Integrative Role Of Feedback Projections To Cat Primary Visual Cortex
Funder
National Health and Medical Research Council
Funding Amount
$293,321.00
Summary
Although in the last decade termed The Decade of the Brain we have learned a lot about the brain, the gaps in our understanding of brain functions are still enormous. The analysis of information in the sensory parts of the brain appears to be arranged in a distributed - hierarchical way. For example, different types of nerve fibres leaving the eye carry fairly generalised information about the external visual world along distinct parallel information channels. By the time the signals reach cereb ....Although in the last decade termed The Decade of the Brain we have learned a lot about the brain, the gaps in our understanding of brain functions are still enormous. The analysis of information in the sensory parts of the brain appears to be arranged in a distributed - hierarchical way. For example, different types of nerve fibres leaving the eye carry fairly generalised information about the external visual world along distinct parallel information channels. By the time the signals reach cerebral cortex there is a dramatic increase in complexity of visual stimuli to which cells respond (orientation, length and direction of movement of contours became important). There are at least two parallel feedforward information processing streams across the cerebral cortex involving a number of relay stations at each of which there are further specializations. For example, cells in one area appear to respond only to faces while in some other areas cells respond to motion in particular directions almost irrespective of the position of the stimuli. In the human there are more than 30 visual cortical areas. What is very surprising that from all these areas there are extensive feedback pathways running back to the lower-order areas. The feedback pathways appear to largely criss-cross different information processing streams and their function is very poorly understood. We will record from cells in lower-order areas noting the way they respond to different stimuli. Then we will block the feedback pathway from a particular higher-order area by cooling the area to about 10oC. We have confirmed that this prevents nerve impulses leaving the cooled area. Then we repeat our tests on the cell in the lower-order area. Comparing the responses with and without feedback activity will tell us what the feedback is doing. Understanding the function of feedback pathways hopefully would help us to understand the mechanisms underlying some subtle psychoneurological diseases.Read moreRead less
The Claustrum Enigma: Unlocking The Role Of The Last Unknown Area Of The Primate Brain
Funder
National Health and Medical Research Council
Funding Amount
$558,364.00
Summary
Despite nearly 200 years of study, the function of the claustrum remains unclear. Interest in this brain structure has recently been revived by findings showing damage to the claustrum in several major diseases, and by the suggestion that the claustrum may have a role in consciousness. Here we propose a series of experiments to test the novel hypothesis that the claustrum is part of the default mode network, a group of brain areas that act together when we aren't thinking about anything in parti ....Despite nearly 200 years of study, the function of the claustrum remains unclear. Interest in this brain structure has recently been revived by findings showing damage to the claustrum in several major diseases, and by the suggestion that the claustrum may have a role in consciousness. Here we propose a series of experiments to test the novel hypothesis that the claustrum is part of the default mode network, a group of brain areas that act together when we aren't thinking about anything in particular, that is- most of the time.Read moreRead less
Plasticity In The Thalamic Reticular Nucleus During Normal And Altered Postnatal Development
Funder
National Health and Medical Research Council
Funding Amount
$392,036.00
Summary
Thalamic centres concerned with vision send information through the thalamic reticular nucleus to multiple cortical areas in which different aspects of the visual world are analysed. These cortical areas in turn send connections back through the reticular nucleus to the thalamus. Cortical function ultimately depends on the correct connections being established between the sensory receptors and the thalamus and between the thalamus and cortex. Far from being merely a relay station of peripheral s ....Thalamic centres concerned with vision send information through the thalamic reticular nucleus to multiple cortical areas in which different aspects of the visual world are analysed. These cortical areas in turn send connections back through the reticular nucleus to the thalamus. Cortical function ultimately depends on the correct connections being established between the sensory receptors and the thalamus and between the thalamus and cortex. Far from being merely a relay station of peripheral sensory information the dorsal thalamus modifies and interacts with the flow of information around the brain. The reticular nucleus forms an integral part of this information flow. How these connections develop and are modified by disturbance to the visual pathway is crucial to our understanding of brain function. To this end, we will study the connections between three areas of the brain concerned with vision, the thalamic reticular nucleus, the thalamus and the visual cortices. We will focus our study on the development of the reticular nucleus and the importance of a normal visual environment in establishing the proper connections between different brain areas. The importance of studying normal and abnormal development is that it can provide a description of the kinds of experience leading to specific types of neural abnormalites. This information tells us the degree to which connections are malleable and is of potential clinical importance.Read moreRead less
Interaction Of Thalamic And Cortical Activity In The Primate Visual System
Funder
National Health and Medical Research Council
Funding Amount
$487,580.00
Summary
We recently discovered that a primitive part of the visual pathway shows rhythmic nerve cell activity similar to slow brain waves recorded in sleep, anaesthesia, and epilepsy. We now plan to discover whether these primitive cells help to generate brain waves by measuring the timing of their activity together with brain waves in different visual and non-visual parts of the brain. This project will contribute to understanding the role of brain waves in normal brain function and epilepsy.
Neural Circuits For Residual Vision After Damage To Striate Cortex
Funder
National Health and Medical Research Council
Funding Amount
$662,220.00
Summary
Brain cells have the ability to rearrange their connections to create alternate pathways, which compensate for loss of function following brain damage. To understand why some people become blind after damage to the visual cortex, and some don't, we will determine how neural connections change following lesions in different stages of life. The project will provide important information that may allow future development of treatments for blindness due to stroke or traumatic brain injury.