The human brain is an incredible thing, enabling us to recall past events in great detail. But sometimes people only remember parts of an experience, while they can perfectly recall all the details of a different event. Now researchers at the University of California may have found a clue as to why this is. The team have been using a technique called functional MRI scanning to look at how different regions of the brain are used during certain tasks, such as remembering things. This type of brain scans allows scientists to spot regions of activity in the brain, in real time. The scientists tested 23 people by giving them a list of words while they were in the scanning machine. The words were in different colours, and appeared in different area on a computer screen. Then later on, the people were shown the words again, mixed with new words, and asked which ones they remembered, and if they could recall what colour and where the words were. The team found that if people remembered what colour the words were, then the part of their brain associated with colour recognition had been active when they first saw the words. A similar thing happened with the location of the word on the screen - people could remember it if the spatial awareness bit of their brain was active when they were learning the word. But the team found that if people remembered the word, the colour and the location, then an extra bit of their brain had been active when they were learning. This region is known as the intra-parietal sulcus, and it looks like it's responsible for linking together all the aspects of the memory. The results suggest that in order to remember all the details about something, this extra brain region has to be active to bind all the memories together. In fact, people who have brain damage in this region find it hard to remember different aspects of things. The lead researcher, Michael Rugg, says the results mean that you can't get out of memory what you don't put into it. Basically, this means it's not possible to recall things later on if you don't remember them in the right way at the time. But unfortunately the team don't have any good suggestions as to how to improve your memory.