First images showing how pressure intensifies our thoughts

The UCL academics have spent the past two years designing a miniature high-pressure cell that can sit beneath a microscope used for optical imaging of thought patterns in the brain. The cell has enabled the team to obtain the first images showing that electrochemical signals are intensified and spread further along certain brain pathways at high pressure. The images provide the first clues as to why animals can be excitable under high pressure conditions.

The researchers coated the surface of brain slices with a dye that is sensitive to sub-millisecond changes in voltage. The researchers then immersed the samples in artificial cerebrospinal fluid and increased the pressure to up to 40 times standard air pressure before sending voltages through the brain.

The team will now use the microscope system, which is installed in Professor Greenfield's Oxford laboratory, will now be used to examine what is happening in the brain when the anaesthetic effects of drugs like alcohol are reversed at high pressure. The results will provide important new insights into the behaviour of anaesthetics: although they are widely used in medicine, no one knows exactly how they work.

By filling the chamber with a range of inert gases, the researchers also hope to shed light on the euphoria experienced by mineworkers and deep-sea divers due to nitrogen narcosis - a phenomenon that diver Jacques Cousteau called "the drunkenness of the deep". This appears to be related to the unexpected anaesthetic effects caused by xenon, normally known as a chemically inert gas, and is distinct from decompression sickness or 'the bends'.

"Over two centuries of systematic chemical research, most of our chemical knowledge has been gained from studies carried out near standard air pressure, while much of the matter in the universe exists under much higher pressure conditions," says Professor McMillan.

Researchers around the world are starting to use high-pressure techniques adapted from physics and geology to study chemical behaviour under conditions like those deep inside the planets. However, there has been little work to date on higher biological functions, like neuroscience - the collaboration developed between the UCL physical scientists and Professor Greenfield, a neurophysiologist, is unusual.

"By linking high-pressure science and neurobiology, we are pushing the boat out very far, but we hope to discover new scientific territory that we will explore using our new techniques," said Professor McMillan.

For more information use the links at the bottom of this article.

Image 1: Professor Paul McMillan

Image 2: Dr Agnieszka Wlodarcyk

Image 3: The high-pressure cell

• Links:
• Professor Paul McMillan
• Professor Susan Greenfield