Auditory Attentional Processes In Stroke Patients With Unilateral Neglect And In Normal Listeners
Funder
National Health and Medical Research Council
Funding Amount
$281,900.00
Summary
A common consequence of a stroke affecting the parietal lobe of the right hemisphere of the brain is a failure to attend to stimuli presented to the left side of the patient. This disorder, called unilateral spatial neglect, affects up to 50% of all stroke sufferers, and poses a significant problem for recovery of function. Neglect has been most widely studied in the modality of vision. Although neglect of auditory stimuli and of stimuli in other modalities has been reported, it has been studied ....A common consequence of a stroke affecting the parietal lobe of the right hemisphere of the brain is a failure to attend to stimuli presented to the left side of the patient. This disorder, called unilateral spatial neglect, affects up to 50% of all stroke sufferers, and poses a significant problem for recovery of function. Neglect has been most widely studied in the modality of vision. Although neglect of auditory stimuli and of stimuli in other modalities has been reported, it has been studied in much less detail, and the relationship between visual and auditory neglect has not been investigated using tasks of similar complexity. One aim of this project is to examine the relationship between auditory and visual neglect using tasks that are carefully matched for complexity and cognitive demands. A second aim relates to the important recent discovery that substantial changes in a visual scene can go unnoticed unless the observer's attention is drawn to them, a phenomenon termed change blindness. The project will examine the ability of normal listeners and of stroke patients to detect changes in complex auditory environments in which sounds arise from multiple sources located in different regions of space. We aim to establish whether there is a change deafness phenomenon analogous to change blindness, and if this is exacerbated in stroke patients with neglect. The results of this project will increase our understanding of the nature of normal auditory attentional processes and of their disruption as a consequence of stroke. The importance of these studies derives from the fact that hearing and attention to auditory stimuli serve a critical role in human communication and as an early warning system for events in the environment that are not within a person's visual field. Increased understanding of disturbances in auditory attention in neglect patients could lead to better rehabilitation of neglect, for which there is currently no effective treatment.Read moreRead less
Neuroanatomical Dynamics Of Attention In Stroke Patients And Healthy Individuals: A Magnetic Stimulation Investigation
Funder
National Health and Medical Research Council
Funding Amount
$360,363.00
Summary
Mechanisms of selective attention are of central importance in guiding human behaviour. The brain uses attention to enhance the processing of information that is behaviourally relevant, and to suppress irrelevant information. The operation of attention within sensory modalities (vision, touch, hearing) has been studied for many decades; however, little is known about how attention combines information between different senses. An understanding of 'crossmodal' attention is important for many reas ....Mechanisms of selective attention are of central importance in guiding human behaviour. The brain uses attention to enhance the processing of information that is behaviourally relevant, and to suppress irrelevant information. The operation of attention within sensory modalities (vision, touch, hearing) has been studied for many decades; however, little is known about how attention combines information between different senses. An understanding of 'crossmodal' attention is important for many reasons. First, real events in the environment provide inputs simultaneously from different locations to multiple senses, and these inputs must be integrated to yield coherent perception. Second, the most basic aspects of human perception depend upon attention; the brain implements selective mechanisms in order to filter the immense quantities of information that constantly bombard our sensory receptors. Finally, many neurological disorders are characterised by impairments of attention; these syndromes are debilitating for the patients themselves, and also place a heavy burden on caregivers and the healthcare system. This project will examine mechanisms of attention in healthy individuals and in stroke patients with attentional deficits. In all experiments, we will employ a new technique in neuroscience called 'transcranial magnetic stimulation' (TMS). TMS enables the safe and reversible stimulation of brain activity in humans. In the current project, we will use TMS with two broad objectives: (i) to determine the key brain areas involved in crossmodal attention in healthy individuals, and (ii) to treat attentional deficits that occur within and between the senses in stroke patients ('magnetic stimulation rehabilitation'). This research will provide important insights into the brain mechanisms that govern selective attention in the healthy brain, and will help guide future methods for managing and treating neurological disorders in which deficits of attention are prominent.Read moreRead less
Eye Movements And The Neural Representation Of Visual Space
Funder
National Health and Medical Research Council
Funding Amount
$459,061.00
Summary
This project will investigate the brain mechanisms that underlie our ability to perceive the locations of objects using vision. This fundamental ability supports a range of important functions including visually-guided reaching, navigation during walking, and spatial awareness, but remains poorly understood. Using physiological, behavioural, and analytical methods, this project will fill a key knowledge gap in visual neuroscience and form a basis for a range of clinical and biomedical advances.
