Improving the reproducibility of brain stimulation and brain connectivity through collaboration
Brain stimulation methods comprise a set of powerful and unique tools to measure and modulate brain activity. By electrically or magnetically stimulating a precise area of brain at a precise time during a behaviour, psychologists and neuroscientists can probe the workings of healthy human brains in ways that were previously inaccessible to psychology (Sandrini et al. 2011). For example, by stimulating the brain between the presentation of a stimulus and making a response, we can perturb, and therefore understand, the mechanisms of human decision making. Brain stimulation can also be used to enhance our understanding of neurodiverse conditions.
However, for this potential to be fully realised, it is essential that we first establish the protocols in neurotypical individuals. Despite the potential power of such methods, the weakest link is often the human operator. The ‘replication’ or ‘reproducibility’ crisis has affected brain stimulation research just as much as it does the rest of psychology and all other sciences (Corp et al. 2021). Fortunately, the solutions to the replication crises are within our grasp – systematic study, open science, replication & collaboration.
This doctoral research project will focus on documenting and improving the reproducibility of transcranial magnetic brain stimulation (TMS) studies of connectivity between motor cortex and other brain areas. When a TMS pulse is presented over one brain area – say, the premotor cortex - followed shortly after by a second pulse over the motor cortex, the neural connectivity between premotor and motor cortex can be inferred from the effect of the first pulse on the response to the second.
The motor cortex provides a unique model system for developing TMS research on other areas. With every pulse of TMS over M1, a reliable and quantifiable output from the body’s muscles is given. This one-to-one input-output relationship makes TMS research particularly attractive. We now know a great deal about motor cortex from nearly 40 years of this form of TMS research, but we know much less about how the rest of the brain responds to TMS. TMS connectivity research, by linking a particular brain area with M1, can therefore provide a bridge between the workings of the rest of the brain and the reliable outputs from M1.
The aims of the PhD project are therefore to:
1) Systematically review and meta-analyse the literature on TMS connectivity with M1 (Year 1)
2) Summarise, develop and test best-practice protocols for TMS connectivity studies (Years 1-2)
3) Instigate and manage a ManyLabs reproducbility project for TMS connectivity (Years 2-3).
The proposed time-line is:
Year 1: Induction; systematic review & meta-analysis; training; piloting; pre-registration; experiments; establishing collaborations; writing
Year 2: Further experiments; growing collaborations; conference; update meta-analysis
Year 3: Final experiments; update meta-analysis; writing; large collaborative research paper; conferences & workshops
References
Corp, D. T., Bereznicki, H. G. K., Clark, G. M., Youssef, G. J., Fried, P. J., Jannati, A., Davies, C. B., Gomes-Osman, J., Kirkovski, M., Albein-Urios, N., Fitzgerald, P. B., Koch, G., Di Lazzaro, V., Pascual-Leone, A., & Enticott, P. G. (in press, 6 July 2021). Large-scale analysis of interindividual variability in single and paired-pulse TMS data. Clinical Neurophysiology. https://doi.org/10.1016/j.clinph.2021.06.014
Sandrini, M., Umiltà, C., & Rusconi, E. (2011). The use of transcranial magnetic stimulation in cognitive neuroscience: a new synthesis of methodological issues. Neuroscience & Biobehavioral Reviews, 35(3), 516-536.