Light as a Life Tool
Visual light, and radiation of other frequencies, are highly important for scientific research. The first light microscopes made it possible for the first time to see that organisms from plants to humans are composed of cells. Electron microscopes have allowed scientists to study the structural components of cells in great detail, and even determine the shapes of individual proteins. Many lifeforms also use light to attract a mate or prey, or deter an attacker. Following the identification of the gene coding for the fluorescent protein that makes certain jellyfish glow green it has become possible to use this to genetically label proteins in a living cell, or even a live animal. This means that now the location of proteins in a cell can be determined exactly. A major recent step forward in neuroscience came with the discovery of protein channels in algae that conduct ions in response to light. By creating transgenic mice that have these proteins in their brain neurons, it is now possible to modulate the activity of these neurons by shining light into the brain though microscopic fibre optic cables. This new science of optogenetics allows neurons to be switched on or off experimentally. The optogenetic approach has been used to uncover the neural circuits involved in memory, pain and pleasure. In the future this technique might be used to treat physical pain or depression in people. Controversially, it might be also be misused, to supress memories, or even create completely false ones in people’s heads.