Assessment of semantic processing of words in aphasia: A multi-measurement approach

In this paper we present data from five measures of semantic processing that have been collected from large samples of individuals with diverse aphasia presentations. Measures of central tendency and performance ranges are provided for readers to use in the calculation of standard scores. Our aim in developing this battery is to provide an objective means of determining the extent of semantic impairment. This in turn will help clinicians to differentiate semantically- and phonologically-based word processing impairments and to determine appropriate treatment strategies

Short-form Philadelphia Naming Test: Rationale and Empirical Evaluation

This project translates research findings from the Philadelphia (picture) Naming Test into a clinical tool for diagnosis and measurement of change. The tool is a pair of 5-minute naming tests, each involving a different, representative set of 30 PNT targets. In an evaluation carried out with a well-distributed sample of 25 individuals with chronic aphasia, accuracy scores on the short forms, PNT30-A and –B, were highly correlated with the full PNT and with each other. By utilizing the extensive research database from the PNT, score equivalents and norms are calculated that can be applied in the clinical setting

Power in Voxel-based Lesion–Symptom Mapping

Lesion analysis in brain-injured populations complements what can be learned from functional neuroimaging. Voxelbased approaches to mapping lesion–behavior correlations in brain-injured populations are increasingly popular, and have the potential to leverage image analysis methods drawn from functional magnetic resonance imaging. However, power is a major concern for these studies, and is likely to vary regionally due to the distribution of lesion locations. Here, we outline general considerations for voxel-based methods, characterize the use of a nonparametric permutation test adapted from functional neuroimaging, and present methods for regional power analysis in lesion studies

Informativeness Ratings of Messages Created on an AAC Processing Prosthesis

The SentenceShaperTM is an AAC processing prosthesis that supports spoken language production in aphasia. Prior research comparing narratives produced on and off the system (aided vs. unaided) found that the aided utterances were longer and showed more grammatical structure. Here we show that the “aided effect” also manifests in greater informativeness of messages with functional content. Thirteen unfamiliar listeners used direct magnitude estimation to rate the informativeness of functional narratives produced by five chronic aphasic participants on and off the SentenceShaper. In support of an aided effect, the narratives of four participants were judged more informative in the aided condition

“The Words Get Stuck in My Brain. It Helps Me Get Them Out:” Perspectives on an AAC Aid from Persons with Aphasia

Augmentative and alternative communication (AAC) devices carry risk of avoidance or abandonment by persons with aphasia (PWA). Practice in a controlled setting can offset such risks and establish the context for attitudes assessment as a prelude to real-world deployment. This paper reports on an attitudes assessment carried out with seven PWA following extended practice with SentenceShaper To Go, a high flexibility AAC aid now featuring portability. Aphasia-tailored individual interviews were conducted and analyzed by qualitative methods. Results elucidate attitudes towards this AAC aid and, by extension, others with similar properties

The simulation of action disorganisation in complex activities of daily living

Action selection in everyday goal-directed tasks of moderate complexity is known to be subject to breakdown following extensive frontal brain injury. A model of action selection in such tasks is presented and used to explore three hypotheses concerning the origins of action disorganisation: that it is a consequence of reduced top-down excitation within a hierarchical action schema network coupled with increased bottom-up triggering of schemas from environmental sources, that it is a more general disturbance of schema activation modelled by excessive noise in the schema network, and that it results from a general disturbance of the triggering of schemas by object representations. Results suggest that the action disorganisation syndrome is best accounted for by a general disturbance to schema activation, while altering the balance between top-down and bottom-up activation provides an account of a related disorder - utilisation behaviour. It is further suggested that ideational apraxia (which may result from lesions to left temporoparietal areas and which has similar behavioural consequences to action disorganisation syndrome on tasks of moderate complexity) is a consequence of a generalised disturbance of the triggering of schemas by object representations. Several predictions regarding differences between action disorganisation syndrome and ideational apraxia that follow from this interpretation are detailed

Facilitation of Verb Retrieval Skills in Aphasia: A Comparison of Two Approaches

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Temporal characteristics of semantic perseverations induced by blocked-cyclic picture naming

When unimpaired participants name pictures quickly, they produce many perseverations that bear a semantic relation to the target, especially when the pictures are blocked by category. Evidence suggests that the temporal properties of these "semantic perseverations" may differ from typical lexical perseverations in aphasia. To explore this, we studied semantic perseverations generated by participants with aphasia on a naming task with semantic blocking [Schnur, T. T., Schwartz, M. F., Brecher, A., & Hodgson, C. (2006). Semantic interference during blocked-cyclic naming: Evidence from aphasia. Journal of Memory and Language, 54, 199-227]. The properties of these perseverations were investigated by analyzing how often they occurred at each lag (distance from prior occurrence) and how time (response-stimulus interval) influenced the lag function. Chance data sets were created by reshuffling stimulus-response pairs in a manner that preserved unique features of the blocking design. We found that the semantic blocking manipulation did not eliminate the expected bias for short-lag perseverations (recency bias). However, immediate (lag 1) perseverations were not invariably the most frequent, which hints at a source of inconsistency within and across studies. Importantly, there was not a reliable difference between the lag functions for perseverations generated with a 5 s, compared to 1 s, responsestimulus interval. The combination of recency bias and insensitivity to elapsed time indicates that the perseveratory impetus in a named response does not passively decay with time but rather is diminished by interference from related trials. We offer an incremental learning account of these findings