Contact details

Dr Stephen L Hicks

Honorary Research Associate
Division of Neurosciences and Mental Health

Tel: +44 (0)20 8846 7289
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Dr Stephen L Hicks

My interests are in systems neuroscience, that is, trying to understand how behaviours are manifest through the brain-wide coordination of perceptual, decision making and motor control centres. My research covers areas such as: the control of eye movements and saccades, visual perception, basal ganglia function - particularly in Huntington's Disease, and visual recovery from stroke.

Illustration of the visual and oculomotor streams

Oculomotor deficits in Huntington's Disease

The oculomotor deficits associated with Huntington's Disease (HD) are one of the earliest signs of disease onset. They include a marked delay in executing voluntary saccades and a difficulty inhibiting saccades to task-irrelevant stimuli. In addition, HD patient develop a delay in task-switching, which can be demonstrated by the adherence to a prior rule when the rule has been recently changed. These deficits are likely to be the result of a progressive neural degeneration of the fronto-striatal system, which is a distinguishing feature of HD neuropathology. It is predicted that as the disease progresses the magnitude of these specific deficits should increase. We find that when patients are tested on a test of saccadic inhibition and rule switching, saccadic latencies and error rates in early HD patients were found to be systematically higher than pre-symptomatic subjects.

The implementation of this experiment, particularly in a clinical environment, was made possible by using a Saccadometer (Ober Consulting). This is a light weight, head mounted, infrared eye tracker with built in stimulus delivery.

We have contributed an oculomotor paradigm to the Track-HD study which is a longitudinal multi-centre, multi-national prospective, observational biomarker study of premanifest and early stage HD. Track-HD includes a range of functional markers, including structural MRI (1.5 and 3T) cognitive, psychological and quantitative assessment, as well as bloodborne metabolic markers.

Conference poster: Oculomotor deficits indicate the progression of Huntington's Disease

Visual search training for Hemianopia patients

In our laboratory we have been working on a semi-interactive DVD that may encourage rehabilitation from hemispheric visual neglect (Hemianopia). Using a visual search paradigm, patients are enouraged to make more and more saccades into their neglected field, thereby gradually increasing their awareness of objects in this area.

Simulation of a retinal prosthetic

With Dr Patrick Degenaar and Walid Al Atabany of the Insititute of Biomedical Engineering we are designing a wearable system that may simulate the experience of using a retinal prosthetic. Using a combination of eye tracking a head-mounted display and real-time visual feature enhancement we plan to test the perceptual parameters of subjects experiencing a greatly reduced field of view. With the miniturisation of electrode arrays and reduction in power consumption of these devices, retinal prosthetics are likely to become a real treatment for certain types of blindness. The computer systems that drive the image presentation will be crucial in the take-up and experience of the future users.