Human brain regions required for the dividing and switching of attention between two features of a single object

This combined PET and ERP study was designed to identify the brain regions activated in switching and divided attention between different features of a single object using matched sensory stimuli and motor response. The ERP data have previously been reported in this journal [64]. We now present the corresponding PET data. We identified partially overlapping neural networks with paradigms requiring the switching or dividing of attention between the elements of complex visual stimuli. Regions of activation were found in the prefrontal and temporal cortices and cerebellum. Each task resulted in different prefrontal cortical regions of activation lending support to the functional subspecialisation of the prefrontal and temporal cortices being based on the cognitive operations required rather than the stimuli themselves.

Further evidence for a deficit in switching attention in schizophrenia

In this study, sustained, selective, divided, and switching attention, and reloading of working memory were investigated in schizophrenia by using a newly developed Visual Attention Battery (VAB). Twenty-four outpatients with schizophrenia and 24 control participants were studied using the VAB. Performance on VAB components was correlated with performance of standard tests. Patients with schizophrenia were significantly impaired on VAB tasks that required switching of attention and reloading of working memory but had normal performance on tasks involving sustained attention or attention to multiple stimulus features. Switching attention and reloading of working memory were highly correlated with Trails (B - A) score for patients. The decline in performance on the switching-attention task in patients with schizophrenia met criteria for a differential deficit in switching attention. Future research should examine the neurophysiological basis of the switching deficit and its sensitivity and specificity to schizophrenia.

Eye-movements and visual imagery : a working memory approach to the treatment of post-traumatic stress disorder

It has been claimed that the symptoms of post-traumatic stress disorder (PTSD) can be ameliorated by eye-movement desensitization-reprocessing therapy (EMD-R), a procedure that involves the individual making saccadic eye-movements while imagining the traumatic event. We hypothesized that these eye-movements reduce the vividness of distressing images by disrupting the function of the visuospatial sketchpad (VSSP) of working memory, and that by doing so they reduce the intensity of the emotion associated with the image. This hypothesis was tested by asking non-PTSD participants to form images of neutral and negative pictures under dual task conditions. Their images were less vivid with concurrent eye-movements and with a concurrent spatial tapping task that did not involve eye-movements. In the first three experiments, these secondary tasks did not consistently affect participants' emotional responses to the images. However, Expt 4 used personal recollections as stimuli for the imagery task, and demonstrated a significant reduction in emotional response under the same dual task conditions. These results suggest that, if EMD-R works, it does so by reducing the vividness and emotiveness of traumatic images via the VSSP of working memory. Other visuospatial tasks may also be of therapeutic value.

The manipulation of apoptosis-related genes to generate resistance to Fusarium wilt and water stress in banana

