Take home messages:

  • The promise of TMS for treating neurological disorders is being tested in two major clinical trials.
  • Early studies have hinted at the possibility of tRNS to substantially enhance cognition, especially in people who start at a lower level of ability.
  • Combining brain stimulation with brain imaging has led to exciting new perspectives in cognitive neuroscience.

The seventh annual meeting of this series of conferences on brain stimulation was held in Oxford’s imposing Examination Schools. The meeting place is only a short walk from the home of Thomas Willis, who in the mid seventeenth century coined the term ‘neurology’ and produced the first functional anatomical atlas of the brain. Willis’ house should be a site of pilgrimage for delegates at this meeting.

The organising committee for this meeting was the same as that for the previous meeting (see ACNR vol. 12 issue 3, p28): Prof. Vincent Walsh (UCL), Dr Charlotte Stagg (Oxford) and Dr Sven Bestmann (UCL). As before the meeting was sponsored by Magstim, manufacturers of devices for non-invasive brain stimulation (magstim.com), but the scientific committee was given complete independence in organising the topics and the speakers. The two main techniques of brain stimulation were represented: transcranial magnetic  and current stimulation (TMS, tCS). In addition a series of workshops gave participants hands-on experience with the equipment and techniques.

 Day 1

The meeting opened with a session on “Integrating methods in cognition”. Antonio Strafella (Toronto) demonstrated the promise of combining TMS with positron emission tomography (PET) to understand dopamine transmission in cognitive circuits. His and others’ work shows how PET can be used to study stimulation-related dopamine dynamics in the striatum in healthy cognition and in Parkinson’s disease. The second talk, from Marom Bikson (City University of New York), addressed an important topic in brain stimulation: how to understand the effect of stimulation on the brain. Bikson uses finite element modelling to estimate the electric field on the brain surface during tCS. With this technique he and others have designed new electrode montages for focusing tCS, and have studied individual differences in brain anatomy and response to stimulation; with these advances there is hope for individualised targeting and dosing of tCS.

Simone Rossi (Siena) touched on a recent debate in the brain imaging community: how can fMRI and related techniques inform cognitive neuroscience? One solution is to use brain stimulation to explore the causal role of brain areas that appear to be active during scanning. Rossi and colleagues have done this in studying different models of human memory. Alex Sack (Maastricht) continued the theme of combining brain stimulation with imaging techniques, this time in the study of visual perception and cognition.

The second session dealt with “Clinical applications and depression”, a topic of particular relevance since at present the only disorder for which brain stimulation is approved as a treatment in the USA is depression. The first speaker, Richard Carson (Trinity College Dublin), addressed the seeming heterogeneity in individual responses to brain stimulation. While differences in brain anatomy are known to affect efficacy (as Marom Bikson had discussed earlier), Carson focused on genotypic differences, in particular different forms of the gene for the precursor protein for brain-derived neurotrophic factor (pro-BDNF), which is known to be involved in short- and long-term plasticity in brain function. This will have important implications for determining who will respond most favourably to brain stimulation as an intervention. The next two speakers, Linda Carpenter (Brown) and Klaus Ebmeier (Oxford), both dealt with TMS as a treatment for depression. Two major trials in the USA, NeuroStar and OPT-TMS, are generating important knowledge about dose and efficacy for TMS treatment of depression, and are showing promising results.

The day concluded with a poster session, in which exciting new results were presented by the large number of junior researchers who attended the meeting. Later that evening a dinner was held in the beautiful old hall of Wadham College, at tables formerly frequented by generations of scientific pioneers.

Day 2

The second day started with a session entitled “Cognition and enhancements”, which promised much excitement. Nor were we disappointed: the first speaker, Roi Cohen Kadosh (Oxford) presented work on improving mathematical abilities through the use of transcranial random noise stimulation (tRNS). Although Cohen Kadosh acknowledges that his studies are based on small numbers of participants, nevertheless these early results show highly promising improvements in numerical reasoning with seemingly no side-effects. These improvements were particularly evident in people with lower abilities at the start of the trial, which implies the possibility of negating any disadvantages experienced by people entering education at a lower level of attainment.

Lorella Batelli (Harvard) then discussed enhancing perceptual functions in people with damaged brain tissue. Improving perception also helps us to understand healthy perceptual processing. In particular Batelli highlighted the so-called “when” pathway in the brain, that supports temporal judgements. The third speaker of this session was Marinella Cappeletti (UCL) who talked about the effect of ageing on efficacy of brain stimulation. Since many clinical applications of brain stimulation involve disorders associated with older age, such as stroke or Parkinson’s disease, it is important to know how the older brain responds to stimulation. Using a simple numerosity judgement task, Cappeletti showed that people improved when given tRNS. However when the participants were tested on an untrained but related task, such as temporal judgement, younger participants in the tRNS group improved in these tasks but older participants showed worse performance. This is an important consideration in using brain stimulation as a treatment.

The final session of the meeting was a chance to recognise outstanding achievements. The Magstim Senior Investigator Prize was awarded to Salvatore Aglioti (Rome) for his study of corticospinal excitability during action observation in experts and non-experts. The Magstim Young Investigator Prize was won by Matteo Fuerra (Siena) for studying transcranial alternating current stimulation (tACS). Finally James Dowsett (Oldenburg) won the Magstim Poster Prize with work on the instantaneous effects of tACS on cortical excitability.

Conclusion

Once again the Magstim conference has shown itself to be the premiere annual meeting for brain stimulation research. The organisers balanced the most exciting developments in technical, scientific and clinical domains to produce a programme that was exciting, educational and, to risk a pun, stimulating.

To register your interest in the 2014 event Email: joseph.durrant@magstim.com

ACNR 2013; 13:4:34-35