This beautiful micrograph shows crystals of dopamine - the chemical released when we do naturally rewarding things like eating and procreating. Dopamine also affects brain processes involved in controlling movement, mood and memory.
Spike Walker, last night’s winner of the Royal Photographic Society's Combined Royal Colleges Medal, produced this image by passing polarised light through dopamine crystals. How the crystals refract the light varies depending on their orientation within the sample, causing them to reflect light at different wavelengths. Using this technique highlights more detail in the crystal structure than regular observation through a microscope.
(Image: Spike Walker/Wellcome Images)