Neurophysiology Of Attention Deficits After Right Hemisphere Stroke
Funder
National Health and Medical Research Council
Funding Amount
$611,742.00
Summary
Stroke is a common and debilitating condition affecting thousands of Australians per year. Problems of attention are common after right hemisphere stroke and arise from lesions to multiple different brain regions. This project utilises a unique multi-modal approach to understand the neurophysiology of sensory, attentional, decision-making and motoric aspects of deficit after right hemisphere stroke and will map these objective signatures to discrete lesion locations.
Investigation Of The Effect Of Prism Therapy On Attention Dysfunction In Right-parietal Lobe Damaged Stroke Patients With Spatial Neglect.
Funder
National Health and Medical Research Council
Funding Amount
$343,888.00
Summary
A strong predictor of a bad outcome after stroke is spatial neglect. This condition is due to a deficit in attention. With attention shifted towards the undamaged side, the victim ignores their damaged side. A new therapy improves neglect, yet little is known about how brain circuits are altered with therapy. We will identify brain areas critical in restoring normal attention, and will investigate for the first time whether repeated therapy sessions improve treatment effectiveness.
Crossmodal Interactions In Selective Attention: A Combined Human Lesion/transcranial Magnetic Stimulation Study
Funder
National Health and Medical Research Council
Funding Amount
$188,182.00
Summary
Aspects of attention are of central importance in guiding human behaviour. The brain uses these mechanisms to enhance the processing of sensory information that is currently relevant for behaviour, and to suppress irrelevant sensory information. Although there is a considerable body of knowledge, from both animal and human research, on how attention operates within individual sensory modalities (vision, touch, hearing, etc.), very little is known about how attention integrates information across ....Aspects of attention are of central importance in guiding human behaviour. The brain uses these mechanisms to enhance the processing of sensory information that is currently relevant for behaviour, and to suppress irrelevant sensory information. Although there is a considerable body of knowledge, from both animal and human research, on how attention operates within individual sensory modalities (vision, touch, hearing, etc.), very little is known about how attention integrates information across these different modalities. An understanding of these 'crossmodal' attentional mechanisms is important for several reasons. First, much brain activity in primary sensory areas is modulated by the attentive state of the individual, so discovering how crossmodal attention works will facilitate our understanding of the neural mechanisms of sensory processing generally. Second, the most basic aspects of human perception are fundamentally dependent upon attention; without attention we would perceive inputs from the different senses as fragmentary, rather than as bound together into coherent multimodal representations. Finally, many acquired and developmental neurological disorders are characterised by debilitating impairments of attention. This project will examine crossmodal spatial attention in stroke patients with damage to an exclusively visual brain area (occipital cortex), or to a multisensory brain area (parietal cortex). It will also measure the extent of crossmodal interactions in healthy participants, using cortical transcranial magnetic stimulation (TMS) to induce reversible, 'virtual' lesions that mimic those of the stroke patients. The specific goals of the research are to explain how inputs from the senses of vision and touch interact to give rise to coherent perception; and to provide an empirical foundation for the development of more effective rehabilitative techniques for stroke patients, by exploiting any preserved crossmodal attentional mechanisms.Read moreRead less
Effects Of Prism Adaptation On Space Perception Following Chronic And Reversible Cortical Lesions
Funder
National Health and Medical Research Council
Funding Amount
$319,336.00
Summary
Damage to one side of the brain following a stroke often produces a debilitating disorder called spatial neglect. Affected patients persistently ignore objects, sounds or touches on the side of space opposite their brain injury. This disorder occurs despite normal sensory function, and reflects damage to the brain's internal representations of one side of space, causing patients to behave as if that side of space no longer exists. Spatial neglect is difficult to rehabilitate and is a major predi ....Damage to one side of the brain following a stroke often produces a debilitating disorder called spatial neglect. Affected patients persistently ignore objects, sounds or touches on the side of space opposite their brain injury. This disorder occurs despite normal sensory function, and reflects damage to the brain's internal representations of one side of space, causing patients to behave as if that side of space no longer exists. Spatial neglect is difficult to rehabilitate and is a major predictor of poor functional recovery after stroke, but there are no effective treatments for it. A promising new treatment for spatial neglect has been recently discovered, which involves patients practicing pointing to a visual target while wearing spectacle-mounted prism lenses that systematically correct for their altered view of the world. Following a brief period of this training, patients' show increased ability to perceive visual objects presented to the previously neglected side of space. Studies have shown that the prism treatment can have long-term benefits for many neglect sufferers. However, it is not known what the brain mechanisms underlying the treatment effects are, and to what degree the effects generalize to all affected senses. The proposed project aims to investigate whether prism treatment ameliorates spatial neglect of sounds as well as visual objects in a group of stroke patients. The project will also systematically examine which part of the brain is critical for the beneficial effects of prism treatment by using focal magnetic stimulation to create reversible, virtual lesions in the brains of healthy participants. Addressing these issues has clear implications for identifying suitable candidates for the treatment, and for understanding how the sensory world is represented in the human brain.Read moreRead less