New paper(s)

We have new papers out in press or in preprint!

The first is just out in Neuropsychopharmacology [here] from a long running collaboration with Eli Lilly, lead first by Soon-Lim Shin and then expertly shepherded to completion by Emilie Werlen. We used oxygen amperometry in freely-moving rats and found that haemodynamic signals in nucleus accumbens and orbitofrontal cortex during probabilistic learning reflect signed and unsigned prediction errors respectively. Moreover, both of these signatures were disrupted by a hyperdopaminergic state induced by acute amphetamine. This paper is dedicated to Soon-Lim who sadly passed away to cancer in 2017.

The second is a preprint [here], constituting a large body of Clio Korn’s thesis work (and a heroic number of hours spent collecting the data), investigating the influence of different dopamine clearance mechanisms on decision making strategies and dopamine release. She showed that the precision of striatal dopamine signalling, through DAT, has a selective role in shaping behavioural flexibility only when reward probabilities change, but not if action-state transitions are altered.

Last but certainly not least, Caroline Jahn’s re-analysis of local coeruleus and midbrain dopamine neuronal data collected by our collaborator Sebastien Bouret’s lab is also out as a preprint [here]. She uncovered intriguing differences between putative dopamine neurons that care most about the immediate decision to engage based on future reward versus noradrenergic neurons that also encode the likelihood of future engagement after an error. Moreover, the latter were also sensitive to changes in task state.

Welcome to Mason and George!

We delighted to have two new people, Mason Silveira and George Jenkins, join the lab. Mason was awarded a 2-year Canadian post-doctoral fellowship while George is just starting a 4-year iCASE DPhil, sponsored by Lundbeck. Both will be working on different aspects of understanding circuits for choosing when to initiate and when to withhold actions.

New paper in Nature Communications!

Our collaborative work with Heiko Backes and Rachel Lippert at the MPI Cologne is out in Nature Communications! We helped validate their model for monitoring dopamine levels with PET at single minute resolution by using fast-scan cyclic voltammetry to monitor fast and slow fluctuations in dopamine following chemogenetic activation. A great collective effort at our end from Clio to get the first data set, Lauren to follow this up when revisions were needed, and Tom JP to re-write the analysis code to look at transient detection and longer timescales of dopamine release.

New preprint about our open source photometry hardware

We’re excited to have put out a preprint demonstrating and validating a new open source Python based hardware and software for fibre photometry. This is the brainchild of Thomas Akam, and follows close on the release of pyControl, a package for implementing rodent behavioural experiments that he was instrumental in establishing in the lab. All the relevant design files and documentation are already online for anyone to use. Both are good and much cheaper than equivalent commercial kit.


We had the pleasure of hosting an "In2Science" student, Zach Morris, for the first time this summer.  Zach got to try his hand at everything from threading electrodes and make optic fibres to genotyping and spike sorting.  He even got to demonstrate that he was definitely better than a rat on one of the tasks that they are currently performing!  We really enjoyed having Zach around and hope to host another student next year.

Congratulations Lauren!

Many congratulations to Lauren who has been awarded a National Science Foundation Postdoctoral fellowship starting in August, to work out the mysteries of cholinergic interneurons with Steph Cragg's lab and us. 

Congratulations, Sebastian!

Many congratulations to Sebastian who has been awarded a prestigious Junior Research Fellowship at Merton College.  This provides 3 years of salary for him to pursue whatever research he wants, plus of course 3 years of free lunches and dinners so he will never go hungry.

Farewell Clio!

After nearly nearly 5 years in the lab and many hours spent over an FCV rig in our surgery coaxing dopamine out of frontal cortex (and almost coming round to a perspective that it should be called "frontal" and not "prefrontal" cortex), Clio has returned back to California to take up a post-doctoral position in Vikaas Sohal's group at UCSF.  We'll all miss greatly her boundless good cheer, unprecedented organisational skills, and ability to hit the VTA with her eyes closed.

Welcome to Hironori and Nils

A very warm welcome to two new lab members.  Hironori joins us on a Japanese Uehara Foundation scholarship to work on dopamine and decision making over the next year.  Nils is doing a 3-month rotation in the lab as part of his MSc Neuroscience course, working with Xudong to continue investigating how rats learn structure and how this is represented neurally.

Walton Lab do Brain Diaries Demos

The Walton Lab was out in force on Saturday as part of the Brain Diaries exhibition at the Natural History Museum in Oxford.  Visitors got to play a "Dopamine Dipper" marbles game to learn about prediction errors, and experienced a "Heavy Feet Challenge" as a platform to discuss how dopamine influences motivation, effort and decision making.  Most importantly, all attendees were thoroughly disabused of any ideas from the media that dopamine is necessary for pleasure and happiness.

Congratulations, Clio!

Many congratulations to soon-to-be Dr Clio who successfully defended her D.Phil thesis on the role of different clearance mechanisms on patterns of dopamine release and motivated behaviours!

Welcome to Iñes, Sebastian and Veronika

A very warm welcome to a cornucopia of talented MSc students rotating with the lab for the first 3 months of the year.  Iñes is working with Xudong and Cheng to see how rats build models of the world, Sebastian is investigating the pharmacology of self-control in rats with help from Laura, and Veronika is looking at glutamate-dopamine interactions during habituation in mice with Marios and Tom JP. 

Welcome to Emilie!

We are delighted welcome to Emilie Werlen who has joined the lab as a post-doctoral fellow.  Emilie recently finished a PhD with Dr Matt Jones at the University of Bristol where she focused on the influence of mesocortical dopamine projections on neural activity patterns in different brain states and cognition.  In Oxford, she will be working on analyses of electrochemical data and leading a project to determine the precise temporal relationship between dopamine release and action initiation.

1st post-doc advert now live

Applications are now live for a highly motivated postdoctoral research associate to take forward a new 5-year Wellcome Trust-funded project to investigate the precise causal role of dopamine release in the regulation of reward-guided action selection.  The post is initially a 3-year fixed-term appointment with the possibility of renewal up 5 years, with a start date of 1 November 2016 (or as soon as possible thereafter).  Closing date is 7th October, 2016.

The primary role of the researcher will be to take forward and develop a programme of work aimed at unravelling the moment-by-moment role of dopamine release in decisions to act or not to act. To do this, the project will use state-of-the-art techniques to record and/or manipulate sub-second dopamine in rodents performing sophisticated reward-guided decision making tasks. There will also be the potential to use computational modelling to better understand the relationship between real-time dopamine release and animals’ behaviour.

Candidates should have attained, or be nearing completion of a PhD in a relevant discipline and/or have relevant postdoctoral experience.  Experience with rodent neurosurgery, in vivo recording and/or optogenetic tools (preferably in behaving rodents) is essential along with excellent organisational and record keeping skills.

Informal enquiries to Mark are encouraged.  More details and formal applications can be found here and on the central Oxford recruitment portal here (job ref: 125281).  One other similar position will also come available in the next 6-12 months.

New post-doc positions

Following the award of Mark's SRF, 1-2 new post-doc positions will be opening up shortly.  We'll be looking for talented people with experience of using optogenetics, chemogenetics and physiological recording to understand reward-guided behaviours.  Any interested candidates should first email me directly.