Bananas are susceptible to a diverse range of biotic and abiotic stresses, many of which cause serious production constraints worldwide. One of the most destructive banana diseases is Fusarium wilt caused by the soil-borne fungus, Fusarium oxysporum f. sp. cubense (Foc). No effective control strategy currently exists for this disease which threatens global banana production. Although disease resistance exists in some wild bananas, attempts to introduce resistance into commercially acceptable bananas by conventional breeding have been hampered by low fertility, long generation times and association of poor agronomical traits with resistance genes. With the advent of reliable banana transformation protocols, molecular breeding is now regarded as a viable alternative strategy to generate disease-resistant banana plants. Recently, a novel strategy involving the expression of anti-apoptosis genes in plants was shown to result in resistance against several necrotrophic fungi. Further, the transgenic plants showed increased resistance to a range of abiotic stresses. In this thesis, the use of anti-apoptosis genes to generate transgenic banana plants with resistance to Fusarium wilt was investigated. Since water stress is an important abiotic constraint to banana production, the resistance of the transgenic plants to water stress was also examined. Embryogenic cell suspensions (ECS) of two commercially important banana cultivars, Grand Naine (GN) and Lady Finger (LF), were transformed using Agrobacterium with the anti-apoptosis genes, Bcl-xL, Bcl-xL G138A, Ced-9 and Bcl- 2 3’ UTR. An interesting, and potentially important, outcome was that the use of anti-apoptosis genes resulted in up to a 50-fold increase in Agrobacterium-mediated transformation efficiency of both LF and GN cells over vector controls. Regenerated plants were subjected to a complete molecular characterisation in order to detect the presence of the transgene (PCR), transcript (RT-PCR) and gene product (Western blot) and to determine the gene copy number (Southern blot). A total of 36 independently-transformed GN lines (8 x Bcl-xL, 5 x Bcl-xL G138A, 15 x Ced-9 and 8 x Bcl-2 3’ UTR) and 41 independently-transformed LF lines (8 x Bcl-xL, 7 x BclxL G138A, 13 x Ced-9 and 13 x Bcl-2 3’ UTR) were identified. The 41 transgenic LF lines were multiplied and clones from each line were acclimatised and grown under glasshouse conditions for 8 weeks to allow monitoring for phenotypic abnormalities. Plants derived from 3 x Bcl-xL, 2 x Ced-9 and 5 x Bcl-2 3’ UTR lines displayed a variety of aberrant phenotypes. However, all but one of these abnormalities were off-types commonly observed in tissue-cultured, non-transgenic banana plants and were therefore unlikely to be transgene-related. Prior to determining the resistance of the transgenic plants to Foc race 1, the apoptotic effects of the fungus on both wild-type and Bcl-2 3’ UTR-transgenic LF banana cells were investigated using rapid in vitro root assays. The results from these assays showed that apoptotic-like cell death was elicited in wild-type banana root cells as early as 6 hours post-exposure to fungal spores. In contrast, these effects were attenuated in the root cells of Bcl-2 3’ UTR-transgenic lines that were exposed to fungal spores. Thirty eight of the 41 transgenic LF lines were subsequently assessed for resistance to Foc race 1 in small-plant glasshouse bioassays. To overcome inconsistencies in rating the internal (vascular discolouration) disease symptoms, a MatLab-based computer program was developed to accurately and reliably assess the level of vascular discolouration in banana corms. Of the transgenic LF banana lines challenged with Foc race 1, 2 x Bcl-xL, 3 x Ced-9, 2 x Bcl-2 3’ UTR and 1 x Bcl-xL G138A-transgenic line were found to show significantly less external and internal symptoms than wild-type LF banana plants used as susceptible controls at 12 weeks post-inoculation. Of these lines, Bcl-2 3’ UTR-transgenic line #6 appeared most resistant, displaying very mild symptoms similar to the wild-type Cavendish banana plants that were included as resistant controls. This line remained resistant for up to 23 weeks post-inoculation. Since anti-apoptosis genes have been shown to confer resistance to various abiotic stresses in other crops, the ability of these genes to confer resistance against water stress in banana was also investigated. Clonal plants derived from each of the 38 transgenic LF banana plants were subjected to water stress for a total of 32 days. Several different lines of transgenic plants transformed with either Bcl-xL, Bcl-xL G138A, Ced-9 or Bcl-2 3’ UTR showed a delay in visual water stress symptoms compared with the wild-type control plants. These plants all began producing new growth from the pseudostem following daily rewatering for one month. In an attempt to determine whether the protective effect of anti-apoptosis genes in transgenic banana plants was linked with reactive oxygen species (ROS)-associated programmed cell death (PCD), the effect of the chloroplast-targeting, ROS-inducing herbicide, Paraquat, on wild-type and transgenic LF was investigated. When leaf discs from wild-type LF banana plants were exposed to 10 ìM Paraquat, complete decolourisation occurred after 48 hours which was confirmed to be associated with cell death and ROS production by trypan blue and 3,3-diaminobenzidine (DAB) staining, respectively. When leaf discs from the transgenic lines were exposed to Paraquat, those derived from some lines showed a delay in decolourisation, suggesting only a weak protective effect from the transgenes. Finally, the protective effect of anti-apoptosis genes against juglone, a ROS-inducing phytotoxin produced by the causal agent of black Sigatoka, Mycosphaerella fijiensis, was investigated. When leaf discs from wild-type LF banana plants were exposed to 25 ppm juglone, complete decolourisation occurred after 48 hours which was again confirmed to be associated with cell death and ROS production by trypan blue and DAB staining, respectively. Further, TdT-mediated dUTP nick-end labelling (TUNEL) assays on these discs suggested that the cell death was apoptotic. When leaf discs from the transgenic lines were exposed to juglone, discs from some lines showed a clear delay in decolourisation, suggesting a protective effect. Whether these plants are resistant to black Sigatoka is unknown and will require future glasshouse and field trials. The work presented in this thesis provides the first report of the use of anti-apoptosis genes as a strategy to confer resistance to Fusarium wilt and water stress in a nongraminaceous monocot, banana. Such a strategy may be exploited to generate resistance to necrotrophic pathogens and abiotic stresses in other economically important crop plants.

