Two pieces of news from the CUBRIC TMS group.
First – I’m delighted to report that on Friday my first PhD student, Chris Allen, passed his viva with flying colours. A big thanks to his diligent examiners, Simon Rushton and Kia Nobre. Chris’ PhD addressed the neural basis of visual consciousness in humans, using an impressive combination of brain stimulation (TMS) and brain imaging methods (including magnetoencephalography and magnetic resonance spectroscopy). The thesis is full of interesting experiments, but for me the most intriguing discovery was that inhibiting the visual cortex with TMS can (paradoxically) enhance conscious perception. Chris is currently preparing several papers for submission and we’ll be sure to post Research Briefings on this blog once the work is published.
|Post-viva drinks with Chris (left) and his examiners, Simon Rushton (Cardiff) and Kia Nobre (Oxford)
Second – also on Friday – we heard that our BBSRC application, “Neural dynamics of response inhibition and gambling across the lifespan”, was successful. My sincere thanks to our grant assessors and BBSRC Research Committee A for supporting this project. And it's probably a good thing we didn't include this particular pearl of wisdom in the Pathways to Impact section (hat-tip to Mark Stokes).
This 3-year study extends work that we published in 2010 and 2012, and will take place in partnership with Frederick Verbruggen from the University of Exeter, John Evans at Cardiff University, Andreas Bungert from the Max Planck Centre in Tuebingen, and Sven Bestmann from UCL. In our previous experiments we looked at the psychology and neuroscience of cognitive control, focusing particularly on the ability to inhibit thoughts and actions (see here for the Research Briefing associated with the more recent of those projects).
Our BBSRC project seeks to discover how we control our impulses. Let’s say you’re in Las Vegas and have just won $200 on blackjack. The win is thrilling but you soon feel hungry for another hit. Do you stop and collect your winnings or risk what you’ve gained? And if you decide to resist temptation and stop gambling, what systems in your brain helped you arrive at that decision? One hypothesis is that the prefrontal cortex, our most advanced brain area, supports self-control by regulating the activity of deeper, more primitive neural circuits that – if left unchecked – would get us into a lot of trouble.
There is an interesting side note to this which I think is often understated in popular culture. We tend to think of the brain, intuitively, as a single system (perhaps because our own sense of self is unitary – i.e. there is only one “you”). But the reality is that different parts of our brains have evolved over very different time scales. The human brain didn't emerge from the mists of evolution as a whole entity. On the contrary, most of the older, deeper parts have been hanging around for a very long time, and the rest was built around them. These ancient areas are many millions of years old and are much the same in humans as in cats, mice and even birds. But the parts that truly ‘make us human’ lie in the neocortex, literally the ‘new’ part of the brain that evolved relatively recently. And the newest kid on the block is the prefrontal cortex, which we believe oversees all the other systems, including the unrulier deeper parts. Being a Johnny-come-lately has its advantages.
In the first phase of our BBSRC project we’re going to test how the prefrontal cortex regulates behaviour by stimulating it with TMS while people undergo a functional MRI scan to detect brain activity. Our reasoning is that if the prefrontal cortex controls primitive systems then when people are in the process of stopping a response, stimulating the prefrontal cortex at the right time should especially activate deeper areas. So we’ll be using TMS a bit like a torch in a dark room, lighting up the brain pathways that are important for inhibiting our impulses. We’re also going to apply this approach in younger and older adults to see how the normal ageing process alters these connections.
In the second part of the project we’re going to try and figure out why training people to inhibit simple motor actions reduces gambling behaviour. We already have an ESRC grant based in Exeter to study the psychological side of this question, but here with the BBSRC we’re going to tackle the neurological side. To do this we’ll measure brain activity after ‘inhibition training’ using functional MRI and a technique called magnetic resonance spectroscopy, which measures the concentration of various neurochemicals. There are reasons to think that one of these chemicals, a neurotransmitter called GABA, could be important for regulating behaviour. If so we should see an increase in GABA after inhibition training.
Also – I’m excited to report that all studies in this BBSRC project will be conducted according to the principles of open science. This means we’re going to publicly upload all of our proposed methods and analyses (in detail) prior to collecting data. Then once the experiment is complete we’ll upload the raw data themselves for free public access, including behavioural and brain-imaging data. The benefits of open science are enormous: by pre-registering our research the scientific community can be assured that our results aren’t cherry picked or massaged to find ‘statistical significance’ – and by providing the raw data we will allow others to explore the results in ways we hadn’t considered.
Finally, we will be advertising soon for a 3-year full-time research assistant to work on this project with us (starting in the new year). So if this project grabs your interest, do keep an eye on this blog and you can follow me on Twitter for immediate updates.