CONDUCTION WITH DECREMENT: Definition and Foundational Principles Conduction with decrement is a fundamental neurophysiological process describing the rapid decomposition, or decay, of a local change in membrane potential as it propagates passively across the neuronal membrane, specifically when the initial stimulus delivered to the axon or dendrite is of a subthreshold magnitude. This phenomenon contrasts […]
Introduction to Ligand-Gated Ion Channels Ligand-gated ion channels (LGICs), often referred to as ionotropic receptors, constitute a fundamental class of transmembrane proteins crucial for rapid signaling across biological membranes, particularly within the nervous system. These channels are defined by their ability to selectively permit the passage of specific ions—such as sodium (Na+), potassium (K+), chloride […]
The Essence of the Patch-Clamp Technique The Patch-Clamp Technique stands as a foundational methodology in modern biophysics and neurophysiology, providing an unparalleled ability to record the electrical activity generated by biological membranes, often resolving the current flow through a single ion channel. This highly precise method involves the utilization of extremely fine-bore pipette microelectrodes, crafted […]
Introduction to Membrane Potential The membrane potential (Vm) is defined fundamentally as the electrical potential difference, or voltage, existing across the plasma membrane of a biological cell. This potential is a consequence of the separation of electrical charge that occurs across the thin lipid bilayer, resulting in a measurable electrical gradient between the intracellular fluid […]
Defining the Positive Afterpotential The Positive Afterpotential (PAP), also referred to in some contexts as the after-depolarization or the period following the hyperpolarizing undershoot, represents a crucial phase in the recovery cycle of an excitable cell, typically a neuron or a muscle fiber, immediately following the conclusion of an action potential spike. It is characterized […]
A reduction in the potential of a cell, usually a neuron. See action potential. Compare hyperpolarisation. DEPOLARIZATION: “Depolarisation occurs when the cell membrane in stimulated or a nerve impulse is transmitted.”
The Polarized Membrane in Neurophysiology Core Definition and Mechanisms The concept of the Polarized Membrane is foundational to biological psychology and neuroscience, describing the inherent electrical charge differential maintained across the boundary of all living cells, most critically, excitable cells like neurons and muscle fibers. Fundamentally, a membrane is considered polarized when there is an […]
Equilibrium Potential The Core Definition of Equilibrium Potential The concept of the Equilibrium Potential, often symbolized as Eion, represents the precise transmembrane voltage at which the net flow of a specific type of ion through its specialized ion channels ceases. This critical state is achieved when two powerful, opposing forces acting on the charged particle—the […]
The Resting Potential of Excitable Cells The Core Definition of Resting Potential The resting potential is defined as the imbalance of electrical charge which is present between the interior of an electrically excitable cell, such as a nerve cell or muscle fiber, and its surrounding extracellular fluid. This potential difference is maintained when the cell […]
The Action Potential Undershoot: Hyperpolarization Phase The Core Definition and Mechanism of Undershoot The undershoot, also known as the after-hyperpolarization phase, is a critical component of the Action Potential (AP) cycle in excitable cells, particularly neurons and muscle fibers. It is defined as the transient period during which the membrane potential (MP) temporarily drops below […]
Excitatory Threshold: The Gateway to Neuronal Communication The Core Definition of Excitatory Threshold The excitatory threshold is a fundamental concept in neuroscience, representing the critical level of membrane potential that a neuron must reach at its axon hillock in order to generate an action potential. This threshold acts as a crucial physiological switch, determining whether […]
Endosomotic Current: Revisiting an Unresolved Phenomenon Endosomotic current (EC) is a phenomenon that remains poorly understood and largely unresolved in the scientific literature. EC is an electrical current that is generated by endosomal membranes and is thought to play a role in cell homeostasis, ion transport, and membrane potential maintenance. Despite its potential importance, the […]