Anthony J. Angwin

Dopamine and semantic activation: An investigation of masked direct and indirect priming

To investigate the effects of dopamine on the dynamics of semantic activation, 39 healthy volunteers were randomly assigned to ingest either a placebo (n = 24) or a levodopa (n = 16) capsule. Participants then performed a lexical decision task that implemented a masked priming paradigm. Direct and indirect semantic priming was measured across stimulus onset asynchronies (SOAs) of 250, 500 and 1200 ms. The results revealed significant direct and indirect semantic priming effects for the placebo group at SOAs of 250 ms and 500 ms, but no significant direct or indirect priming effects at the 1200 ms SOA. In contrast, the levodopa group showed significant direct and indirect semantic priming effects at the 250 ms SOA, while no significant direct or indirect priming effects were evident at the SOAs of 500 ms or 1200 ms. These results suggest that dopamine has a role in modulating both automatic and attentional aspects of semantic activation according to a specific time course. The implications of these results for current theories of dopaminergic modulation of semantic activation are discussed.

A Functional MRI Study of the Relationship Between Naming Treatment Outcomes and Resting State Functional Connectivity in Post-Stroke Aphasia

The majority of studies investigating the neural mechanisms underlying treatment in people with aphasia have examined task‐based brain activity. However, the use of resting‐state fMRI may provide another method of examining the brain mechanisms responsible for treatment‐induced recovery, and allows for investigation into connectivity within complex functional networks

The speed of lexical activation is altered in Parkinson's disease.

Disturbed comprehension of complex noncanonical sentences in Parkinsons disease (PD) has been linked to dopamine depletion and delayed lexical retrieval. The aim of the present study was to replicate findings of delayed lexical activation in PD patients with noncanonical sentence processing difficulties, and investigate the influence of dopamine depletion on these changes to lexical access. In the first experiment, 20 patients with PD (tested whilst ‘on’ dopaminergic medication) and 23 controls participated in a list priming experiment. In this paradigm, stimuli are presented as a continuous list of words/nonwords, and semantic priming effects were measured across inter-stimulus intervals (ISIs) of 500 ms, 1000 ms and 1500 ms, with data analyzed using multivariate analyses of variance. The results revealed longer delays in lexical activation for PD patients with poor comprehension of noncanonical sentences, suggesting that the speed of lexical access may be compromised in PD, and that this feature may contribute to certain sentencecomprehension difficulties. In the second experiment, 7 patients with PD who participated in the first experiment, performed the same lexical decision task while ‘off’ their dopaminergic medication. Semantic priming effects were measured across ISIs of 500 ms and 1500 ms. Within group comparisons revealed a different pattern of semantic priming for the PD patients when ‘on’ compared to ‘off’ medication, providing further support for a dopaminergic influence on the speed of information processing and lexical activation.

Semantic activation in Parkinson's disease patients on and off levodopa.

Research suggests that dopamine may exert a neuromodulatory influence on automatic spreading activation within semantic networks. In order to investigate the influence of dopamine depletion on semantic activation in Parkinsons disease (PD), nine patients with PD performed a lexical decision task when on and off levodopa medication. Eleven healthy controls matched to the PD patients in terms of sex, age and education also participated in the study. Both directly related word pairs (e.g., tiger - stripe) and indirectly related word pairs (word pairs related via a mediating word, e.g., chalk - black) were used to measure semantic activation across stimulus onset asynchronies (SOAs) of 270msec, 520msec and 1020msec. Analysis of variance statistics revealed that the activation of directly related and indirectly related targets was slower for the PD group relative to the control group. Within group comparisons revealed further changes to semantic activation in PD patients off medication, with no activation of directly or indirectly related target words evident in PD patients off medication. These results further clarify the nature of dopamines neuromodulatory influence on semantic activation, and suggest that the nature of altered semantic activation in PD may depend on the magnitude of dopamine depletion.