Effect of orthokeratology on peripheral aberrations of the eye

Purpose: To investigate the effect of orthokeratology on peripheral aberrations in two myopic volunteers. Methods: The subjects wore reverse geometry orthokeratology lenses overnight and were monitored for 2 weeks of wear. They underwent corneal topography, peripheral refraction (out to ±34° along the horizontal visual field) and peripheral aberration measurements across the 42° × 32° central visual field using a modified Hartmann-Shack aberrometer. Results: Spherical equivalent refraction was corrected for the central 25° of the visual fields beyond which it gradually returned to its preorthokeratology values. There were increases in axial coma, spherical aberration, higher order root mean square aberrations, and total root-mean-squared aberrations (excluding defocus). The rates of change of vertical and horizontal coma across the field changed in sign. Total root mean square aberrations showed a quadratic rate of change across the visual field which was greater subsequent to orthokeratology. Conclusion: Although orthokeratology can correct peripheral relative hypermetropia it induces dramatic increases in higher-order aberrations across the field

Interaction between visual status, driver age and distracters on daytime driving performance

This study investigated the effects of visual status, driver age and the presence of secondary distracter tasks on driving performance. Twenty young (M = 26.8 years) and 19 old (M = 70.2 years) participants drove around a closed-road circuit under three visual (normal, simulated cataracts, blur) and three distracter conditions (none, visual, auditory). Simulated visual impairment, increased driver age and the presence of a distracter task detrimentally affected all measures of driving performance except gap judgments and lane keeping. Significant interaction effects were evident between visual status, age and distracters; simulated cataracts had the most negative impact on performance in the presence of visual distracters and a more negative impact for older drivers. The implications of these findings for driving behaviour and acquisition of driving-related information for people with common visual impairments are discussed

Measuring Visual Consistency in 3D Rendering Systems

One of the major challenges facing a present day game development company is the removal of bugs from such complex virtual environments. This work presents an approach for measuring the correctness of synthetic scenes generated by a rendering system of a 3D application, such as a computer game. Our approach builds a database of labelled point clouds representing the spatiotemporal colour distribution for the objects present in a sequence of bug-free frames. This is done by converting the position that the pixels take over time into the 3D equivalent points with associated colours. Once the space of labelled points is built, each new image produced from the same game by any rendering system can be analysed by measuring its visual inconsistency in terms of distance from the database. Objects within the scene can be relocated (manually or by the application engine); yet the algorithm is able to perform the image analysis in terms of the 3D structure and colour distribution of samples on the surface of the object. We applied our framework to the publicly available game RacingGame developed for Microsoft(R) Xna(R). Preliminary results show how this approach can be used to detect a variety of visual artifacts generated by the rendering system in a professional quality game engine.

Patterning fashion : drafting a visual framework

Christine Schmidt uses swimwear to illustrate that the methodological practice of the assemblage of pattern pieces is inherent to the intellectual construction that underpins fashion's cultural and historical discourses. She argues that these common threads are woven together to shape the finished 'global' garment.

Towards a definition of the performing AudioVisualist

The evolution of the laptop computer as a musical instrument in the 1990s provided a tool for empowering the solo musician and divergent approaches to the application of this technology in performance remain consistently debated.  The increasing ubiquity of digital media combined with the power of current generation notebook technology has provided the perfect platform to realise integrated audio-visual toolsets that respond to musical controllers and provide mixed-media results.  Despite emerging practitioners increasingly availing themselves to the musical affordances of this technology, theoretical discussion in the field ignores the various approaches a solo musician might take in developing integrated media works for performance.   In an increasingly crowded niche there is a clear compulsion to consider expanded modes of performance, yet lacking any formal framework these integrations can easily alienate an audience, distract from performance and lead to criticisms of novelty for novelty's sake. 

