Melbourne School of Psychological Sciences - Theses
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ItemDisturbances in processing inferences in language following right hemisphere brain damage( 1982)It was argued, that contrary to conventional localisation models attributing all linguistic function to the left hemisphere, the right hemisphere played an important part in the processing of paralinguistic information. Studies of disturbances in prosody; understanding of emotional content in verbal messages; processing of visuospatial aspects of language and processing of pictorial information following right hemisphere damage were reviewed. It was suggested that right hemisphere damaged patients appear to have particular difficulty in drawing inferences from verbal messages, implying an inability to integrate verbal information. It was decided to explore the ability of right hemisphere patients to draw simple inferences from material which was deliberately lacking in emotional content and was designed to contrast the ability to process visuospatial information from non-spatial information. A short memory task was created in which recognition of items which were not heard before but which were semantically continuous with the original story would indicate the integration and storing of the information in the story, rather than its actual lexical representation. A pictorial analogue was also designed to explore pictorial processing. A task matching pictorial alternatives to spoken metaphors was also included since it was suggested the right hemisphere patients were unable to do this task. Three experimental groups were explored; right anterior cortical brain damaged patients; right posterior cortical brain damaged patients, and right subcortical (capsular) and sex was also included. The results indicated that contrary to expectation, the right cortical brain damaged group could process inferences in language both spatial and non-spatial. However, it was found that these patients have a particular problem in rejecting recognition items which did not belong to the original set. This difficulty appeared to be exacerbated when the original material was semantically redundent or involved an understanding of spatial relationships. It was speculated that this may reflect a retrieval rather than memorising difficulty. The performance of the cortical patients on pictorial tasks was found to be more severely disturbed than verbal, and this was considered to be possibly due to a failure to resolve the alternative meanings of the pictures. The cortical patients were also found to prefer literal pictorial alternatives for metaphors, more often than controls. This was also speculated to be due to some failure to appreciate the appropriate meaning of the spoken metaphor, or a difficulty in processing the pictorial information correctly to select a picture depicting the appropriate interpretation. The subcortical (capsular) group performed distinctly differently from the cortical group. It was argued that while these patients also had difficulty rejecting items as not belonging to a cognitive set, they also appeared to be performing in a manner originally expected of the cortical group, i.e. there was suspicion that they were not storing information for meaning but for other more superficial characteristics. These patients performed uniformly regardless of the mode of presentation, pictorial or verbal. They also showed some tendency to select literal meanings of metaphors more often than controls.
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ItemNeuropsychological recovery after concussion in Australian rules footballers( 1995)The past 20 years have witnessed a significant growth in research into the neuropsychological sequelae of mild head injury acquired in the course of motor vehicle accidents. Little systematic investigation, however, has been devoted to the neuropsychological consequences of head injury acquired on the sports field. The dearth of research in this area has been detrimental to the formation of adequate policy for the management of injured players. This thesis consists of four studies examining the acute and subacute effects of concussion on cognitive function in Australian rules footballers. Current assessment of post-traumatic amnesia on the field of play is informal, varying from situation to situation, and of unknown sensitivity. The first study considered the sensitivity of orientation and recent memory items in the acute assessment of concussion. Items relating to memory for recent events were found to be more sensitive than orientation items. These findings have important implications for the diagnosis of concussion in sport, particularly in cases where loss of consciousness does not occur or is not observed. Studies two and three examined neuropsychological function in the immediate recovery phase after the resolution of post-traumatic amnesia. While performance on tests of attention and speed of information processing was found to be reduced during the first days after injury, performance returned to normal levels over the first 18 days post-injury. The forth study examined the impact of concussion on sporting competence. There have been concerns that ongoing neurobehavioural effects of concussion might reduce a player’s level of function in competition thereby increasing the risk of suffering further injury. This risk is further compounded by the high attentional demands of the sport. The results showed that players were able to perform at pre-injury levels within 2 to 3 weeks of injury, and that the risk of repeated concussion appeared to be a function of game exposure. Concussed players made a good recovery in terms of neuropsychological measures employed and functional indices of playing performance, reinforcing the view that concussive injury can be associated with reversible neuropsychological consequences. This work contributes to a greater understanding of the neurocognitive sequelae of concussive injury involving low levels of brain commotion and post-injury assessment and recovery of athletes. Further, the present findings have important practical and financial implications for the rehabilitation and management of individuals suffering such injury.