less stringent than in most contemporary work, but the approach was brilliant.
from Aphasiology
Language planning disturbances in children who clutter or have learning disabilities
The primary objective of this paper is to determine to what extent disturbances in the fluency of language production of children who clutter might be related to, or differ from difficulties in the same underlying processes of language formulation seen in children with learning disabilities. It is hypothesized that an increase in normal dysfluencies and sentence revisions in children who clutter reflect different neurolinguistic process to those of children with learning disabilities. To test this idea, 150 Dutch speaking children, aged 10;6 to 12;11 years, were divided in three groups (cluttering, learning difficulties and controls), and a range of speech and language variables were analysed. Results indicate differences in the underlying processes of language disturbances between children with cluttered speech and those with learning disabilities. Specifically, language production of children with learning disabilities was disturbed by problems at the conceptualizator and formulator stages of Levelt’s language processing model, whilst language planning disturbances in children who clutter were considered to arise due to insufficient time to complete the editing phase of sentence structuring. These findings indicate that children who clutter can be differentiated from children with learning disabilities by both the number of main and secondary story plot elements and by the percentage of correct sentence structures.
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.
from Aphasiology
Unravelling nonverbal cognitive performance in acquired aphasia
Background: Nonverbal cognitive constructs are not well understood in patients with acquired aphasia due to stroke. The relative contribution of aphasia, particularly receptive language impairment, to nonverbal function is rarely quantified in studies, although it is assumed to be substantial.
Aims: The purpose of the present study was first to investigate the factor structure of some of the WAIS-III and WMS-III nonverbal tasks in patients with acquired aphasia due to stroke using confirmatory factor-analytic techniques. Second, we sought to determine the degree to which aphasia severity (both auditory comprehension and oral expression), as measured by the Language Competency Index (LCI) of the Boston Diagnostic Aphasia Examination (Goodglass et al., 2001), would account for variance in nonverbal cognitive task performance.
Methods & Procedures: The present study investigated the factor structure of widely used nonverbal cognitive tasks in 136 patients with aphasia due to single left hemisphere stroke, and sought to determine the degree to which language impairment accounted for nonverbal skill. Outcomes & Results: A single factor model representing nonverbal (perceptual) constructs provided the best model fit to the data. The underlying factor structure of nonverbal constructs in patients with aphasia mirrors the structure observed in healthy adults. Although the correlations between language impairment measures and nonverbal skills were moderate, language competence accounted for a minority (about a quarter) of the variance in nonverbal skills.
Conclusions: We conclude that impairment in nonverbal cognitive ability is not fully explained by language competence in people with aphasia.
from Aphasiology
Increased response variability in autistic brains?
One of the key ideas regarding atypical connectivity in autistic brains is the hypothesis of noisier networks. The systems level version of this hypothesis predicts reduced reliability or increased variability in the evoked responses of individuals with autism. Using magnetoencephalography, we examined the response of individuals with autism spectrum disorder versus matched typically developing persons to passive tactile stimulation of the thumb and index finger of the dominant (right) hand. A number of different analyses failed to show higher variability in the evoked response to the thumb or to the index finger in the autism group as compared with typicals. Our results argue against the hypothesis that the brain networks in autism are noisier than normal.
Clinical Evaluation of the Mini-Mental State Exam with Culturally Deaf Senior Citizens
The Mini-Mental State Exam (MMSE) is commonly used to screen cognitive function in a clinical setting. The measure has been published in over 50 languages; however, the validity and reliability of the MMSE has yet to be assessed with the culturally Deaf elderly population. Participants consisted of 117 Deaf senior citizens, aged 55–89 (M = 69.44, SD = 8.55). Demographic information, including state of residence, age, and history of depression, head injury, and dementia diagnoses, were collected. A standard form of the MMSE was used with modification of test administration and stimuli including translation of English test items into a sign-based form and alteration of two items in order to make them culturally and linguistically appropriate. Significant correlations were observed between overall test score and education level (r = .23, p = .01) as well as test score and age (r = –.33, p < .001). Patterns of responses were analyzed and revealed several items that were problematic and yielded a fewer correct responses. These results indicate that clinicians need to be aware of cultural and linguistic factors associated with the deaf population that may impact test performance and clinical interpretation of test results. On the basis of these data, there is an increased risk of false positives obtained when using this measure. Further research is needed to validate the use of this measure with the culturally Deaf population.
