David P. Wilkins

Role of frontal versus temporal cortex in verbal fluency as revealed by voxel-based lesion symptom mapping

Category and letter fluency tasks have been used to demonstrate psychological and neurological dissociations between semantic and phonological aspects of word retrieval. Some previous neuroimaging and lesion studies have suggested that category fluency (semantic-based word retrieval) is mediated primarily by temporal cortex, while letter fluency (letter-based word retrieval) is mediated primarily by frontal cortex. Other studies have suggested that both letter and category fluency are mediated by frontal cortex. We tested these hypotheses using voxel-based lesion symptom mapping (VLSM) in a group of 48 left-hemisphere stroke patients. VLSM maps revealed that category and letter fluency deficits correlate with lesions in temporal and frontal cortices, respectively. Other regions, including parietal cortex, were significantly implicated in both tasks. Our findings are therefore consistent with the hypothesis that temporal cortex subserves word retrieval constrained by semantics, whereas frontal regions are more critical for strategic word retrieval constrained by phonology.

Semantic typology and spatial conceptualization

This project collected linguistic data for spatial relations across a typologically and genetically varied set of languages. In the linguistic analysis, we focus on the ways in which propositions may be functionally equivalent across the linguistic communities while nonetheless representing semantically quite distinctive frames of reference. Running nonlinguistic experiments on subjects from these language communities, we find that a populations cognitive frame of reference correlates with the linguistic frame of reference within the same referential domain.

Grammars of space: Explorations in cognitive diversity

List of figures List of tables List of contributors Preface 1. The background to the study of the language of space Stephen C. Levinson and David P. Wilkins 2. Towards an Arrernte grammar of space David P. Wilkins 3. Sketch of a Jaminjung grammar of space Eva Schultze-Berndt 4. Prolegomenon to a Warrwa grammar of space William B. McGregor 5. The language of space in Yeli Dnye Stephen C. Levinson 6. Prolegomena to a Kilivila grammar of space Gunter Senft 7. A sketch of the grammar of space in Tzeltal Penelope Brown 8. Spatial reference in Yukatek Maya: a survey Jurgen Bohnemeyer and Christel Stolz 9. Approaching space in Tiriyo grammar Sergio Meira 10. Elements of the grammar of space in Ewe Felix K. Ameka and James Essegbey 11. Spatial language in Tamil Eric Pederson 12. A grammar of space in Japanese Sotaro Kita 13. Some properties of spatial description in Dutch Miriam van Staden, Melissa Bowerman and Mariet Verhelst 14. Patterns in the data: towards a semantic typology of spatial description Stephen C. Levinson and David P. Wilkins Appendices References Author index Language/language family index Subject index.

Is Problem Solving Dependent on Language

There has been a long-standing debate in the fields of philosophy and cognitive science surrounding the relationship of language to cognition, but the exact nature of this relationship is still unclear (Sokolov, 1968/1972). In the current study, we explored the role of language in one aspect of cognition, namely problem solving, by administering the Wisconsin Card Sorting Test (WCST) to stroke patients with varying degrees of language impairment (Experiment 1) and to normal participants under conditions of articulatory suppression (Experiment 2). In Experiment 1, there was a significant correlation between performance on the WCST and language measures such as comprehension and naming. Demonstrating the specificity of this result, we also found a significant relationship between language performance and another test of problem solving, the Ravens Colored Progressive Matrices, but no relationship between language and a test of visuospatial functioning. In Experiment 2, normal participants were significantly impaired on the WCST under conditions of articulatory suppression, relative to a baseline condition. Together, these findings suggest that language plays a role in complex problem solving, possibly through covert language processes.

Clinical and anatomical correlates of apraxia of speech.

In a previous study (Dronkers, 1996), stroke patients identified as having apraxia of speech (AOS), an articulatory disorder, were found to have damage to the left superior precentral gyrus of the insula (SPGI). The present study sought (1) to characterize the performance of patients with AOS on a classic motor speech evaluation, and (2) to examine whether severity of AOS was influenced by the extent of the lesion. Videotaped speech evaluations of stroke patients with and without AOS were reviewed by two speech-language pathologists and independently scored. Results indicated that patients with AOS made the most errors on tasks requiring the coordination of complex, but not simple, articulatory movements. Patients scored lowest on the repetition of multisyllabic words and sentences that required immediate shifting between place and manner of articulation and rapid coordination of the lips, tongue, velum, and larynx. Last, all patients with AOS had lesions in the SPGI, whereas patients without apraxia of speech did not. Additional involvement of neighboring brain areas was associated with more severe forms of both AOS as well as language deficits, such as aphasia.

