From New Scientist: Rats dream about the places they wish to go.

Do you dream of where you’d like to go tomorrow? It looks like rats do.

When the animals are shown a food treat at the end of a path they cannot access and then take a nap, the neurons representing that route in their brains fire as they sleep – as if they are dreaming about running down the corridor to grab the grub.

“It’s like looking at a holiday brochure for Greece the day before you go – that night you might dream about the pictures,” says Hugo Spiers of University College London.

Like people, rats store mental maps of the world in their hippocampi, two curved structures on either side of the brain. Putting electrodes into rats’ brains as they explore their environment has shown that different places are recorded and remembered by different combinations of hippocampal neurons firing together. [continue]