Image of the memory

2001/12/03 Elhuyar Zientzia

• Anatomia/Fisiologia

Scientists at the University of California have taken for the first time images of the structural changes suffered by neurons by keeping memory short and long lasting.

Neurologists have long been investigating the permanent and temporary connections that occur between neurons by stimuli. Now in the magazine Cell Michael A. Thanks to the work published by Colicos and his team-mates, neuronal activity has been shown. In fact, although memory was suspected that in the brain there were connections between neurons, so far it could not be seen. Although some researchers said that the number of synapses increased, others did not notice any changes in the brain.

To solve the problem, the California team focused on a few hippocampus neurons. In fact, in the hippocampus several types of basic memories are formed for the human being. For this reason, they filmed how the new connections were created when responding to the electric impulse.

To do this, they have had to employ new techniques and models that allow to visualize actina with fluorescence and, on the other hand, stimulate neurons as happens in the brain. Until now this stimulation was performed by electrodes. But the electrodes damaged and killed neurons. The new technique based on the photoconductive characteristic of silicon allows neurons not to lose their physiological functioning.

Thus, when the model stimulated neurons once, they saw that intracellular actin was activated and moved towards the neurons that were connected. In addition, the activity of the first neuron affected those around it and its actin was moving towards that first neuron. These changes were temporary, lasting between 3 and 5 minutes and disappeared 10 minutes. On the other hand, if in an hour it was estimated 4 times, the changes were permanent and were kept for life.

It seems that the same thing happens in the human brain: when something is seen or heard once, it keeps a few minutes. But what is seen or heard over and over again at the same time, forever remains in memory.