Seeing pedestrians at night : visual clutter does not mask biological motion

Although placing reflective markers on pedestrians’ major joints can make pedestrians more conspicuous to drivers at night, it has been suggested that this “biological motion” effect may be reduced when visual clutter is present. We tested whether extraneous points of light affected the ability of 12 younger and 12 older drivers to see pedestrians as they drove on a closed road at night. Pedestrians wore black clothing alone or with retroreflective markings in four different configurations. One pedestrian walked in place and was surrounded by clutter on half of the trials. Another was always surrounded by visual clutter but either walked in place or stood still. Clothing configuration, pedestrian motion, and driver age influenced conspicuity but clutter did not. The results confirm that even in the presence of visual clutter pedestrians wearing biological motion configurations are recognized more often and at greater distances than when they wear a reflective vest.

Impact of simulated visual impairment on the cognitive test performance of young adults

Aims: This study investigated the effect of simulated visual impairment on the speed and accuracy of performance on a series of commonly used cognitive tests. ----- Methods: Cognitive performance was assessed for 30 young, visually normal subjects (M=22.0yrs ± 3.1 yrs) using the Digit Symbol Substitution Test (DSST), Trail Making Test (TMT) A and B and the Stroop Colour Word Test under three visual conditions: normal vision and two levels of visually degrading filters (VistechTM) administered in a random order. Distance visual acuity and contrast sensitivity were also assessed for each filter condition. ----- Results: The visual filters, which degraded contrast sensitivity to a greater extent than visual acuity, significantly increased the time to complete (p<0.05), but not the number of errors made, on the DSST and the TMT A and B and affected only some components of the Stroop test.----- Conclusions: Reduced contrast sensitivity had a marked effect on the speed but not the accuracy of performance on commonly used cognitive tests, even in young individuals; the implications of these findings are discussed.

Field instrumentation of a water reticulation pipe buried in reactive soil

The loss of valuable water resources due to pipe failure has become a major problem in Australia, especially in areas under high level of water restrictions. Generally pipe failure occurs due to a combination of physical and environmental factors. Stresses induced by shrinking and swelling of reactive soils are one of the major factors affecting the performance of buried pipes. This paper presents the details of a field instrumentation undertaken to monitor the performance of an in-service water reticulation pipe buried in a reactive soil and subjected to seasonal climatic changes.

Accounts of the visual art classroom : catering for artistically talented students

Inclusive education practices call for the diverse and individual needs of all students to be met satisfactorily. The needs and experiences of artistically talented students in Australian visual art classrooms are currently unknown. This study addresses this gap in research through an inquiry into the experiences of artistically talented students and their teachers in visual art classrooms, by examining the accounts of a group of students and teachers at one high school in South East Queensland. This study is significant as it provides teachers, parents and others involved in the education of artistically talented students with additional means to plan and cater for the educational needs of artistically talented students. Teacher and student accounts of the visual art classroom in this study indicated that identification processes for artistically talented students are unclear and contradictory. Furthermore, teacher and student accounts of their experiences presented a wide variety of conceptions of the visual art classroom and point towards an individualised approach to learning for artistically talented students. This study also discovered a mismatch between assessment practices in the subject visual art and assessment of art in the ‘real world’. Specifically, this study proposes a renewal of programs for artistically talented students, and recommends a revision of current procedures for the identification of artistically talented students in visual art classrooms.

A brush with the real world : the future of inertial motion capture in live performance

3D Motion capture is a medium that plots motion, typically human motion, converting it into a form that can be represented digitally. It is a fast evolving field and recent inertial technology may provide new artistic possibilities for its use in live performance. Although not often used in this context, motion capture has a combination of attributes that can provide unique forms of collaboration with performance arts. The inertial motion capture suit used for this study has orientation sensors placed at strategic points on the body to map body motion. Its portability, real-time performance, ease of use, and its immunity from line-of-sight problems inherent in optical systems suggest it would work well as a live performance technology. Many animation techniques can be used in real-time. This research examines a broad cross-section of these techniques using four practice-led cases to assess the suitability of inertial motion capture to live performance. Although each case explores different visual possibilities, all make use of the performativity of the medium, using either an improvisational format or interactivity among stage, audience and screen that would be difficult to emulate any other way. A real-time environment is not capable of reproducing the depth and sophistication of animation people have come to expect through media. These environments take many hours to render. In time the combination of what can be produced in real-time and the tools available in a 3D environment will no doubt create their own tree of aesthetic directions in live performance. The case study looks at the potential of interactivity that this technology offers.