Rhythmic Activities of Neurons Necessary For Learning

The hippocampus is that integral part of brain structure that facilitates learning. Scientists of Munich based Max Planck Institute of Psychiatry have discovered that through its unique control mechanism, inputs and outputs neuronal electrical signals could be processed (filtered or allowed) accordingly for the purpose of regulating the processes of memory and learning.

As what might have been expected, effective transmission of signal is only possible with the alleged theta-frequency impulses of cerebral cortex. When frequency falls within range of 3-8 hz, these impulses are capable of generating electrical waves that subsequently travel through hippocampus. On the other hand, frequency outside the specified range would invoke no transmission, or surge only weaker transmission. In addition, when it comes to learning or knowledge retention, a process known as LTP or long-term potentiation, such activity waves need to happen for a prolonged duration. Armed with this knowledge, scientists are now able to better explain why humans are more mentally alert after the coffee or happen to get caught in a situation of acute stress. The theory and experiments suggest that both caffeine corticosterone (stress hormone) help to boost the flow of activity.

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You may wonder why some educators insist on rote learning during our formative years. But really there is a scientific basis behind the approach. This can be demonstrated in electrophysiological experiments conducted among mice. Scientists from Research Group of Matthias Eder have been able to capture and measure electrical impulses that are transmitted between neurons in hippocampus of mouse. With the help of fluorescence microscope, observations were made on how the neurons forwarded signals in real time.

Through a simulation on hippocampus' input region, Jens Stepan, junior scientist, Max Planck Institute of Psychiatry, Munich, was able to conclude that in particular the theta-frequency stimulations lead to effective transmission of impulse across hippocampal CA3/CA1 region. The finding represents a significant milestone in brain study as it was previously known that theta-rhythmical neuronal activities in entorhinal cortex are at their busiest when any new information are fed into the subject in a focused way. Another important aspect of this research is that it demonstrates that hippocampus can be highly selective with regards to entorhinal signals to be processed. For some reason, it is able to discern important and, by deduction, potentially good-to-remember information from unimportant one and correspondingly incorporate it into a physiologically specific way.

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One other aspect of the discovery is related to the alleged long-term potentiation (LTP) of transmission of signal at CA3-CA1 junctions, which we know is essential for memory and learning. Through this study, we have known that the CA1-LTP activity take place only when signals/waves flow through hippocampus for a decent period of time. In laymen speaks of human learning behavior, if we were to embed an image or activity into memory, what we should do is to intently view the image. As we train the eyes on the object for some time, activity waves produced would create distinguished image of the object in our brain.

If nothing else, this work by Matthias and his learned colleagues is successful in sealing off the knowledge gap. "Our investigation on neuronal communication via the hippocampal trisynaptic circuit provides us with a new understanding of learning in the living organism. We are the first to show that long-term potentiation depends on the frequency and persistency of incoming sensory signals in the hippocampus," says Matthias Eder.