Letting the CAT out of the bag: A review of the Comprehensive Aphasia Test. Commentary on Howard, Swinburn, and Porter, “Putting the CAT out: What the Comprehensive Aphasia Test has to offer”
Background: For many years, aphasia batteries have been widely used to assess language difficulties associated with aphasia. Although many clinicians use aphasia batteries in their clinical evaluation, a gradual shift away from these tests has occurred in the last 10 years. Concerns about whether established aphasia batteries fulfil the purposes of assessment have resulted in the development and use of other measures to investigate the effects of brain injury on language function and communication. Recently, a new aphasia battery was published. The Comprehensive Aphasia Test (CAT; Swinburn, Porter, & Howard, 2005) is a standardised test designed to comprehensively assess processes concerned with the recognition, comprehension, and production of spoken and written language. In addition, it attempts to evaluate how any language-processing difficulties identified by the test impact on the individual’s everyday life and record the person’s own perspective of his or her aphasia.
Aims: This paper attempts to provide a critical review of the most widely used aphasia batteries in the UK. It also aims to evaluate the CAT, a relatively new aphasia battery.
Main Contributions: The paper begins with a brief history of aphasia assessment followed by a discussion of the purposes of assessment. Then, some of the aphasia test batteries commonly used in both clinical and research settings in the UK are reviewed. Finally the CAT, the newest aphasia battery for a number of years, is critiqued. Questions are asked about the adequacy of aphasia batteries in general and the CAT in particular to achieve the goals of assessment.
Conclusion: The CAT is a valid and reliable test of language-processing abilities in adults with aphasia. The test identifies the nature of the person with aphasia’s impairments and his or her intact processes. It also provides some insight into how the person feels about his or her aphasia. The information gained may be used to identify further areas for assessment or provide the basis for devising a therapy programme. Given the time constraints experienced in clinical and research settings and the useful information on language skills provided by the CAT, this assessment tool should be of interest to clinicians and researchers.
from Aphasiology
Putting the CAT out: What the Comprehensive Aphasia Test has to offer
Background: The Comprehensive Aphasia Test (CAT; Swinburn, Porter, & Howard, 2005) was published in 2005, the first new aphasia battery in English for 20 years.
Aims: We aim to describe the motivations driving design decisions in the development of the CAT, summarise data on its properties (reliability and validity), and consider reasons why it might be a suitable assessment for clinical use.
Main Contribution: The test is designed to (1) screen for associated cognitive deficits, (2) assess language impairment in people with aphasia, (3) investigate the consequences of the aphasia on the individual’s lifestyle and emotional well-being, and (4) monitor changes in the aphasia and its consequences over time. This lead article discusses the CAT’s advantages over other aphasia batteries available.
Conclusions: We argue that the CAT is based on the best available current theoretical knowledge about the variables known to affect aphasia performance, and gives as much information as is possible from a relatively short standardised aphasia battery for designing therapy plans, while also giving therapists information to make a prognosis when people with aphasia are assessed in the first few months after onset.
from Aphasiology
Spoken word processing and the effect of phonemic mismatch in aphasia
Background: There is evidence that, unlike in typical populations, initial lexical activation upon hearing spoken words in aphasic patients is not a direct reflection of the goodness of fit between the presented stimulus and the intended target. Earlier studies have mainly used short monosyllabic target words. Short words are relatively difficult to recognise because they are not highly redundant: changing one phoneme will often result in a (similar-sounding) different word.
Aims: The present study aimed to investigate sensitivity of the lexical recognition system in aphasia. The focus was on longer words that contain more redundancy, to investigate whether aphasic adults might be impaired in deactivation of strongly activated lexical candidates. This was done by studying lexical activation upon presentation of spoken polysyllabic pseudowords (such as procodile) to see to what extent mismatching phonemic information leads to deactivation in the face of overwhelming support for one specific lexical candidate.
Methods & Procedures: Speeded auditory lexical decision was used to investigate response time and accuracy to pseudowords with a word-initial or word-final phonemic mismatch in 21 aphasic patients and in an age-matched control group.
Outcomes & Results: Results of an auditory lexical decision task showed that aphasic participants were less sensitive to phonemic mismatch if there was strong evidence for one particular lexical candidate, compared to the control group. Classifications of patients as Broca’s vs Wernicke’s or as fluent vs non-fluent did not reveal differences in sensitivity to mismatch between aphasia types. There was no reliable relationship between measures of auditory verbal short-term memory and lexical decision performance.
Conclusions: It is argued that the aphasic results can best be viewed as lexical “overactivation” and that a verbal short-term memory account is less appropriate.
* Esther Janse is now also at the Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands. This study was part of a larger collaborative research programme Auditory processing in speakers with acquired or developmental language disorders. The Dutch Organisation for Scientific Research (NWO) is gratefully acknowledged for funding this research project.
from Aphasiology
