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.
Functional Anisotropies In The Processing Of Orientation And Direction-of-motion By Human Visual Cortex
Funder
National Health and Medical Research Council
Funding Amount
$366,164.00
Summary
We will study patterns of activity in the human brain to identify the cortical signature of normal visual function. The correspondences between patterns of brain activity and the structure and motion of the visual image in the normal human brain will provide data against which brain activity in a range of disorders from amblyopia to schizophrenia can be assessed.
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.
Neural Basis Of The Functions Of The Primary Visual Cortex: Roles Of Feedforward And Intracortical Inputs
Funder
National Health and Medical Research Council
Funding Amount
$486,280.00
Summary
Signals from the eyes undergo extensive processing at the level of the primary visual cortex so that basic features in the scene such as lines, edges, colours and movement are coded in the activity of individual neurones. This project aims to further our understanding of this process at the basic cellular level. This will not only enable interventions that would help those with poor sight but also give us an insight into basic brain circuitry and its derangement in many neurological disorders.
Integration Of Information By Cells In Mammalian Visual Cortices: Role Of Feedforward And Feedback Inputs.
Funder
National Health and Medical Research Council
Funding Amount
$294,098.00
Summary
In highly 'visual' mammals, such as humans or domestic cats information channels originating in the retina extract and process in parallel information about certain features of the visual world such as shape or motion. The extracted information is sent to the primary visual cortex in the brain. The primary visual cortex 'distributes' this information to different 'higher-order' cortical areas which process the information further. Nerve cells in visual cortices have clearly defined receptive fie ....In highly 'visual' mammals, such as humans or domestic cats information channels originating in the retina extract and process in parallel information about certain features of the visual world such as shape or motion. The extracted information is sent to the primary visual cortex in the brain. The primary visual cortex 'distributes' this information to different 'higher-order' cortical areas which process the information further. Nerve cells in visual cortices have clearly defined receptive fields (RFs), that is, regions of the visual space from which appropriate visual stimuli will activate the cell. Contrary to the previous assumptions however, many of the basic RF properties of cortical neurones are not static but appear to depend on constant dynamic interplay between different components of nerve network in which the neurones are embedded. We wish to study the dynamic changes in the spatial structure of RFs of single neurones in mammalian primary visual cortex. We will examine changes in the structure of RFs of shape processing neurones when low contrast, large visual stimuli are presented. Since the low contrast stimuli extending beyond the confines of RFs of cortical neurones are akin to those in the natural visual scenes we hope to gain insights concerning mechanisms underlying perceptual processing of shapes in natural scenes. We will also study the spatial organization of RFs of neurones in primary visual cortex during reversible inactivation of higher-order visual areas. This will allow us to gain insights concerning the role of 'feedback' projections from the higher-order areas. Furthermore, we will study the responses of cells in one of the higher-order motion processing cortical areas. Comparing the responses in this area to complex motions during normal conditions with those during reversible inactivation of one of the reciprocally connected areas will provide us with insights concerning the mechanisms underlying processing of complex motions.Read moreRead less
Functional Interactions Between Primate Cortical Areas In Tasks Involving Attention And Short-term Memory
Funder
National Health and Medical Research Council
Funding Amount
$267,280.00
Summary
To navigate and operate in the cluttered and dynamic sensory world around us, our brains need to be able to attend to specific objects or features in the environment, identify them and also know where they exist at any one instant of time, prior to performing the appropriate action. The attention, memory, decision and motor components involved in this process possibly involve a variety of cortical areas and neuronal operations. The special primate preparation we have developed permits us to eluc ....To navigate and operate in the cluttered and dynamic sensory world around us, our brains need to be able to attend to specific objects or features in the environment, identify them and also know where they exist at any one instant of time, prior to performing the appropriate action. The attention, memory, decision and motor components involved in this process possibly involve a variety of cortical areas and neuronal operations. The special primate preparation we have developed permits us to elucidate at a neuronal level many of these brain mechanisms. By recording neuronal activities in two different cortical areas simultaneously as the monkey performs a memory task that he has been trained on, we will test the following ideas: (1) A cortical region in the dorsal, parietal stream directs spatial attention by gating other visual areas to process only a selected region of the visual world (2) A region in the ventral, temporal stream directs attention to specific features in the visual world by gating earlier cortical areas (3) The parietal cortical areas that mediate intention for action hold the relevant information in working memory till it is forwarded to the more anterior premotor areas. These experiments have the potential to reveal the basic neuronal scheme that underpins functions such as attention, visual recognition and memory, which are impaired in many neurological disorders.Read moreRead less
Functional Connectivity Between Visual Cortical Areas In The Non-human Primate
Funder
National Health and Medical Research Council
Funding Amount
$387,585.00
Summary
Visual information going from the eyes to the brain is processed in different parts of the brain to extract useful information. However, to be able to select what is important from among the vast number of objects in the scene, top-down signals from higher areas need to act on incoming signals in earlier areas. This project aims to identify what sort of neural pathways are involved in this and how it is done at the cellular level.
Rapid Plasticity In Sensory Systems - Linking Neuronal Adaptation And Perception
Funder
National Health and Medical Research Council
Funding Amount
$650,810.00
Summary
The activity of individual sensory neurons in the brain is surprisingly variable and continuously changing. It is unclear how reliable perception of the world can be generated from the activity of “noisy” neurons, and it remains unclear why neuronal sensitivity should change in the first place! This project will give insights into how groups of sensory neurons collectively overcome their intrinsic variability to support reliable visual perception.
The Pulvinar Is Instrumental In The Development Of Visual Cortical Networks
Funder
National Health and Medical Research Council
Funding Amount
$1,192,911.00
Summary
This Project will elucidate the mechanisms and brain structures involved in visual system development and how their perturbation in early life can lead to neurodevelopmental and cognitive brain disorders, such as Williams and fragile-X syndromes as well as dyslexia. Furthermore, it will demonstrate how the visual brain has a greater capacity to compensate and achieve preservation of vision following an injury in early life.
The superior colliculus is a brain centre which uses visual information from the eyes and other sensory information, such as sound, to direct the head and eyes towards objects of interest. This project will use current advancements in optogenetics to activate connections to this brain region in order to understand its role in coordinating head and eye movements. This will advance our understanding of how the brain collects and processes visual information to subserve behavioural functions.