Ewch i’r prif gynnwys
Dr John Evans B.Sc (Bristol) Ph.D. (Exeter) CPhys

Dr John Evans

B.Sc (Bristol) Ph.D. (Exeter) CPhys

MRI Research Fellow & MRI Lab Manager

Yr Ysgol Seicoleg


Research summary

As the Chief Physicist of the Magnetic Resonance lab in  CUBRIC, I am responsible for the optimisation of our 3 Tesla MR system for use  as a tool for neuroimaging research, for example by the implementation of novel  pulse sequences.  This role also involves  advising on experimental design and analysis across the whole range of MR  methods – structural and functional imaging and spectroscopy.

My research interests include:

MR Spectroscopy

Evaluating the robustness       of GABA measurement in vivo.

The optimisation of       analysis methods for GABA spectra, and the development of a toolkit for       the analysis of GABA data (Gannet)


Working on hardware       improvements to allow the integration of transcranial magnetic stimulation       into the MR environment for simultaneous TMS and functional MRI.


Undergraduate education

1995 B.Sc in Physics (University of Bristol)

Postgraduate education

1999 Ph.D. in Physics (University of Exeter)
2002 Chartered Physicist (Institute of Physics)


2007-present.       Chief Physicist, CUBRIC, School of Psychology,  Cardiff University, UK
2004-2007.          MR  Physicist, Department of Psychiatry, University of Oxford, UK
2000-2004.          MR  System Design Engineer, GE Healthcare, Abingdon, Oxford, UK
1999-2000.          MR  System Design Engineer, Magnex Scientific, Abingdon, Oxford, UK


















Research topics and related papers

Repeatability of GABA Spectroscopy

There is a significant amount of research demonstrating that the inhibitory neurotransmitter γ-aminobutyric  acid (GABA) is a useful biomarker for psychiatric disorders.  Recently, work  at the School of Psychology at Cardiff has demonstrated that the measurement of  GABA concentration in the human brain is sufficiently sensitive to explain  individual differences in a variety of behavioural tasks (e.g. Sumner et al,  Nature Neuroscience, 2010, Boy et. al. Current Biology, 2010), and in  personality traits (Boy et. al. Biological Psychiatry, 2011).

However, the measurement of neurotransmitters using edited  MR spectroscopy is inherently insensitive, compared with imaging techniques.

For example, the concentration of GABA is approximately 50,000 times  lower than the concentration of water, resulting in longer experiment times and  larger voxel sizes than are achievable in imaging experiments.  As a  result, characterising the robustness of the experiment is very important,  particularly as this can vary significantly between brain regions.


As part of this research, I have been optimising the  analysis method for GABA spectroscopy and, along with Richard Edden (Johns  Hopkins University, Baltimore) we have incorporated this into a set of  Matlab-based tools (the GABA Analysis Toolkit, "Gannet") which is currently being distributed to collaborating  sites, prior to general release [link].

Research collaborators

Fred Boy
Chris Chambers
Richard Edden (Johns  Hopkins University, Baltimore)
Derek Jones
Paul Keedwell
David Linden
David McGonigle
Suresh  Muthukumaraswamy
Nick Puts (Johns  Hopkins University, Baltimore)
Krish Singh
Petroc Sumner
Richard Wise


Past projects

Media activities

As  the School's Welsh language officer, and a fluent Welsh speaker, I am keen  to bring neuroimaging to the public through the medium of Welsh.  I have  appeared on the following programmes to attempt to raise the profile of CUBRIC  and the School of Psychology to a Welsh speaking audience:

BBC  Wales News & Newyddion BBC Cymru, March 2008. Appearance on a local news  item (both English and Welsh language versions) reporting the study into  structural brain changes associated with acute mountain sickness.

“Mosgito”,  BBC Cymru, September 2008.  Appearance  discussing how fMRI can be used to localise activity in the brain on  Welsh-language magazine programme aimed at 12-15 year olds.

“Y  Daith” (“The Journey”), S4C,   November 2009.  Appearance on the  S4C programme discussing the effect of brain structure on an individual’s risk  of alcoholism.

“The Brain: A Secret History”.  BBC Four, January 2011.  Appearance and filming support for the BBC  Four programme documenting a research study investigating the effect of  hallucinogenic drug psilocibin using functional MRI.

“I’r  Eithaf” (“To the Extreme”), S4C, November 2011.  Appearance on children’s TV programme running  a set of functional MRI experiments on the show’s presenter, to discuss the how  the brain processes.