Interjections as deictics

Abstract The paper examines some of the semantic and pragmatic consequences of a form being both a lexeme (i.e. a simple sign) and a conventional utterance. The approach presented here has far-reaching consequences for the manner in which interjections are identified, analyzed, and subclassified. In particular it it suggested that interjections have all the features attributed to utterances, including the facts that they convey complete propositions and have an illocutionary purpose. Given that interjections are context-bound, it is possible to observe that the referential arguments in the propositions conveyed by interjections are provided by context. As lexemes, interjections have ‘real’ semantic (i.e. propositional/conceptual) content, and within the decomposition of all interjections are basic deictic elements such as ‘I U ’, ‘you A ’, ‘now T ’, ‘here P ’, and ‘this I ’. These ‘primitive’ deictic elements are not tied referentially to any entities until they are placed in context. In this sense both a pragmatic and a semantic approach are required to account for interjections. Interjections are, therefore, shifters (indexicals) by virtue of being built semantically out of basic deictic elements and so should be considered a reasonable topic within the study of deixis. Definitions, using the Natural Semantic Metalanguage approach to lexical decomposition, are proposed for a varied range of interjections from English, Mparntwe Arrernte (Central Australia), American Sign Language, and Italian.

Key principles underlying research and practice in AAC

Six principles of AAC research and practice are offered for consideration and discussion within the AAC community. Principle 1 requires the active participation of individuals with complex communication needs (CCN) in all AAC activities. Principle 2 seeks to ensure that theoretical constructs underlying research and development in AAC are grounded, widely accepted, and clearly defined. Principle 3 underscores the need to use ergonomics in the design and development of AAC technologies and instructional strategies. Principle 4 highlights communication partners and the unique roles they play in AAC. Principle 5 accentuates the need to focus on societal roles, relationships, and opportunities made possible by AAC technologies and services. Finally, principle 6 draws attention to the importance of measuring a broad range of AAC outcomes, especially those most significant to primary AAC stakeholders.

Role of the precentral gyrus of the insula in complex articulation

Previous research has suggested that the left anterior insula, specifically the superior precentral gyrus of the insula (SPGI), is a critical brain region for the coordination of complex articulatory movements. However, previous studies have not determined which articulatory factors are specifically dependent on this brain region. In the current study, 33 left hemisphere stroke patients with varying degrees of speech impairment were asked to perform multiple repetitions of single words that varied along three separate dimensions: number of syllables, degree of articulatory travel (i.e., change between places of articulation for consonants), and presence/absence of an initial consonant cluster. The role of the SPGI in performance across the three conditions was determined using voxel-based lesion symptom mapping (VLSM), a statistical approach to lesion analysis that does not require separating patients based on lesion site or symptom profile. Rather, continuous performance data are entered, along with lesions reconstructed in normalized space. Based on preliminary analyses, there was adequate power to detect differences in the SPGI, which was the focus of our predictions. We found that the SPGI was critical for performance on the articulation task across all three conditions, namely, when words were multi-syllabic, required a high degree of travel, or involved an initial consonant cluster. As a control, we also generated a VLSM map for articulation of words with minimal articulatory complexity (i.e., single-syllable words with no initial cluster and a minimal change in place of articulation). In this case, the SPGI was not implicated. The current results suggest that the left SPGI is a critical area for intra- and inter-syllabic coordination of complex articulatory movements, prior to end-stage execution of speech commands.

Anatomical Correlates of Sentence Comprehension and Verbal Working Memory in Neurodegenerative Disease

This study investigates whether sentence comprehension and nonsyntactic verbal working memory (vWM) are sustained by the same or by different neural systems. Scores in a sentence–picture matching task and in digits backward (DB) were correlated with magnetic resonance imaging voxelwise gray matter volumes using voxel-based morphometry in 58 patients with neurodegenerative diseases. Results showed that overall sentence comprehension scores, regardless of grammatical structure, correlated with gray matter volumes in the left temporoparietal region, whereas DB scores correlated with dorsolateral prefrontal and inferior parietal volumes. Comprehension of multiclausal relative sentences (type 3) significantly correlated with voxels in the dorsal portion of the left inferior and middle frontal gyri. When DB and multiclausal relative sentences were directly compared, they showed overlapping neural substrates in the dorsolateral left frontal region, supporting a single source of vWM for syntactic and nonsyntactic tasks. Within this large area of common involvement, a small portion of pars triangularis showed an independent effect of multiclausal sentences, whereas a region in the middle frontal gyrus showed greater correlation with DB. This study reconciles two opposing views, which hold that sentence comprehension and vWM rely on either the same or different anatomical resources.

Twelve tips for effective international clinical placements

As universities adopt an increasingly international focus, student health professionals are keen to gain clinical experiences in other countries. Such clinical placements provide students with the opportunity to share their knowledge and at the same time acquire new clinical and cultural skills. The experience gained will not only enhance their clinical practice overseas, but will also enhance it in their home country where they are likely to work with people from culturally, linguistically and clinically diverse backgrounds. Careful preparation and adequate supports are critical if students and the host institutions are to gain maximum benefit from cross-cultural clinical placements. The tips below are based on an ongoing collaboration between the Indian Institute of Cerebral Palsy, Kolkata, India and The University of Sydney, as well as recommendations from the burgeoning literature on international clinical placements. The authors are from both the sending and the receiving institutions, and have found that close collaboration between the home and host institutions along with student reflection, evaluation and the opportunity to integrate new knowledge with other clinical experiences are keys to a satisfactory outcome for all concerned.