Specificity of Functional Changes during Normal Brain Aginga

Abstract

Although there is no question that age-related alterations in neural function occur in the central nervous system (CNS) of mammals, these changes tend to be somewhat circumscribed rather than completely global, even in pathological conditions. Examples of this kind of specificity of functional neural change are drawn from experiments on the electrophysiology of the senescent rat hippocampus.

Loss of paired‐pulse facilitation at the corticostriatal synapse of the aged rat

“…An age-related loss of paired-pulse facilitation explains the in vivo observation of decreased discharge of striatal neurons in response to paired cortical activation in aged rats and cats (Cepeda et al, 1989;Levine et al, 1987). Our data and the work of others indicate, however, that aging does not produce a uniform change in the physiology of all neurons in a brain structure (Barnes et al 1991;Cepeda et al, 1989Cepeda et al, ,1992Ingram, 1988;Joseph et al, 1978;Levine et al, 1987;Morgan and Finch, 1988;Roth et al, 1984;Wallace et al, 1980). There is, on average, an age-related decline in pairedpulse facilitation, but some synapses still retain the ability to express this form of synaptic plasticity.…”

Interneurons of the hippocampus

“…They also display some limited correlation with the animal's spatial position, suggesting that they receive a disproportionally stronger excitation from "spatially" firing pyramidal cells (O'Keefe and Nadel, 1978) than from other inputs (Barnes et al 1991). These observations offer the possibility that local interactions between interneurons and principal cells may allow substantial deviation from average population behavior.…”

The Expanding Universe of Neurotrophic Factors: Therapeutic Potential in Aging and Age-Associated Disorders

“…It is well established that healthy aging is accompanied by multiple changes in many brain regions and functional decline in a number of cognitive domains [1]. Normal changes in brain physiology occur over time and can gradually result in slower information processing and alterations in memory function.…”

“…A common receptor binds all growth factors in the subfamily and a specificity receptor exists able to distinguish factors within the subfamily. In particular, GDNF family receptors (GFR) comprise a receptor complex composed by the Ret proto-oncogene product and one of the four subtypes of glycosyl phosphatidylinositol (GPI)-anchored coreceptor GFR (1)(2)(3)(4). Each GDNF family member selectively activates one of four types of GFR receptors thus leading to the activation of the Ret tyrosine kinase receptor.…”