Thanks to complex computer algorithms, it is possible to simulate a virtual network in which a large number of neurons interact. These models can simulate the functioning of the structures in our brains. According to the computer model published in PNAS, when the working memory needs to be increased, the prefrontal cortex reinforces the activation of the parietal cortex, in which the information is temporarily stored. A brief stimulus that reaches the parietal cortex generates a reverberating activation that maintains a subpopulation active, while inhibitory interactions with neurons further away (lateral inhibition) prevents activation of the entire network. This lateral inhibition is also responsible for limiting the mnemonic capacity of the parietal network. The reinforcement of the parietal cortex by the prefrontal cortex prevents its inhibition, thereby temporarily improving working memory.
To verify this hypothesis, 25 healthy individuals carried out simple visual-memory tests while inside a functional magnetic resonance scanner. The differences in their ability to complete the exercises were linked to the intensity of activation of the prefrontal cortex and to their interconnection with the parietal cortex. The IDIBAPS and Karolinska researchers thus confirmed the hypothesis formulated based on the computer model. The more the prefrontal cortex is activated, the greater the capacity of the parietal cortex for retaining short-term visual information - an indicator of working-memory capacity.
This study explains many diverse results that have been obtained in recent years in psychology and neuroimaging studies on working memory. This is an innovative view of the neurobiological mechanisms of cognitive control and opens up new lines of research. Clinical studies will be needed to determine whether the stimulus of the prefrontal cortex, or its training by means of memory exercises and games, can have an effect on diseases in which working memory is damaged, such as depression or schizophrenia.