Overloading the working memory in a person disrupts synchronization between the three parts of the brain


    Cortical architecture in accordance with the canonical model of neural microcontour in the cerebral cortex of the primate. Four types of neurons (stellate neurons, superficial and deep pyramidal neurons and inhibitory interneurons) are connected by exciting (red) and inhibitory (black) compounds. Such a set of neurons and connections is motivated by anatomical and theoretical considerations in favor of the canonical model.

    A person is able to simultaneously hold a limited number of objects in working memory . The amount of working memory is directly related to cognitive ability., which decreases with neurological diseases and mental disorders. Scientists have been studying for several decades how the loading of working memory affects the processing of neural signals in the brain. They are trying to understand why working memory is so small. And why do cognitive abilities fall sharply if you load working memory beyond what is supposed to be.

    Studies of the working memory load and its limitations focused on coordinating activities in the frontoparietal network. It is known that it plays an important role in working memory . These studies predicted the limits of the working memory bandwidth by measuring the level of network integration (that is, how the different parts of the frontoparietal network are connected together) and the timing of these partson the activity of brain waves in the gamma range . Recent studies have shown that visual working memory works independently for two visual hemifields - left (LFP) and right (RFP), and that load changes have different effects on the vibrational dynamics of different frequencies .

    Researchers at the Pickauer Institute for Learning and Memory at the Massachusetts Institute of Technology have come close to explaining why cognitive abilities decrease when working memory is overloaded. They found that in this case, the pairing is broken, that is, the synchronization of brain waves of three key regions.

    Scientists have developed a large-scale theoretical model of the cortical network, which consists of the prefrontal cortex (PFC), the eye fields of the frontal cortex (FEF) and the lateral intra parity area (LIP). This is an extended version of the previous model based on predictive coding, but only here are used Cross Spectral Density (CSD) responses to determine the changes in neural connections that underlie changes in spectral power at different frequencies.


    Large-scale canonical neural microcontrol

    model The new model allowed us to determine how load-dependent effects affect functional connectivity with sharp changes in neural connectivity when the working memory capacity is exceeded and the prediction signals are destroyed.

    “When you reach the maximum capacity [working memory], the feedback loop is lost,” explainsProfessor Earl Miller, co-author of research. This loss of synchronization means that the three regions (PFC, FEF, and LIP) can no longer interact with each other to maintain working memory: the prefrontal cortex of PFC stops giving feedback to FEF and LIP. After a certain level of brain load, the low-frequency signals between PFC, FEF and LIP are out of sync - and the working memory no longer functions.

    The experiment confirmed the previous discovery that the amount of working memory is independent for the left and right half-fields .

    The average number of objects that can be held in visual working memory varies among different people, but usually amounts to four objects, the professor says. The volume of a person’s working memory is usually associated with the level of intelligence.

    Having made a number of scientific discoveries on the functioning of the brain and working memory of a person, the study authors Earl Miller and Timothy Bushman founded the commercial company SplitSage , which develops programs to test the intellectual abilities of a person and the volume of his working memory. In the future, such programs may enter the standard test suite for knowledge workers.

    The scientific article was published on March 28, 2018 in the journal Cerebral Cortex (doi: 10.1093 / cercor / bhy065).

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