By using simultaneous brain stimulation and activity recording to track the influence of one brain region on another, researchers have developed a new method for boosting brain function that may have implications for treatments of brain disorders and for improving vision. The findings are reported by Christian Ruff, Jon Driver, and their colleagues at University College London and appear in the August 8th issue of Current Biology, published by Cell Press.
In their new work, the researchers used trans-cranial magnetic stimulation (TMS) to trigger a chain of activity in specific parts of the brain, while the activity was measured with a scanner. In this way, they were able to show that stimulating a particular region of the frontal cortex that is normally involved in generating eye movements can change activity in visual cortex, almost as though an eye movement had been made (even though the eye itself stayed still).
Perceptual tests confirmed that this brain stimulation had the effect of enhancing peripheral vision, as if people could now see better out of the corner of their eye.
Brain stimulation with TMS is beginning to be used in the treatment of various neurological conditions, including those, such as the after-effects of a stroke, that can impair vision. The technical breakthrough reported by the UCL group means that it is now possible to study the underlying brain activity triggered by TMS, both in the healthy brain and in patients with brain damage.
The researchers include Christian C. Ruff, Felix Blankenburg, Otto Bjoertomt, Sven Bestmann, Elliot Freeman, Geraint Rees, Oliver Josephs, Ralf Deichmann, and Jon Driver of the University College London in London, United Kingdom; John-Dylan Haynes of Max-Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany.
This work was supported by the Wellcome Trust, the Biotechnology and Biological Research Council, and the Medical Research Council (UK). J.D. holds a Royal-Society-Wolfson Research Merit Award.
Ruff et al.: "Concurrent TMS-fMRI and Psychophysics Reveal Frontal Influences on Human Retinotopic Visual Cortex." Publishing in Current Biology 16, 1479–1488, August 8, 2006, DOI 10.1016/j.cub.2006.06.057 www.current-biology.com
Related Dispatch by Kayser et al.: "Vision: Stimulating Your Attention."