Memory and communication support in dementia: research-based strategies for caregivers

BACKGROUND Difficulties with memory and communication are prominent and distressing features of dementia which impact on the person with dementia and contribute to caregiver stress and burden. There is a need to provide caregivers with strategies to support and maximize memory and communication abilities in people with dementia. In this project, a team of clinicians, researchers and educators in neuropsychology, psychogeriatrics, nursing and speech pathology translated research-based knowledge from these fields into a program of practical strategies for everyday use by family and professional caregivers. METHODS From the available research evidence, the project team identified compensatory or facilitative strategies to assist with common areas of difficulty, and structured these under the mnemonics RECAPS (for memory) and MESSAGE (for communication). This information was adapted for presentation in a DVD-based education program in accordance with known characteristics of effective caregiver education. RESULTS The resultant DVD comprises (1) information on the nature and importance of memory and communication in everyday life; (2) explanations of common patterns of difficulty and preserved ability in memory and communication across the stages of dementia; (3) acted vignettes demonstrating the strategies, based on authentic samples of speech in dementia; and (4) scenarios to prompt the viewer to consider the benefits of using the strategies. CONCLUSION Using a knowledge-translation framework, information and strategies can be provided to family and professional caregivers to help them optimize residual memory and communication in people with dementia. Future development of the materials, incorporating consumer feedback, will focus on methods for enabling wider dissemination.

The influence of dopamine on semantic activation in Parkinson's disease : Evidence from a multipriming task

Research has suggested that semantic processing deficits in Parkinsons disease (PD) are related to striatal dopamine deficiency. As an investigation of the influence of dopamine on semantic activation in PD, 7 participants with PD performed a lexical-decision task when on and off levodopa medication. Seven healthy controls matched to the participants with PD in terms of sex, age, and education also participated in the study. By use of a multipriming paradigm, whereby 2 prime words were presented prior to the target word, semantic priming effects were measured across stimulus onset asynchronies (SOAs) of 250 ms and 1,200 ms. The results revealed a similar pattern of priming across SOAs for the control group and the PD participants on medication. In contrast, within-group comparisons revealed that automatic semantic activation was compromised in PD participants when off medication. The implications of these results for the neuromodulatory influence of dopamine on semantic processing in PD are discussed.

Aphasia LIFT: Exploratory investigation of an intensive comprehensive aphasia programme

Background: Intensive comprehensive aphasia programs (ICAPs) are gaining popularity in the international aphasia rehabilitation community. ICAPs comprise at least three hours of treatment per day over at least two weeks, have definable start and end dates for one cohort and use a variety of formats including individual treatment, group therapy, education and technology to improve language and communication. While intensive treatment approaches have demonstrated equivocal results on impairment-based measures, positive changes on activity/participation measures provide support for ICAPs in rehabilitation of chronic aphasia. Aphasia Language Impairment and Functional Therapy (LIFT) is a research-based ICAP developed for the purpose of evaluating treatment outcomes across the International Classification of Functioning, Disability and Health (ICF) domains. Aims: The aim of this study was to estimate the magnitude of treatment effects yielded by Aphasia Aphasia LIFT in the domains of language impairment, functional communication and communication-related quality of life (QOL). Methods & Procedures: Eleven individuals with chronic post-stroke aphasia (mean = 26.9 months) completed Aphasia LIFT. The programme comprised individual impairment-based and functional treatment, group therapy, and computer-based treatment for 40 hours over two weeks (n = 4, LIFT 1) or 100 hours over four weeks (n = 7, LIFT 2). Assessments of confrontation naming, discourse production, functional communication and communication-related quality of life were completed at pre-treatment, immediately post-treatment and six to eight weeks following treatment termination. Outcomes & Results: Group-level analyses revealed acquisition and maintenance of treatment effects, as evidenced by significant improvement on at least one outcome measure at follow-up in all domains. The most consistent pattern of improvement at an individual level was observed on measures of functional communication and communication-related QOL. Conclusions: Aphasia LIFT yielded positive outcomes across ICF domains, and in many cases the treatment effect was enduring. These results demonstrate that Aphasia LIFT was successful in meeting the overarching goal of ICAPs, to maximise communication and enhance life participation in individuals with aphasia. Further research into ICAPs is warranted.

