Cortical Neuroprosthesis To Restore Visual Perception To Bling Patients.
Funder
National Health and Medical Research Council
Funding Amount
$189,250.00
Summary
We will develop a medical device to restore visual perception to profoundly blind patients. This device will act to electrically stimulate the visual area of the brain. Electrical stimulation of this area leads to the visual perception of small spots of light in patients who are otherwise blind. By correlating the stimulation of the brain, which leads to the perception of spots of light, with an image of the surrounding environment acquired by a camera and digitally enhanced, we aim to provide b ....We will develop a medical device to restore visual perception to profoundly blind patients. This device will act to electrically stimulate the visual area of the brain. Electrical stimulation of this area leads to the visual perception of small spots of light in patients who are otherwise blind. By correlating the stimulation of the brain, which leads to the perception of spots of light, with an image of the surrounding environment acquired by a camera and digitally enhanced, we aim to provide blind patients with a very basic visual perception of their surroundings.Read moreRead less
Role Of Cortico-cortical Connections In Mediating Cerebral Cortex Plasticity: Visual Cortex Model
Funder
National Health and Medical Research Council
Funding Amount
$362,500.00
Summary
In mammals injury to the retina not only affects the neurones within the eye but also induces changes in the other parts of the brain, particularly in the visual cortex. It has been found that after retinal injury cells in the visual cortex, normally receiving an input from the injured part of the retina, now receive an input from adjacent normal retina ( ectopic receptive field ). All mammals with well developed vision have a large number of separate visual cortical areas (more than 30 in prima ....In mammals injury to the retina not only affects the neurones within the eye but also induces changes in the other parts of the brain, particularly in the visual cortex. It has been found that after retinal injury cells in the visual cortex, normally receiving an input from the injured part of the retina, now receive an input from adjacent normal retina ( ectopic receptive field ). All mammals with well developed vision have a large number of separate visual cortical areas (more than 30 in primates). These areas are arranged in a hierarchy in which it is thought that as features of the visual stimuli become more complex they are discriminated in the areas higher in the hierarchy. These higher-order areas also project back to lower-order areas. This feedback activity from the higher areas can be reversibly abolished by cooling a given area to about 10oC and then rewarming it back to its normal temperature. We will try to determine if in cats (animals with well developed vision) following damage to a small region of the retina the feedback activity from higher visual cortical areas affects the ectopic receptive fields in the lower visual cortical areas. Another possibility is that the ectopic receptive field apparent following retinal damage might depend on horizontal connections within the particular cortical area, running from normal cortex to the area of cortex affected by the lesion. We propose to test this idea by blocking reversibly (with chemical agents) transmission of these horizontal fibres and determining the characteristics of neurones in the area affected by the lesion. Understanding the role of feedback and horizontal cortico-cortical connections in establishing new ectopic receptive fields following spatially delineated damage to the retina will help us to understand the mechanisms underlying perceptual distortions and visual hallucinations which occur following retinal traumas or some age-related retinal degenerations.Read moreRead less
Neuronal Basis Of Stimulus Dependent Receptive Field Properties And The Role Of Feedback Projections
Funder
National Health and Medical Research Council
Funding Amount
$258,000.00
Summary
In mammals with a number of distinct visual cortical areas the processing of information in the visual cortex largely follows a hierarchical order. It has been widely assumed that the neurones at the highest processing level in the visual system are capable of extracting behaviorally significant features from the external visual world by virtue of their large receptive fields. However, there are massive and dense inter-connections between the cortical areas and intra-connections between the neur ....In mammals with a number of distinct visual cortical areas the processing of information in the visual cortex largely follows a hierarchical order. It has been widely assumed that the neurones at the highest processing level in the visual system are capable of extracting behaviorally significant features from the external visual world by virtue of their large receptive fields. However, there are massive and dense inter-connections between the cortical areas and intra-connections between the neurones within the same cortical area. For example the information at the higher processing levels may flow back to the lower ones via the feedback connections. Thus, it is conceivable that the neurones in the primary visual cortex (at the first stage of cortical processing) may posses the properties allowing them to integrate a considerable amount of information from a large area in visual space due to the existence of a dense web of connections. We wish to study the neuronal basis of perceptually related properties in primary visual cortex by examining the detailed receptive field properties of individual neurons and their response characteristics when more complicated visual stimuli are presented in visual space. We will also examine the influence of the feedback connections on the properties of these neurones by silencing the higher-order visual cortical areas which inversely connect to primary visual cortex. It is hoped that by relating our understanding of the basic neuronal properties to their functional roles in visual processing we will obtain further insights concerning the contributions of individual visual cortical areas (primary visual cortex in this project) to the function of visual perception.Read moreRead less
