The discovery of X-rays made it possible to study mental disorders and neurological diseases through photographic material. Later on, the brain literally became visible in CT scans and MRI scans, which were also used to locate the function of the different brain areas.

The X-ray was discovered by Wilhelm Röntgen (1845-1923) in 1895. It immediately attracted the attention of psychiatrists and neurologists. Since they were always on the lookout for insights into the physical operation and failure of the brain but had previously been limited to dissections after the patients had died, they immediately saw the potential of the X-ray for their field. It was now possible to research and study mental disorders and neurological diseases using photographic material.

Gradually, it was now possible to literally map out an image of the brain. In 1927 Egas Moniz (1874-1955) injected iodine into the circulation of the brain, which allowed it to be viewed in greater detail. Building on its knowledge of sonars and radars, the field of echography succeeded in mapping out high-frequency sound vibrations after World War II. This was another step forward, as this technology delivered better images of soft tissue than radiology. The next introduction to examination rooms was the CT scanner, which measures the absorption of X-rays. After that came the MRI scanner, which uses magnetic resonance imaging to create three-dimensional images of the nervous system. To a certain extent, MRI scanners can even be used to assess the functions of the various areas of the brain. In addition, this kind of function localization – which is somewhat similar to Gall's work – was made possible largely due to progress in nuclear science. As a result, areas of the brain can be linked to specific abilities such as the sensation of pain or moral decision-making.