American scientists have found that defining the boundaries of individual events in memory is the hippocampus and its activity determines how well a person remembers certain events, and also changes with age. To do this, scientists conducted an experiment involving more than 500 volunteers aged 18 to 88 years. For the segmentation of the event also answered other parts of the brain, and with age the activity of some decreased and others increased. This may indicate that with age the ability to segment events and store memories simply changed rather than lost completely, write the scientists in Nature Communications.
Despite the fact that information from the outside is supplied to the person a continuous stream, in order to effectively analyze it, it should be divided into separate pieces, so it is possible, for example, to remember important and weed out what does not need to remember. Ability to the division of information is also important for the work of episodic memory: to remember a particular event, you need to clearly draw boundaries between them.
Furthermore, this ability appears to be directly associated with memory and how memories of it are organized and how they are stored. Given the fact that memory age is getting worse (primarily because of the prevalence of neurodegenerative diseases), to deteriorate should the ability to distinguish the boundaries of the events, but empirically it has not been demonstrated yet.
Fix it decided scientists under the leadership of Zacharias Riga (Zachariah Reagh) from Washington University in St. Louis: they suggested that the ability to distinguish the boundaries of events will be determined by the activity, on the one hand, the hippocampus and other related back-medium network — part of a network of passive mode of operation of the brain.
To test this, the researchers conducted an fMRI experiment involving 546 volunteers aged 18 to 88 years. All participants were shown an eight-minute excerpt from the episode “Hands up” television series “Alfred Hitchcock presents”: while they watched the movie, the scientists recorded the activity of the hippocampus and parts of the back-medium network, and then correlate the received activity with the boundaries of transition from one event to another passage.
The analysis showed that the activity of the back part of the hippocampus is very sensitive to the boundaries of the events in the film, but by age: the older people was significantly (p < 0.01) lower than in young adults and middle aged people. At the same time in front of the hippocampus such changes were not observed. In addition, the activity of the back part of the hippocampus was also significantly (p < 0.01) correlated with how well the participants recalled details about events seen after scanning.
In the rear-the average net work of the brain were also observed age dependent activity. In contrast to the hippocampus, whose activity decreased with age (which, apparently, signaled just about the deterioration of the ability to distinguish the boundaries in the events), in some parts of this network have been observed, on the contrary, a significant (p < 0.001) increase in activity with time. In particular, this was related to the frontal lobes (medial prefrontal cortex). At the same time, the activity of parietal sites, on the contrary, with age decreased.
The authors concluded that with age, the ability to define the borders of events in their analysis is not completely lost, but simply changes: she starts to answer other parts of the brain. The main role remains with the hippocampus from its activity during the delineation of the event depends on how well events are stored in episodic memory.
Redistribution of activity between other departments, in addition to the hippocampus, in turn, may have to adjust how memories are stored: additional involvement of the frontal parts of the brain, for example, can lead to the fact that memories become more General, and the number of important details forgotten.
Most often in studies of memory, participants are asked to memorize and then to repeat the sequence of objects or words. The study used the film — a little less trivial, but no less valid way to assess working memory. Other studies in which the researchers used movies, you can find out by using our test, “see What?”.