Priming picture naming with a semantic task: An fMRI investigation

Prior semantic processing can enhance subsequent picture naming performance, yet the neurocognitive mechanisms underlying this effect and its longevity are unknown. This functional magnetic resonance imaging study examined whether different neurological mechanisms underlie short-term (within minutes) and long-term (within days) facilitation effects from a semantic task in healthy older adults. Both short- and long-term facilitated items were named significantly faster than unfacilitated items, with short-term items significantly faster than long-term items. Region of interest results identified decreased activity for long-term facilitated items compared to unfacilitated and short-term facilitated items in the mid-portion of the middle temporal gyrus, indicating lexical-semantic priming. Additionally, in the whole brain results, increased activity for short-term facilitated items was identified in regions previously linked to episodic memory and object recognition, including the right lingual gyrus (extending to the precuneus region) and the left inferior occipital gyrus (extending to the left fusiform region). These findings suggest that distinct neurocognitive mechanisms underlie short- and long-term facilitation of picture naming by a semantic task, with long-term effects driven by lexical-semantic priming and short-term effects by episodic memory and visual object recognition mechanisms.

Evaluation of a caregiver education program to support memory and communication in dementia: A controlled pretest–posttest study with nursing home staff

BACKGROUND There is a need for simple multimedia training programs designed to upskill the dementia care workforce. A DVD-based training program entitled RECAPS and MESSAGE has been designed to provide caregivers with strategies to support memory and communication in people with dementia. OBJECTIVES The aims of this study were: (1) to evaluate the effects of the RECAPS and MESSAGE training on knowledge of support strategies, and caregiver satisfaction, in nursing home care staff, and (2) to evaluate staff opinion of the training. DESIGN A multi-centre controlled pretest-posttest trial was conducted between June 2009 and January 2010, with baseline, immediately post-training and 3-month follow-up assessment. SETTING Four nursing homes in Queensland, Australia. PARTICIPANTS All care staff were invited to participate. Of the 68 participants who entered the study, 52 (37 training participants and 15 controls) completed outcome measures at baseline and 3-month follow-up. 63.5% of participants were nursing assistants, 25% were qualified nurses and 11.5% were recreational/activities officers. METHODS The training and control groups were compared on the following outcomes: (1) knowledge of memory and communication support strategies, and (2) caregiver satisfaction. In the training group, the immediate effects of training on knowledge, and the effects of role (nurse, nursing assistant, recreational staff) on both outcome measures, were also examined. Staff opinion of the training was assessed immediately post-training and at 3-month follow-up. RESULTS The training group showed a significant improvement in knowledge of support strategies from baseline to immediately post-training (p=0.001). Comparison of the training and control groups revealed a significant increase in knowledge for the training group (p=0.011), but not for the control group (p=0.33), between baseline and 3-month follow-up. Examination of caregiver satisfaction by care staff role in the training group revealed that only the qualified nurses showed higher levels of caregiver satisfaction at 3-month follow-up (p=0.013). Staff rated the training positively both for usefulness and applicability. CONCLUSION The RECAPS and MESSAGE training improved nursing home care staffs knowledge of support strategies for memory and communication, and gains were maintained at 3-month follow-up. Moreover, the training was well received by staff.

Self-paced reading and sentence comprehension in Parkinson's disease

Parkinsons disease (PD) is associated with disturbances in sentence processing, particularly for noncanonical sentences. The present study aimed to analyse sentence processing in PD patients and healthy control participants, using a word-by-word self-paced reading task and an auditory comprehension task. Both tasks consisted of subject relative (SR) and object relative (OR) sentences, with comprehension accuracy measured for each sentence type. For the self-paced reading task, reading times (RTs) were also recorded for the non-critical and critical processing regions of each sentence. Analysis of RTs using mixed linear model statistics revealed a delayed sensitivity to the critical processing region of OR sentences in the PD group. In addition, only the PD group demonstrated significantly poorer comprehension of OR sentences compared to SR sentences during an auditory comprehension task. These results may be consistent with slower lexical retrieval in PD, and its influence on the processing of noncanonical sentences. (c) 2005 Elsevier Ltd. All rights reserved.