title: Stochastic cortical neurodynamics underlying the memory and cognitive changes in aging.
abstract: The relatively random spiking times of individual neurons provide a source of noise in the brain. We show how this noise interacting with altered depth in the basins of attraction of networks involved in short-term memory, attention, and episodic memory provide an approach to understanding some of the cognitive changes in normal aging. The effects of the neurobiological changes in aging that are considered include reduced synaptic modification and maintenance during learning produced in part through reduced acetylcholine in normal aging, reduced dopamine which reduces NMDA-receptor mediated effects, reduced noradrenaline which increases cAMP and thus shunts excitatory synaptic inputs, and the effects of a reduction in acetylcholine in increasing spike frequency adaptation. Using integrate-and-fire simulations of an attractor network implementing memory recall and short-term memory, it is shown that all these changes associated with aging reduce the firing rates of the excitatory neurons, which in turn reduce the depth of the basins of attraction, resulting in a much decreased probability in maintaining in short-term memory what has been recalled from the attractor network. This stochastic dynamics approach opens up new ways to understand and potentially treat the effects of normal aging on memory and cognitive functions.
authors.affiliation: Oxford Centre for Computational Neuroscience, Oxford, UK; University of Warwick, Department of Computer Science, Coventry CV4 7AL, UK. Electronic address: Edmund.Rolls@oxcns.org.
authors.forename: Edmund T
authors.initials: ET
authors.lastname: Rolls
authors.affiliation: Universitat Pompeu Fabra, Theoretical and Computational Neuroscience, Roc Boronat 138, 08018 Barcelona, Spain; Institucio Catalana de Recerca i Estudis Avancats (ICREA), Spain.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Deco
mesh_terms: D000109:Acetylcholine / Q000502:physiology; D000200:Action Potentials; D000375:Aging; D002540:Cerebral Cortex / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004298:Dopamine / Q000502:physiology; D006801:Humans; D008568:Memory / Q000502:physiology*; D008959:Models, Neurological; D016571:Neural Networks, Computer; D009474:Neurons / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013269:Stochastic Processes; D013569:Synapses / Q000502:physiology
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; D000109:Acetylcholine; D004298:Dopamine; D009638:Norepinephrine
keywords: Acetylcholine; Aging; Cortical attractor networks; Memory; NMDA receptors