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Two brain structures synchronise their activities when storing valuable information. This is the conclusion of researchers from the University of Amsterdam (UvA) and the CNRS-Collège de France.

Two brain structures synchronise their activities when storing valuable information. This synchronisation between the hippocampus and the prefrontal cortex may be caused by the chemical dopamine. This is the conclusion of researchers from the University of Amsterdam (UvA) and the CNRS-Collège de France. The results of their study have been published in the latest edition of the neuroscience journal Neuron.

The hippocampus and the prefrontal cortex are two brain structures with a major role in learning and memory. Previous studies have shown that information first enters the hippocampus and is later stored long-term in the cortex. Researchers from the UvA and the CNRS-Collège de France's Laboratory for the Physiology of Perception and Action had previously demonstrated that these two structures communicate with each other during sleep, possibly facilitating the transference of information from the hippocampus to the prefrontal cortex. This is the so-called 'memory consolidation process': incorporating new information into existing knowledge that is stored in the cortex.

Dopamine

Francesco Battaglia of the Swammerdam Institute for Life Sciences at the UvA examined, together with scientists from the CNRS-Collège de France, how our brains store only the essential parts of the constant flow of information. They taught rats a few rules in a behavioural task. By measuring the neural activity of the hippocampus and prefrontal cortex, the researchers showed that the two brain structures synchronise their activity from the time the animals understand the behavioural rules. The neurons of the two structures are then simultaneously activated and therefore their connections strengthened. A memory trace is thus formed that relates to a critical decision point of the task.

What, however, is the signal that marks important memories as such, with synchronisation and memory storage as consequence? Battaglia and his French colleagues found evidence that the synchronisation takes place after successful learning due to dopamine. This is a chemical in the brain that is involved in learning. The concentration of dopamine in the brain is enhanced when the animal receives a reward. The researchers looked at the role of dopamine in the hippocampus and prefrontal cortex. It appeared that the administration of this substance in the prefrontal cortex caused the same effect as they had observed during the learning process: the two structures synchronised their activity again. In this way, behaviour that leads to a reward is stored.

This research signigfies a relevant advance in our understanding of how different areas of the brain communicate with each other and store valuable information. It will enhance our understanding diseases involving impaired communication between brain areas, such as schizophrenia.