Dose-Response: An International Journal: Volume 4, Issue 1
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2006-03-03
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Dose-Response, vol 4, no 1, Table of Contents
(2006-01-01)
Introduction
(2006-01-01) Diamond, David M
ON THE IMPORTANCE OF INHIBITION: CENTRAL AND PERIPHERAL MANIFESTATIONS OF NONLINEAR INHIBITORY PROCESSES IN NEURAL SYSTEMS
(2006-01-01) Thayer, Julian F
Inhibitory processes provide for the sculpting of neural action at all levels of the neuraxis. Importantly, it appears that this inhibitory function may be decidedly nonlinear in nature such that a little inhibition goes a long way in guiding the behavior of neural systems. The neural control of the heart is used as a model system to illustrate the nature of this nonlinear inhibitory control. Similar inhibitory processes function in the prefrontal cortex, in the amygdala, and between the prefrontal cortex and the amygdala in the service of organism flexibility, adaptability, and health. It is suggested that a dynamical systems perspective of neural regulation involving nonlinear inhibitory processes may be a useful framework within which to investigate the complex behavior associated with health and disease.
FACTORS THAT DETERMINE THE NON-LINEAR AMYGDALA INFLUENCE ON HIPPOCAMPUS-DEPENDENT MEMORY
(2006-01-01) Akirav, Irit; Richter-Levin, Gal
Stressful experiences are known to either improve or impair hippocampal-dependent memory tasks and synaptic plasticity. These positive and negative effects of stress on the hippocampus have been largely documented, however little is known about the mechanism involved in the twofold influence of stress on hippocampal functioning and about what factors define an enhancing or inhibitory outcome. We have recently demonstrated that activation of the basolateral amygdala can produce a biphasic effect, enhancement or inhibition, of hippocampal synaptic plasticity, depending on the timing of activation (priming or spaced activation). A key question is under which conditions do the effects of amygdala activation on hippocampus dependent memory functions change from improvement to impairment of learning and memory. In this chapter we suggest that hippocampal outcome of amygdala activation may be critically dependent on four main factors: (1) The intensity of amygdala activation, (2) the temporal relation between the activation of the amygdala and the hippocampus dependent memory function, (3) the duration of amygdala activation, and (4) the contextual input during the processing of the information.
CONCENTRATION DEPENDENT ACTIONS OF GLUCOCORTICOIDS ON NEURONAL VIABILITY AND SURVIVAL
(2006-01-01) Ábrahám, István M; Meerlo, Peter; Luiten, Paul GM
A growing body of evidence based on experimental data demonstrates that glucocorticoids (GCs) can play a potent role in the survival and death of neurons. However, these observations reflect paradoxical features of GCs, since these adrenal stress hormones are heavily involved in both neurodegenerative and neuroprotective processes. The actual level of GCs appears to have an essential impact in this bimodal action. In the present short review we aim to show the importance of concentration dependent action of GCs on neuronal cell viability and cell survival in the brain. Additionally, we will summarize the possible GC-induced cellular mechanisms at different GC concentrations providing a background for their effect on the fate of nerve cells in conditions that are a challenge to their survival.