Mechanisms Controlling The Excitability Of Corneal Nociceptor Nerve Terminals
Funder
National Health and Medical Research Council
Funding Amount
$364,759.00
Summary
The project uses a new approach that allows, for the first time, electrical activity to be recorded and analysed from the very fine nerve endings of nerves whose activation results in painful sensations. Using this technique the mechanisms by which substances released in damaged and inflamed tissues lead to discharge of action potentials and the sensation of pain will be investigated. In particular the project investigates the role of a population of sodium ion selective pores (channels) that ar ....The project uses a new approach that allows, for the first time, electrical activity to be recorded and analysed from the very fine nerve endings of nerves whose activation results in painful sensations. Using this technique the mechanisms by which substances released in damaged and inflamed tissues lead to discharge of action potentials and the sensation of pain will be investigated. In particular the project investigates the role of a population of sodium ion selective pores (channels) that are uniquely expressed in pain sensing nerves. These channels have been hypothesised to play an important role in determining the behaviour of these nerves. In addition, the project investigates how some substances released in inflamed tissues sensitize pain sensing nerves, causing them to more readily discharge action potentials. This change is the major cause of pain associated with inflammatory diseases such as arthritis. In summary, the proposed project will provide new insight into how pain sensing nerves function. This knowledge is essential for the development of more effective strategies for treating pain resulting from inflamed and damaged tissue.Read moreRead less
Lesions of the primary visual area (V1) are sufficient to cause blindness, even though there are many other brain areas normally involved in vision. However, when V1 is lesioned very early in life people show some recovery, and may be able to see well enough to perform everyday activities. In order to understand what happens in the brain that allows this preservation of vision, we will study changes in the pathways linking the eyes to the brain, following lesions at different ages.
Combining input from vision and hearing greatly enhances perception when information from one of these senses is degraded or incomplete, such as when tracking objects in foggy, dark or noisy places. This enhancement is of considerable importance because degraded input is the daily situation faced by many people with hearing or vision impairment. We will study the neural processes underlying our ability to combine vision and hearing to create a more reliable and accurate perception of the world.
One of the main trends in the evolution of the primate brain was the huge expansion of the cortical areas devoted to visual processing. However, the exact role of individual areas remains highly controversial, making detailed physiological and anatomical studies in suitable primate models a key step to elucidating their function in the human brain. We will address one particular aspect of this problem, namely the organisation of the cortical areas that provide visual control for skilled movement ....One of the main trends in the evolution of the primate brain was the huge expansion of the cortical areas devoted to visual processing. However, the exact role of individual areas remains highly controversial, making detailed physiological and anatomical studies in suitable primate models a key step to elucidating their function in the human brain. We will address one particular aspect of this problem, namely the organisation of the cortical areas that provide visual control for skilled movements. It is proposed that there are two parallel brain circuits involved in the analysis of motion, one tracking the movement of objects, and the other analysing a person s self-motion. Consider, for example, the task of a tennis player who has to return a serve. In order to achieve this, the brain must precisely integrate information about the ball s motion, as well as information about the player s speed and direction. This requires precise control of eye movements (to keep the eyes on the ball), as well as the ability to control the limb and trunk muscles. The aim of this study will be to map the anatomical framework underlying our ability to process all the relevant visual motion information, and to coordinate the appropriate motor responses. Such work is fundamental for understanding the functional organisation of the brain. It also has the potential to lay the groundwork for developments in areas of applied research, including medicine (e.g. the design of better rehabilitation strategies for people with brain damage), robotics- artificial intelligence (e.g. the improvement of artificial systems capable of vision), and the cognitive sciences (e.g. a better understanding of factors that limit human responses to visual stimuli).Read moreRead less
