They succeeded in measuring the membrane potential of individual interneurones (neurones that suppress the activity of the hippocampus) in anaethetised mice. At the same time, they recorded the field potential of thousands of nerve cells in the cerebral cortex.
The researchers discovered that the interneurones they examined are active at almost the same time as the field potential of the cerebral cortex. There was just a slight delay, like an echo. This was a surprising finding, because the interneurones suppress those neurones in the hippocampus which are supposed to write information to the cerebral cortex precisely during phases of high activity. According to Mayank Mehta the result can be interpreted in very different ways. "Either the mechanism contributes to memory consolidation, or the information transfer from one part of the brain to another during sleep does not proceed as we have previously assumed." The brain researchers now want to find out which of the possible explanations applies.