The UCL Optical Brain Imaging System

BIOMEDICAL OPTICS RESEARCH LABORATORY

References

This is a selection of peer-reviewed articles describing experimental work undertaken with the UCL system.

PDFs are available on our website (details overleaf).

1. Everdell NL, AP Gibson, IDC Tullis, T Vaithianathan, JC Hebden, DT Delpy (2005) A frequency multiplexed near infrared topography system for imaging functional activation in the brain Review of Scientific Instruments 76, 093705 2. Correia T, A Banga, NL Everdell, AP Gibson, JC Hebden (2009) A quantitative assessment of the depth sensitivity of an optical topography system using a solid dynamic tissue-phantom Physics in Medicine and Biology 54 6277-6286

THE UCL OPTICAL BRAIN IMAGING SYSTEM

3. Correia T, Lloyd-Fox S, NL Everdell, A Blasi, C Elwell, JC Hebden, A Gibson (2012) Three-dimensional optical topography of brain activity in infants watching videos of human movement Physics in Medicine and Biology 57 1135-1146 4. Lloyd-Fox S, A Blasi, NL Everdell, CE Elwell, MH Johnson (2011) Selective cortical mapping of biological motion processing in young infants Journal of Cognitive Neuroscience 23(9), 2521-2532 5. Lloyd-Fox S, A Blasi, A Volein, N Everdell, CE Elwell, MH Johnson (2009) Social Perception in Infancy: a near infrared spectroscopy study Child Development 80(4), 986-999 6. Blasi A, S Fox, N Everdell, A Volein, L Tucker, G Csibra, AP Gibson, JC Hebden, MH Johnson, CE Elwell (2007) Investigation of depth dependent changes in cerebral haemodynamics during face perception in infants Physics in Medicine and Biology 52, 6849-6864 7. Cooper RJ, NL Everdell, LC Enfield, AP Gibson, A Worley, JC Hebden (2009) Design and evaluation of a probe for simultaneous EEG and near-infrared imaging of cortical activation Physics in Medicine and Biology 54, 2093-2102 8. Cooper RJ, D Bhatt, NL Everdell, JC Hebden (2009) A tissue-like, optically turbid and electrically conducting phantom for simultaneous EEG and near-infrared imaging Physics in Medicine and Biology 54, N403-N408 9. Cooper RJ, Hebden, JC, O’Reilly H, Mitra S, Mitchell A, Everdell NL, Gibson AP, Austin T (2011) Transient haemodynamic events in neurologically compromised infants: a simultaneous EEG and diffuse optical imaging study Neuroimage 55(4), 1610-1616

More information can be found at:­ www.ucl.ac.uk/medphys/topography If you have any questions or would like to discuss your requirements, please contact: Dr Nick Everdell Department of Medical Physics & Bioengineering University College London Gower Street, London WC1E 6BT t: +44 (0)20 7679 0267 e: n.everdell@ucl.ac.uk

An advanced brain-mapping system designed and built

by Europe’s leading biomedical optics research group performs non-invasive imaging of brain activity in real-time.

• Applications

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Several research groups around Europe are already using our system.

It has been used in developmental psychology studies (e.g. investigating babies’ responses to functional and cognitive tasks3,4,5,6 and the development of language in children) as well as in neonatology (e.g. the response of premature babies to pain and the monitoring of neonatal seizure7,8,9).

It is also being used to study brain injury in adults. But this is just the start; it will be useful to researchers in many related fields.

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• The technique

Optical Topography combines the ease-of-use, low cost and portability of EEG with the imaging capabilities of fMRI. It uses near-infrared light to carry out functional imaging of the brain in real time. An array of optical fibres placed on the scalp measures cortical changes in blood volume and oxygenation using the characteristic infrared absorption spectra of oxygenated and deoxygenated haemoglobin.

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The same data can also be processed into various types of images to highlight changes in haemoglobin oxygenation or concentration. The images below depict the left and right temporal regions of the baby’s brain during the previous experiment. The left temporal region responds much more strongly to the face stimulus than the right side.

• Tried and trusted technology

• The UCL system

Our system, developed at the Biomedical Optics Research Laboratory (BORL), is borne out of 26 years of research excellence. Two wavelengths of infrared light are injected at 16 different points on the subject’s head, and the diffused light is measured at 16 separate detection points.1,2 The system can be easily configured to study adults, children or neonates, thanks to a sophisticated illumination technique that allows completely flexible positioning of the light sources and detectors. A foam-covered pad is used to apply the optical fibres firmly but comfortably to the subject’s head, and the entire system is controlled via an easy-to-operate graphical user interface. We can supply our system (full size or bespoke) at lower cost than our commercial competitors, and our customers benefit from on-going access to our expertise.

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• Data analysis

Each source-detector pair forms a ‘channel’. The data can be presented by channel to show how haemoglobin oxygenation and concentration change with time at various locations across the head.

This is equivalent to performing many individual nearinfrared spectroscopy measurements at multiple brain sites simultaneously, and the system is capable of acquiring up to 20 whole-cortex images per second.

The diagram above shows one possible arrangement of optical fibre bundles, placed over the left and right temporal regions of the head of a four-month-old baby. The baby was alternately shown pictures of a woman’s face and a mechanical digger, each for several seconds, for a few minutes in total.

The graph above right plots the concentrations of oxygenated, deoxygenated, and total haemoglobin with time for one particular channel. This reveals a rise in oxyhaemoglobin concentration in response to the face stimulus, along with a slight drop in deoxyhaemoglobin concentration.

To date we have built ten systems for various groups around Europe: the Ecole des Hautes Etudes in Paris, the Central European University in Budapest, the Donders Institute in Nijmegen, Manchester University, University of East London, King’s College Hospital in South London, Babylab at Birkbeck College (part of the University of London) and of course our own group at UCL. One of our systems is being used to study the effect of malnutrition on the cognitive development of children in the Gambia – this project is funded by the Gates Foundation.

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