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
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
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
NEURONAL RESPONSES ELICITED BY VIEWING HUMAN BODY MOTION AND GESTURE.
Funder
National Health and Medical Research Council
Funding Amount
$135,822.00
Summary
This project aims to study human brain regions active in viewing movements of the body, face and hands, as well as gestures (i.e. movements with meaning). We will map the location of these human motion sensitive brain regions relative to brain areas dealing with other visual functions. We will use a new method of brain scanning (functional MRI) and recordings of the electrical activity of the brain to achieve these goals. Subjects for this project will be epilepsy patients undergoing investigati ....This project aims to study human brain regions active in viewing movements of the body, face and hands, as well as gestures (i.e. movements with meaning). We will map the location of these human motion sensitive brain regions relative to brain areas dealing with other visual functions. We will use a new method of brain scanning (functional MRI) and recordings of the electrical activity of the brain to achieve these goals. Subjects for this project will be epilepsy patients undergoing investigation for seizure surgery at the A and RMC and Royal Children's Hospitals in Melbourne. Functional MRI - a new non-invasive method for studying brain function - will locate the brain structures involved in the detection and analysis of human motion. Recording electrodes are surgically placed inside the brains of these patients in order to find the source of their seizures, and these electrodes will be utilised for this study. A number of facial, hand and body movement and gestural stimuli will be used. First, brain locations responding to face, hand and body movements will be identified. It is predicted that regions sensitive to hand motion could be located near areas known to participate in adjusting the subject's own visually-guided reaching behaviour. Similarly, regions sensitive to facial motion could be located near areas thought to deal with lip-reading. Second, differences in brain activity to gestures and movements of the face and hand will be studied, so as identify brain regions that process increasingly complex information. Third, differences in brain responses to incompatible (e.g. head facing left and moving right) versus compatible human motion will be studied. A brain 'map' with locations of these human motion sensitive regions relative to visually sensitive regions will be generated. These data will not only aid planning for future seizure surgery, but have implications for our understanding of the visual aspects of motor apraxia.Read moreRead less
Visuomotor Integration In The Medial Parietal Cortical Areas
Funder
National Health and Medical Research Council
Funding Amount
$665,163.00
Summary
This project will find out how the electrical activity of brain cells is used to direct the arms to a specific position in the space around a person's body. By understanding the code used by brain cells to perform this control of the arms, we will be able to "read" the brain activity directly, and use it to allow control of artificial arms by people who have been paralysed or had amputations.
Understanding The Organisation Of The Medial Parietal Cortex: Sensorimotor Integration For Goal-directed Behaviour
Funder
National Health and Medical Research Council
Funding Amount
$551,862.00
Summary
Reaching and grasping are of obvious significance for a productive life, and many of the brain areas known to be involved in the direction of arm movements are located in the parietal lobe. Stroke affecting this part of the brain causes disability, as people become unable to reach accurately, or to close their hands around objects with appropriate strength. This project will combine modern physiological and anatomical methods to reveal the brain circuitry responsible for such crucial skills.
Mechanisms And Pathways Leading To Saccadic Suppression In Primate Brain
Funder
National Health and Medical Research Council
Funding Amount
$858,086.00
Summary
Only the central few degrees of the visual field are viewed in high resolution. Consequently, the eyes must be pointed at targets of interest using saccadic eye movements. Each saccade generates potentially disturbing image motion but this is never perceived: saccadic suppression. This project aims to characterise the neural basis of saccadic suppression using modern techniques. As a result, a prime question in Neuroscience for over 100 years can now be answered.