Study highlights effect of brain waves on human behaviour
Boosting a certain type of brain wave can slow people's movements, UK researchers have discovered. The findings, published online by the journal Current Biology, offer the first direct evidence that brain waves can influence behaviour in otherwise healthy individuals. They could also lead to the development of new drugs for medical conditions characterised by either uncontrolled or slowed movements.
Different types of brain wave have different frequencies and different locations. In this study, the researchers investigated beta waves, which have a frequency of around 20 Hertz (Hz). Earlier studies have shown that beta waves are linked to sustained muscle activity, such as that employed when holding a book. Beta activity drops just before people initiate movement.
The scientists from the Institute of Neurology at University College London injected a small electrical current via the scalp into the brains of 14 healthy people. They used an oscillating current, as this more closely resembles normal brain activity than a constant current. The level of stimulation was extremely low, and was certainly imperceptible to the participants.
The study participants were asked to use a joystick to track a small dot around a computer screen. The challenge was to keep the dot within a larger circle that jumped around the screen at regular intervals.
The research revealed that boosting the level of beta waves slowed participants' fastest performance times on the task by 10%. Given the low levels of electrical stimulation used in the tests, the results came as a surprise to the researchers.
'At last we have some direct experimental proof that brain waves influence behaviour in humans, in this case how fast a movement is performed,' said Professor Peter Brown, who led the research.
The findings also help to explain how the high levels of beta activity found in Parkinson's patients could be behind the slower movements that characterise the disease.
'If we know what patterns of brain activity slow voluntary movement, then we can try and boost these patterns in conditions like chorea and dystonia, where there is excessive and uncontrolled movement,' commented Professor Brown. 'Conversely, we can try and suppress beta activity in conditions like Parkinson's disease typified by slow movement.'
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Data Source Provider: Current Biology
Document Reference: Pogosyan, A. et al. (2009) Boosting cortical activity at beta-band frequencies slows movement in humans. Current Biology (in press). Published online 1 October. DOI: 10.1016/j.cub.2009.07.074.
Subject Index: Life Sciences; Medicine, Health; Scientific Research