Subthreshold membrane potential oscillations
Encyclopedia
Subthreshold membrane potential oscillations are rhythmic fluctuations of the voltage difference between the interior and exterior of a neuron
, in the nervous system
.
Neurons produce action potentials when their membrane potential
increases past a critical threshold. If the voltage is below the threshold the neuron does not fire, but the membrane potential still fluctuates due to postsynaptic potentials
and intrinsic electrical properties of neurons. In some type of neurons, the membrane potential can oscillate
at specific frequencies. Although subthreshold oscillations do not directly result in neuronal firing, they may facilitate synchronous activity of neighboring neurons. It may also facilitate computation, particularly processing of sensory signals
and action potentials, rhythmic subthreshold membrane potential
oscillations (a particular type of neural oscillations
). These oscillations, which resembled sinusoidal wave forms were originally discovered in the mammalian inferior olive nucleus cells. The functional relevance of subthreshold oscillations concerns the nature of the intrinsic electrical properties of neurons, that is, the electrical responsiveness not derived from interactions with other cells. These properties define the dynamic phenotype
independently from form or connectivity. Subthreshold oscillation
frequency can vary, from few Hz to over 40Hz and their dynamic properties have been studied in detail in relation to neuronal activity coherence
and timing in CNS, in particular with respect to the 10Hz physiological tremor that controls motor execution, Theta rhythm
in the entorhinal cortex and gamma band activity in cortical inhibitory interneurons and in thalamus
neurons. They have also been described and studied in layers V of the entorhinal cortex, the inferior olive in vivo, the olfactory bulb
and the dorsal cochlear nucleus. The dynamic aspects of such oscillations have been defined using mathematical modeling.
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
, in the nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
.
Neurons produce action potentials when their membrane potential
Membrane potential
Membrane potential is the difference in electrical potential between the interior and exterior of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid bilayer with a variety of types of proteins embedded in it...
increases past a critical threshold. If the voltage is below the threshold the neuron does not fire, but the membrane potential still fluctuates due to postsynaptic potentials
Postsynaptic potential
Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse. Postsynaptic potentials are graded potentials, and should not be confused with action potentials although their function is to initiate or inhibit action potentials...
and intrinsic electrical properties of neurons. In some type of neurons, the membrane potential can oscillate
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
at specific frequencies. Although subthreshold oscillations do not directly result in neuronal firing, they may facilitate synchronous activity of neighboring neurons. It may also facilitate computation, particularly processing of sensory signals
Overview
Neurons display, beyond synapticSynapse
In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell...
and action potentials, rhythmic subthreshold membrane potential
Membrane potential
Membrane potential is the difference in electrical potential between the interior and exterior of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid bilayer with a variety of types of proteins embedded in it...
oscillations (a particular type of neural oscillations
Neural oscillations
Neural oscillation is rhythmic or repetitive neural activity in the central nervous system. Neural tissue can generate oscillatory activity in many ways, driven either by mechanisms localized within individual neurons or by interactions between neurons...
). These oscillations, which resembled sinusoidal wave forms were originally discovered in the mammalian inferior olive nucleus cells. The functional relevance of subthreshold oscillations concerns the nature of the intrinsic electrical properties of neurons, that is, the electrical responsiveness not derived from interactions with other cells. These properties define the dynamic phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
independently from form or connectivity. Subthreshold oscillation
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
frequency can vary, from few Hz to over 40Hz and their dynamic properties have been studied in detail in relation to neuronal activity coherence
Coherence (physics)
In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....
and timing in CNS, in particular with respect to the 10Hz physiological tremor that controls motor execution, Theta rhythm
Theta rhythm
A theta rhythm is an oscillatory pattern in EEG signals recorded either from inside the brain or from electrodes glued to the scalp. Two types of theta rhythm have been described...
in the entorhinal cortex and gamma band activity in cortical inhibitory interneurons and in thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
neurons. They have also been described and studied in layers V of the entorhinal cortex, the inferior olive in vivo, the olfactory bulb
Olfactory bulb
The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...
and the dorsal cochlear nucleus. The dynamic aspects of such oscillations have been defined using mathematical modeling.