Biomedical subjects

Lyndsey Nickels

Publications and source records attributed to Lyndsey Nickels.

4 recordsLinked to original sources

PubMed2007

Topographical disorientation: towards an integrated framework for assessment.

Topographical disorientation, the inability to find one's way in large-scale environments, is a relatively common disorder. However, there are relatively few cognitive neuropsychological studies that investigate the nature of topographical cognition. Theoretical progress has been hindered by a number of factors including: terminological confusion; lack of theoretically driven assessment; the use of broad classifications for the nature of underlying impairments; and an ongoing failure to examine topographical skills in real-life settings. As a result, there is currently no well-established or widely accepted theoretical framework encompassing all aspects of this multifaceted area of cognition. In addition, there is a relative paucity of published case studies that include a comprehensive, theoretically based assessment of topographical disorientation, and treatment of the disorder has received virtually no formal investigation (with the exception of Davis & Coltheart, 1999). Thus, the current paper focuses on the development of a broad framework for understanding topographical cognition that integrates a number of recent theories of topographical orientation and mental imagery (Farah, 1984; Kosslyn, 1980; Riddoch & Humphreys, 1989). The aim of the paper is to present a preliminary framework that can be used as a basis for further refinement and development of theoretical proposals, and be employed by clinicians as a starting point for assessment planning.

Cognition↗

PubMed2007

Assessment and treatment of childhood topographical disorientation: a case study.

Topographical disorientation refers to individuals who are unable to find their way around large-scale environments in a normal manner. Childhood topographical disorientation is rarely investigated or reported. Treatment of topographical disorientation is also rare with only one reported treatment study in an adult (Davis & Coltheart, 1999) and no known description of treatment in a child. This paper reports a detailed case analysis of CA, a 6-year-old child with topographical disorientation, and a description of a treatment programme focused on training orientation in the school environment. Assessment of CA revealed mild to moderate visual agnosia in conjunction with severe impairments in general spatial learning and memory, topographical new learning and memory, and a total inability to learn new topographical routes. CA was also unable to use a mental image of his environment, a simple visual plan of his environment or a simple visual map, but was able to follow verbally mediated topographical instructions. The treatment programme focused on improving CA's topographical orientation in the school environment. The programme first involved training in recognition of major school buildings and landmarks and then focused on practical training in route finding along commonly used routes in the school environment. Clear benefits from treatment were evident. The assessment and treatment methods employed provide practical and useful ideas for management of this condition in other children.

Child↗

PubMed2006

Cumulative semantic inhibition in picture naming: experimental and computational studies.

We report an experiment in which subjects named 120 pictures, consisting of series of five pictures drawn from each of 24 semantic categories (and intermixed with 45 fillers). The number of intervening trials (lag) between successive presentations of members of the same category varied from two to eight. Subjects' naming latencies were slowed by 30 ms for each preceding member of the category. This effect was both cumulative and linear, and unrelated to the lag elapsing since the previous presentation of a category member. These results definitively demonstrate the occurrence of cumulative interference for word retrieval by prior retrieval of other exemplars of the same semantic category-cumulative semantic inhibition. We claim that this inhibition effect could only occur if the spoken word production system possesses three specific properties (competition, priming, and sharing of semantic activation). We provide computational-modelling evidence in support of this claim. We show that no current theory of spoken word production has all of these properties. In their current form, all these theories are falsified by these results. We briefly discuss the obstacles that may be encountered by current models were they modified to account for our findings.

Adolescent↗

PubMed2006

Treatment of irregular word spelling in acquired dysgraphia: selective benefit from visual mnemonics.

In contrast to the numerous treatment studies of spoken language deficits, there have been relatively few studies concerned with the treatment of spelling disorders. Among these, there have been only a small number that have targeted specific components of the spelling process. We describe a successful single case treatment study for FME, a woman with acquired dysgraphia, which was conducted within a cognitive neuropsychological framework. Pre-treatment assessment revealed a semantic deficit, impaired access to output orthography and probable additional degradation of the actual representations within the orthographic output lexicon. The treatment study was therefore directed towards relearning spellings by strengthening, and facilitating access to, specific orthographic representations for writing. In order to maximise the functional outcome for FME, treatment was focused on high frequency, irregular words. The treatment programme was carried out in two phases, one without and one with the use of mnemonics, and the results showed a selective training effect with the mnemonics alone. Treatment benefits were item specific but long lasting, and a significant improvement in FME's spelling performance was still evident at 2 months post-treatment. The current study confirms how cognitive neuropsychological theories and methods can be successfully applied to the assessment of acquired spelling impairments, and exemplifies how treatment with carefully designed mnemonics is of benefit if the inability to retrieve orthographic representations for writing is aggravated by a semantic deficit.

Agraphia↗