Development of Action Potential Waveform in Hippocampal CA1 Pyramidal Neurons.

CA1 pyramidal neurons undergo intense morphological and electrophysiological changes from the second to third postnatal weeks in rats throughout a critical period associated with the emergence of exploratory behavior. Using whole cell current-clamp recordings in vitro and neurochemical methods, we studied the development of the somatic action potential (AP) waveform and some of the underlying channels in this critical period. At the third postnatal week, APs showed a more hyperpolarized threshold, higher duration and amplitude.

Role of low-voltage-activated calcium current and extracellular calcium in controlling the firing pattern of developing CA1 pyramidal neurons.

The firing pattern of individual neurons is an important element for information processing and storing. During the first weeks of development, there is a transitional period during which CA1 pyramidal neurons display burst-spiking behavior in contrast to the adult regular-firing pattern. Spike after-depolarizations (ADPs) constitute a major factor underlying burst-spiking behavior.

A novel short-term plasticity of intrinsic excitability in the hippocampal CA1 pyramidal cells.

Changes in neuronal activity often trigger compensatory mechanisms aimed at regulating network activity homeostatically. Here we have identified and characterized a novel form of compensatory short-term plasticity of membrane excitability, which develops early after the eye-opening period in rats (P16-19 days) but not before that developmental stage (P9-12 days old). Holding the membrane potential of CA1 neurons right below the firing threshold from 15 s to several minutes induced a potentiation of the repolarizing phase of the action potentials that contributed to a decrease in the firing rate of CA1 pyramidal neurons in vitro.

Intrinsic excitability is altered by hypothyroidism in the developing hippocampal CA1 pyramidal cells.

Thyroid hormone plays an essential role in brain development, so its deficiency during a critical developmental period has been associated with profound neurological deficits, including irreversible mental retardation. Despite the importance of the disorder, the cellular mechanisms underlying these deficits remain largely unexplored. The aim of this study was to examine the effects of the absence of thyroid hormone on the postnatal development of membrane excitability of CA1 hippocampal pyramidal cells.

Role of low-voltage-activated calcium current on the firing pattern alterations induced by hypothyroidism in the rat hippocampus.

Thyroid hormone deficiency during a critical period of development severely affects cognitive functions, resulting in profound mental retardation. Despite the importance of the disorder, the cellular mechanisms underlying these deficits remain largely unexplored. The aim of this study was to examine the effects of the absence of thyroid hormone on the development of the intrinsic properties of CA1 hippocampal pyramidal cells.