Each of the neurons is activated following a random pattern that produces what the experts call brain noise. A plausible hypothesis is that this noise may reduce the depth of the basins of attraction of the neural networks in the prefrontal cerebral cortex that are associated with the short-term memory, attention and episodic memory or personal experiences lived, providing an approach to the understanding of some of the cognitive changes that occur in people's normal aging.

The effects of neurobiological changes in aging are presented in a study published in the journal Neurology of Learning and Memory, by Gustavo Deco, ICREA researcher at the Department of Information and Communication Technologies (DTIC) and director of the Cognition and Brain Centre at UPF, together with Edmund T. Rolls, a member of the Centre for Computational Neuroscience at Oxford and of the Department of Computational Sciences at the University of Warwick in the United Kingdom.

The authors have considered the hypothesis according to which the  loss of short-term memory and the deterioration of attention that occur in the normal aging process may take place due to the increase of certain random dynamics of the brain, in conjunction with a reduction of the depth of the basins of attraction of neural networks in the prefrontal cortex. 

Something similar has been demonstrated in patients diagnosed with schizophrenia in the regulation of NMDA receptors that generate currents of dopamine in the ion channels of the synapses or neural connections. A neural attractor network model used in this study is shown in the picture on the left that corresponds to figure 1 of the paper.

In aging the activation of excitatory neurons decreases

Through computational simulations of the neurological behaviour of the brain in memory recovery and the short-term memory, the authors show in their paper that all these changes associated with the aging process reduce the activation rates of fundamentally excitatory neurons and that, at the same time, reduce the depth of the basins of attraction of neural networks, resulting in a decrease in the probability of preserving the short-term memory.

The changes that are considered in this study associated with the aging of the brain include the reduction of synaptic modification and maintenance during learning, which largely occurs in normal aging by reducing the neurotransmitters acetylcholine and dopamine, the NMDA receptors and the reduction of noradrenaline, which increases the concentration of cyclic AMP. Therefore, it reduces the excitatory-type synaptic inputs.

This approach opens up new ways of understanding cognitive aging and new perspectives for dealing with the effects of people's normal aging on the memory and cognitive functions.

Reference work:

Admund T. Rolls, Gustavo Deco (2015), " Stochastic cortical neurodynamics underlying the memory and cognitive changes in aging",  Neurobiology of Learning and Memory, 118, pp. 150-161.