PhD studentship 2015

I have a PhD Studentship available for September 2015, funded by EastBIO:

Visual processing of 3-D motion in healthy ageing

The processes used by our brains to perceive objects moving in three dimensions (3D) are fundamental to understanding human vision. This PhD will form part of a project in the Harris lab that is aimed at exploring whether the location, trajectory and identity of objects moving in depth are extracted by different visual pathways, and if so, whether the information carried by different pathways is used for different purposes. Julie Harris is a world-leading expert on the perception of 3-D motion (eg. see Harris, 2004) and will be the primary supervisor. The project will be co-supervised by Karin Pilz (University of Aberdeen) who is an authority on visual motion perception in healthy aging. The work will be carried out in St. Andrews, but there will opportunity for regular visits to Pilz’s lab in Aberdeen. The student will benefit by being closely linked to these two groups, each of which have currently funded BBSRC grants in this area.

Binocular vision allows for two potentially separate sources of information about motion in depth (MID). These are changing binocular disparity (CD) and a combination of left and right eye monocular motion signals (inter-ocular velocity difference, IOVD, see Harris, Nefs & Grafton, 2008)). CD signals must be derived from disparity-detecting neurons in visual area V1. IOVD processing is more mysterious. It requires a combination of monocular motion signals. These could originate from monocular neurons in V1, but equally could be based on motion signals that bypass V1, via the koniocellular pathway.

One way to explore the relative importance of these pathways is to explore vision in older observers. We know that there are specific deficits in motion perception that appear as we age, and which would likely impact on our ability to perceive MID via the IOVD processing pathway. Although binocular visual function also declines with age, deficits are typically not as severe as for motion specific pathways. We can therefore use the differences in expected performance in older observers as a tool to probe what pathways and processes are involved in the extraction of MID. We will use psychophysical behavioural techniques, combined with computational modelling of the two sources of visual information, to determine the accuracy and precision of perception of motion, binocular depth perception, and MID. Comparisons between older and younger adult populations will allow us to psychophysically dissect the neural pathways being used for these visual functions.

The project uses the natural differences between different sub-areas of vision, during aging, as a tool to understand normal visual function. We have already succeeded in using the individual differences between people to point to there being two mechanisms for MID perception (Nefs, O’Hare & Harris, 2010). The larger variability that is commonly seen within groups of older observers will deliver an advantage here, helping us to dissociate the two MID mechanistic pathways. The project will also provide us with valuable data about basic visual function in the aging population. MID is an important visual function of everyday life, necessary to navigate through the environment. Therefore, it is important to understand the mechanisms underlying age-related changes in MID. The results from this project will not only help to understand age-related changes in MID but, in the long run, might lead to the development of applications that help older adults to maintain their quality of life.

This opportunity is only open to UK nationals (or EU students who have been resident in the UK for 3+ years immediately prior to the programme start date) due to restrictions imposed by the funding body.

Apply by 5.00pm on the 16th January 2015 following the instructions on how to apply at: http://www.eastscotbiodtp.ac.uk/how-apply-0

Informal enquiries to Julie Harris are very strongly encouraged.

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