The Structural Basis Of Direction Selectivity In The Retina
Funder
National Health and Medical Research Council
Funding Amount
$401,705.00
Summary
The retina is part of the central nervous system and there are almost one hundred types of retinal neurons which process visual information before it is passed up the optic nerve to the brain. This project examines how some of these neurons are wired together to form a simple neuronal circuit that detects the direction of a moving object. The elucidation of the cellular mechanisms of direction selectivity will provide an important paradigm of complex processing by simple neuronal circuits, with ....The retina is part of the central nervous system and there are almost one hundred types of retinal neurons which process visual information before it is passed up the optic nerve to the brain. This project examines how some of these neurons are wired together to form a simple neuronal circuit that detects the direction of a moving object. The elucidation of the cellular mechanisms of direction selectivity will provide an important paradigm of complex processing by simple neuronal circuits, with direct relevance to information processing in other parts of the central nervous system. In particular, the project may provide strong evidence for two neuronal strategies that may be of general significance. First, information may be processed at a very local level, which would greatly increase the computational power of a single neuron. Second, neurons may make selective contact with only some processes of an input neuron, which would require novel mechanisms for producing the necessary specificity.Read moreRead less
Distribution Of Neurotransmitter Receptors On Identified Cell Populations In The Primate Retina
Funder
National Health and Medical Research Council
Funding Amount
$421,812.00
Summary
Neurons (nerve cells) communicate with each other by releasing chemicals called neurotransmitters at specialized sites called synapses. Each neuron has synaptic receptors, which determine how it will respond to neurotransmitters released by other neurons. The molecular structure and function of these receptors is well understood. Much less is known about the rules that govern which receptor types are expressed by each type of neuron, and how these receptors are distributed to the appropriate syn ....Neurons (nerve cells) communicate with each other by releasing chemicals called neurotransmitters at specialized sites called synapses. Each neuron has synaptic receptors, which determine how it will respond to neurotransmitters released by other neurons. The molecular structure and function of these receptors is well understood. Much less is known about the rules that govern which receptor types are expressed by each type of neuron, and how these receptors are distributed to the appropriate synapses so as to allow the normal function of the nervous system. We will study the distribution of neurotransmitter receptors on identified neurons in the retina. The retina is part of the central nervous system and its highly ordered structure makes it an ideal model nervous system. We will compare the distribution of receptors on neurons that play distinct functional roles in colour and movement detection. These experiments will advance our understanding of the normal functioning of the nervous system.Read moreRead less
Synaptic Connectivity Of Colour Pathways In Primate Retina
Funder
National Health and Medical Research Council
Funding Amount
$367,500.00
Summary
The first step in the visual process occurs when light enters the eye and activates specialised nerve cells called photoreceptors. The photoreceptors for daytime vision (called cones for their cone-like shape) comprise three types, which are sensitive to the long- (red), medium- (green) or short-wavelength (blue) regions of the visible spectrum. Although the properties of the cones are well known, the way in which they are functionally connected to nerve pathways for vision is not clearly unders ....The first step in the visual process occurs when light enters the eye and activates specialised nerve cells called photoreceptors. The photoreceptors for daytime vision (called cones for their cone-like shape) comprise three types, which are sensitive to the long- (red), medium- (green) or short-wavelength (blue) regions of the visible spectrum. Although the properties of the cones are well known, the way in which they are functionally connected to nerve pathways for vision is not clearly understood. Clinical research has shown that reduced sensitivity to blue light is a feature of the early stages of certain visual diseases (for example, glaucoma), so it is important to know how the short-wavelength (blue) cones contribute to visual functions such as form, motion and colour perception. Such knowledge can help to design better tests for diagnosis of visual disorders, and will improve our understanding of the normal function of the visual system in the human brain. In this project the connections of neurones in the primate retina (the nerve cells which line the back of the eye) will be analysed. The blue cones and other nerve cells will be identified using contemporary anatomical methods (double- and triple-label immunocytochemistry) combined with a new method for high-resolution light microscopy, called deconvolution microscopy. Immunocytochemistry is a method borrowed from the field of immunology, where specific antibodies are raised which bind selectively to label specific populations of neurones. Deconvolution microscopy allows rapid and simultaneous visualisation of multiple labelled cell classes, at a resolution close to the limit of the light microscope. Together, these techniques allow the wiring diagram of the blue cones within the retina to be analysed to a higher level of accuracy than previously achieved. The results will improve our understanding of the role of blue-cone circuits in normal vision and visual disorders.Read moreRead less