Over thirty different areas, comprising nearly half the primate cerebral cortex, are involved in processing visual information. From the anatomical viewpoint, each of these areas should be capable of receiving visual information independently, through parallel anatomical channels involving the brainstem. Yet, it has been observed that lesion of one particular area (the primary visual area, V1) results in loss of vision. This raises several questions. What type of visual information is carried by ....Over thirty different areas, comprising nearly half the primate cerebral cortex, are involved in processing visual information. From the anatomical viewpoint, each of these areas should be capable of receiving visual information independently, through parallel anatomical channels involving the brainstem. Yet, it has been observed that lesion of one particular area (the primary visual area, V1) results in loss of vision. This raises several questions. What type of visual information is carried by the parallel pathways to the other visual areas? Why aren t these other areas capable of sustaining vision without V1? Do V1 lesions trigger changes in the adult brain, which affect the other visual areas? As a step towards answering these questions, we will study the neural pathways that convey visual information directly to the middle temporal area (MT). MT is one of the best-characterised visual areas, and the anatomy of its neural inputs is well known, facilitating the interpretation of the results. We will investigate the type of visual information being sent to MT after lesions of V1, as well as the changes in the electrical responses of MT cells which result from this type of condition. This is a basic science study, the primary benefit of which will be advancement of knowledge on the mechanisms that underlie visual processing in normal and pathological situations. However, this type of work may also lay the groundwork for developments in areas of applied research. These may include medicine (e.g. the design of better rehabilitation strategies for people with brain damage), robotics- artificial intelligence (e.g. the development of more robust artificial systems capable of vision), and cognitive sciences (e.g. a better understanding of factors that limit human responses to visual stimuli).Read moreRead less
The Neural Control Of Serotonin Release From Intestinal Enterochromaffin (EC) Cells
Funder
National Health and Medical Research Council
Funding Amount
$117,187.00
Summary
Many functional gastrointestinal problems are believed to be caused by a disruption of the normal functioning of the nerves within the wall of the gut. These nerves are believed to receive information about the contents of the intestine from a specialised class of cell lining the inside wall of the gut called the enterochromaffin cell. The enterochromaffin cell does this job by modulating the release of the transmitter serotonin. In some disorders, like the Irritable Bowel Syndrome (IBS) which c ....Many functional gastrointestinal problems are believed to be caused by a disruption of the normal functioning of the nerves within the wall of the gut. These nerves are believed to receive information about the contents of the intestine from a specialised class of cell lining the inside wall of the gut called the enterochromaffin cell. The enterochromaffin cell does this job by modulating the release of the transmitter serotonin. In some disorders, like the Irritable Bowel Syndrome (IBS) which can affect the upper and lower intestine, the information that serotonin carries can become confused. Thus, the control of the release of serotonin from the enteroendocrine cell is an important process to understand in health and in disease. We will investigate this release directly in isolated tissues from guinea pig small and large intestine and from human large intestine. This study will examine the role of serotonin and the modulation of its release from the enterochromaffin cell. Problems with serotonin release may underlie disease, thus, understanding how this release is controlled will provide a foundation for new and specific therapies that target channels or receptors specific to the release of serotonin. These data could help to develop therapies for gastrointestinal problems such as the IBS, chronic intestinal pseudo-obstruction and gastro-oesophageal reflux disease. The release of serotonin is also intimately linked with the diarrhea associated with cholera and anti-cancer treatments. The proposed study will contribute to the ongoing development of specific therapies that block serotonin receptors on the nerve terminal and will lead to new therapies that compliment existing therapies by modulating the release of serotonin.Read moreRead less
Cortical Interactions Between Afferent Channels In Macaque Visual System
Funder
National Health and Medical Research Council
Funding Amount
$380,154.00
Summary
There are three distinct groups of cells that carry the visual information from the eyes to the brain, each pathway signaling a different aspect of the visual scene. This project will study in detail the lesser known of these three pathways (koniocellular neurones): what sort of information they carry into the brain, how it is combined with the other pathways to yield our composite picture and where in the brain such combination takes place.