The use of focused magnetic pulses to stimulate the brain, a technique known as transcranial magnetic stimulation or TMS, is now becoming commonplace in neuroscience research.
It allows researchers to slightly alter the function of a brain area using a hand held magnetic coil. The resulting changes can hopefully be detectable using behavioural or psychological measures.
Like most neuroscience studies, research projects using this technique start by wondering whether a particular brain area is necessary for a particular type of mental activity or behaviour.
Unlike other techniques, such as brain scanning – that typically only find correlates of thought or behaviour – TMS allows researchers to make causal inferences. In other words, they can judge whether the area they are targetting is involved in causing the thought or action to occur.
Traditionally, TMS is used in research to safely inhibit or disrupt function in a brain area for a short period of time. More recently, it has been found that TMS (particularly when given in ‘trains’ or repetitive bursts) can be reliably used to increase activation in brain areas, over longer time periods.
The PloS Biology study targetted an area of the brain involved in somatosensory functions (mainly touch and body image) and found that they could increase skin sensitivity on the finger, when they aimed for the brain area that holds the ‘finger map’.