PhD studentship in Atomic or Medical Physics or Engineering to work on Imaging brain function with Electrical Impedance Tomography and atomic magnetometers.

Background. Electrical Impedance Tomography is a new medical imaging method which enables images of the internal electrical impedance of a subject to be produced with arrays or external electrodes. Originally developed for imaging lung ventilation, it has unique potential in imaging the brain and nerves, where it can provide images of fast electrical activity over milliseconds not possible by any other method. This project is to extend its use to imaging brain function by designing a novel specially adapted atomic magnetometer.

Its applications in Neuroscience have been pioneered by a multidisciplinary bioengineering/neurophysiology research group in Medical Physics at University College London, headed by Prof. David Holder, a Neurologist and Biophysicist, and Dr. Kirill Aristovich, a Bioengineer. Fast neural EIT has been successfully developed for imaging electrical circuit activity in the brain over milliseconds in 3D. Similar images can be acquired during evoked activity in nerves. This is currently not possible by any other method. It can also image slower changes over seconds, similar to fMRI. The instrumentation currently resembles an EEG system, with benchtop hardware similar to a small-form PC (2). This links to flexible silicone rubber electrode mats placed surgically on the brain (1,7) or ultrathin depth electrode shanks. Images are acquired by averaging over a few minutes in response to a repeated stimulus such as a flashing light for the brain. Resulting images have a resolution of 1 msec in time and <0.2 mm in space in peripheral nerves (5) or the brain (3,6). The group has a wide range of skills, in biology and medicine for experimental design and analysis, electronic and mechanical engineering for instrumentation development, maths for image reconstruction, physics for experiments and modelling, and chemical engineering for electrode design. The group has good links with industry. Brain applications are in collaboration with companies in Neural Engineering, and international research groups in Harvard and Columbia Unviersities USA, developing microelectrodes for recording brain and nerve function, miniaturising the hardware with a major international Electronics manufacturer, and optical coheherence tomography (OCT) as a complementary method.

Project work. At present, EIT in the brain has been shown to produce images of circuit activity in anesthetised rats with intracranial electrodes. The original vision was to achieve this with only external EEG type electrodes on the scalp. Conventional EIT images are produced by injecting a small current that cannot be felt and recording the resulting voltages. Unfortunately, the skull acts as a barrier so EIT has only been posible with electrodes placed surgically on or in the brain. The aim of this project is to achieve the original vision with the use of atomic magnetometers (also known as optically pumped magnetometers, "OPMs"). These can measure the tiny magnetic fields produced naturally by the brain (9) and appear as cubes about 1cm³, placed on the scalp. We propose they could be used to record magnetic fields produced in brain EIT. As the skull is transparent to magnetic fields, this should allow the original vision of non-invasive EIT of brain circuit activity with a cycle helmet like apparatus containing EEG electrodes and OPMs. OPMs for human use are already available but need to be modified to enable fast neural EIT which operates at a higher frequency.

The researcher will work in a multidiscplinary team with a neuroscientist and physicist already engaged in the project. The main work will be to build an OPM able to operate at the optimal frequency for EIT of c. 2kHz. This may be by design from scratch of by modification of an existing design. It will require a background in physics or engineering, preferably with quantum physics, and an interest in technology development and testing in an interdiscplinary environment. Full training and support will be given in aspects of bioengineering and also relevant quantum physics and OPM design. The appoiintee will also contribute to development and refinement of OPM-EIT in the light of studies in saline filled tanks, anaethetised rats and then human studies.

Applications are sought from outstanding candidates with a 1st class Honours degree or an MSc in physics, or engineering, but related subjects relevant to this work are also welcome. It is only definitely funded for students who would qualify for UK PhD fees; it may include overseas fees for outstanding international applicants. It will suit candidates who like a challenge and to work in a multidisciplinary team. This research will be based in Medical Physics at UCL, and may include work on human subjects at nearby hospitals in London, and may be jointly with industry.

To make an application, please email your CV and a covering letter to: Prof. David Holder ([Email Address Removed]) explaining your interests and any research experience.