Chapter 5 Calcium homeostasis and learning deficits in aging

Abstract

Publisher Summary This chapter describes the intriguing roles of calcium homeostasis in learning and memory and how alterations in calcium handling in neurons may lead to deficits in learning and memory during aging. Normal brain aging is associated with physiological alterations in Ca 2+ homeostasis and deficits in learning and memory. The chapter reviews the aging-related changes in Ca 2+ homeostasis and Ca 2+ -mediated signaling cascades in hippocampal pyramidal neurons. Two hippocampus-dependent learning tasks, trace eyeblink conditioning and Morris water maze training, that are useful to examine learning and aging-related learning deficits are also discussed. The hippocampus, a structure critical for proper learning and memory functions, is frequently implicated in aging-related learning deficits. Consistent with the “Ca 2+ hypothesis of aging,” there are many reports of aging-related changes in Ca 2+ signaling cascades in hippocampal pyramidal neurons, including enhancement in the Ca 2+ -dependent afterhyperpolarization (AHP) caused by an enhanced sIAHP. The changes in protein kinase C gamma (PKCγ) in the context of aging and learning are outlined in the chapter. It is suggested that calcium dependent after hyper-polarizations are altered in a manner that reduces potentiation of synapses in neuronal circuits involved in learning and memory.