Memorising and reminiscing makes your brain work faster

Pedagogues and psychologists involved in education are striving to make training more efficient. To achieve this, it would be useful to understand what happens in a trainee’s brain during learning. Only neurophysiologists can sort that out, however, not everything is clear to them yet.

Thus, it can be expected that memorizsation and reminiscence processes (which make the essence of training) should be reflected in changes of the brain’s electrical activity nature. It means that these changes may be recorded with the help of the most traditional brain investigation method – Electroencephalogram (EEG).

The research carried out by physiologists of the Institute of the Human Brain (Russian Academy of Sciences) in St. Petersburg and the Institute of Cognitive Neurology (Modern Academy of Humanities) in Moscow involved 57 persons under investigation – students of the Modern Academy of Humanities aged 17 to 20. They were to learn seven pairs of words – in Russian and in Latin which was previously unknown to them. Each pair of words was presented on the monitor screen for 5 seconds. The students were tested in a minute and a half – Russian words were shown to them and they had to recollect the Latin equivalent. Experimenters recorded students’ EEG through 19 electrodes laid on the head skin in three states: at rest, while memorising information and when extracting the information from memory.

Having analysed the findings, the researchers singled out several frequency ranges where the brain operates. These are the theta (4 to 7 Hz), alpha-1 (7 to 10 Hz), alpha-2 (10 to 13 Hz), beta-1 (13 to 18 Hz), beta-2 (18 to 30 Hz) and gamma (30 to 40 Hz) ranges. In three different states, the researchers compared the brain’s electric activity power in all of these ranges. It has turned out that in the course of word memorising and recollection, the alpha-range power decreases on the greater part of the cortex surface. The alpha rhythm is most distinctly expressed when a person is in a calm wakeful state, but any mental load results in its depression.

The reverse situation is observed as regards to fast rhythms of the brain. When the students fulfill a task, power increases in the beta-2 range and particularly in the gamma range (which is the highest frequency range), this happening across the entire cerebral cortex surface. Physiologists believe this is non-random. They assume that fast cerebral activity correlates with active memory use.

The EEG power increases particularly in quick ranges, just as the alpha-rhythm power decreases – when information is extracted from memory. It can be assumed that this process is more “power-consuming” than that of memorisation.

Under the same conditions, the researchers analysed another EEG parameter – spatial synchronisation, which shows to what extent various areas of cerebral cortex work synchronously at rest and at mental load. The main result is as follows – synchronisation increases in all frequency ranges if memory is actively used. That means that in the course of task solution different areas of cerebral cortex start working in coordination, and the entire brain works as a single whole. Bonds occur not only between different areas of the cortex in one hemisphere, but interhemispheric bonds are also formed. The process is most evident when information is being extracted from memory.

So, the researchers have obtained trustworthy correlations between active memory state and the EEG characteristics. However, there is still a question the researchers cannot yet answer unambiguously. To what extent the phenomena observed – increase of fast frequencies’ power and spatial synchronisation – are really connected with memory mechanisms, and to what extent they simply reflect the brain transition to more active state? The reply is to be provided by future investigations.