Research
Projects - Theme 1
Theme 1: Vision for Living: Eye and Brain
Theme Leader: T.D. Lamb
- Dark adaptation, of human retinal cells measured from the ERG
- Human psychophysical dark adaptation
- Mammalian rod photoreceptor shut-off kinetics
- Amphibian rod responses from single-photon to intense flash regime
- Multi-electrode recording of topographic organization of direction selectivity
- Brain regulation of retinal function in the bird retina
- Applications of multifocal methods to vision in disease and health
- Multimodal-multifocal analysis of the hierarchy of human visual cortical areas
- Organization and reorganisation of visual cortex
Dark adaptation, of human retinal cells measured from the ERG (Lamb)
The overall aim of this project is to measure the contribution of different retinal neurons to the dark adaptation recovery of the human visual system, by recording and analysing the electroretinogram (ERG). The significance of this research is that it will determine the changes in speed and sensitivity of response that occur at different retinal levels during recovery from intense bleaching exposures.
Human psychophysical dark adaptation (Lamb)
This project will combine ERG measurements with psychophysical investigations to compare dark adaptation in the retina with that in the entire visual pathway. This work will help clarify the extent to which the recovery of visual sensitivity in the photopic (cone) visual system is dependent on the presence/absence of visual pigment, and the presence of photoproducts (metarhodopsin, opsin, etc.).
Mammalian rod photoreceptor shut-off kinetics (Lamb)
Although the activation steps in vertebrate phototransduction are understood in great detail, the shut-off reactions are only understood in a more general and qualitative manner. This project seeks to obtain a quantitative understanding of the shut-off reactions underlying mammalian rod photoreceptor responses.
Amphibian rod responses from single-photon to intense flash regime (Lamb)
The aim of this study is to provide a convincing and quantitative molecular description of the responses of single rods that spans the range from single photons to hundreds of thousands of photons.
Multi-electrode recording of topographic organization of direction selectivity (Vaney)
Multi-electrode arrays will be used to examine the topographic organization of direction-selective ganglion cells in the rabbit retina, and to gain new insights into the complexity of information processing in both the mammalian and avian retina. Progress in this study will feed naturally into several projects in Theme 2 that are concerned with the analysis and use of optic flow information for visual guidance and navigation.
Brain regulation of retinal function in the bird retina (Vaney)
The great Spanish neurologist, Ramon y Cajal, discovered that that the retinae of ground feeding birds, like pigeons and chickens, receive a substantial efferent input from the brain. These centrifugal inputs from the isthmo-optic nucleus make calycal synapses on the somata of unusual axon-bearing interneurons in the inner retina. The function of this input is unknown but there are many indications that it is designed to provide very rapid feedback. This study will unravel the significance of these inputs. This project addresses one of the longest standing questions in visual neuroscience and the answers will be of wide interest to the visual science community.
Applications of multifocal methods to vision in disease and health (Maddess, James)
This study will use multifocal versions of visual evoked potentials, pupillography and functional MRI to examine visual function and dysfunction in patients with age-related macular degeneration, glaucoma, diabetic retinopathy, optic neuritis and other disorders affecting vision. Apart from its clinical value, this study will provide important inputs to a number of projects in Theme 3.
Multimodal-multifocal analysis of the hierarchy of human visual cortical areas (James)
Human vision involves feed-forward and feedback flows of activity between multiple levels of a hierarchy of visual cortical areas. These cortical areas have been extensively mapped in the macaque cortex, with a wealth of data from microelectrode recording from many of the areas. However, there is notably little data bearing on the physiological role of the inter-area feedback connections. This project will use multifocal visual evoked potential analysis and multifocal functional magnetic resonance imaging, and magneto-encephalography to develop a powerful functional human brain mapping methodology which will open a wealth of new studies in human cognitive neuroscience.
Organization and reorganisation of visual cortex (Dreher)
The response of the cortex to small lesions to the retina will be examined in immature and mature mammals, to gain insights into the principles of cortical processing of vision, and to understand perceptual distortions in human patients.
>> Theme 2: Vision for Action and Robotics
