Initiation And Propagation In Cerebellar Purkinje Neurons Case Study

Normally in a muscle cell or a neuron, the voltage-gated sodium channels are supposed to open and close. Primarily, when the ligand-gated sodium channels open, sodium ions flood into the cell. Since sodium ions have a positive charge, this causes the cell interior to become more positive, a term known as depolarization; as a result, voltage-gated sodium channels open, causing even more sodium ions to enter the cell. Meanwhile, the action potential continues to move down the cell, and voltage-gated potassium channels open to allow potassium ions out of the cell to escape the positive interior; this process, known

The central nervous system (CNS) comprises grey matter, which contains neuron cell bodies and white matter, which contains the nerve axons. Most of the nerve axons are concentrically wrapped around by lipid-rich biological membrane, known as the myelin sheath. In the CNS, myelin is produced by oligodendrocyte. a type of glial cell. (Pfeiffer et al., 1993). These electrical insulating, multilamellar membranes significantly increase the electrical resistance, in which to prevent leakage of electrical currents from the axons, as well as decrease electrical capacitance to reduce the ability of the axons to store electrical energy (Shivane &

As well as these there are also the axon of the cell which is covered in myelin sheaths which carried information away from the cell body and hands the action potentials, these are small short bursts of change in the electrical charge of the axon membrane through openings of ion channels, off to the following neurons dendrites through terminal buttons at the end of the axons. Whenever an action potential is passed through these terminal buttons it releases a chemicals that pass on the action potential on to the next neuron through the terminal button and dendrite connection. The chemicals that are

* Interneurons or Pseudopolare (Spelling) cells form all the neural wiring within the CNS. These have two axons (instead of an axon and a dendrite). One axon communicates with the spinal cord; one with either the skin or muscle. These neurons have two processes. (Examples are dorsal root ganglia cells.)

_There are less leakage channels for Na+ compared to K+_that’s why it didn’t alter the membrane potential in the resting neuron._

Several studies have exhibited reductions in neuronal number in developing animals following alcohol exposure. However, neuronal death is a consequence of normal development. Some neuronal populations maintain a fifty percent reduction in the number before stabilizing in an adult configuration. The possibility exists that developmental alcohol exposure may in at least some circumstances, be accelerating the deaths of only those neurons that

The most frequent inflammatory disease of the central nervous system (CNS) impacts the lives of two and half million people in the world, Multiple Sclerosis (MS) (Schattling, 2013). Growing up, this disease has personally affected my family, and seeing a first hand account of the burden and turmoil that this disease causes for all of its patients it is critical to understand how this disease degenerates neurons and axons. The key players in this process are nervous system ion channels that regulate the influx and efflux of sodium and calcium, whether through exchangers or voltage-gated channels. There are normal molecular settings in neurons and there are MS molecular settings; the two are very different and progressively become further

Finally, the advent of electron microscopy allowed us to visualise anatomical details at the nano scale. It confirmed the synaptic gap that Sherrington theorised exists, provided incontrovertible validation of the neuron theory, and became a crucial element in many neuroanatomical research that followed (Shepherd, 1991). From these developments, it is hard to deny that the understanding of the anatomy of the neuron and its

The nervous system functions by using a combination of chemical and electrical processes to control voluntary (somatic) and involuntary (autonomic) movement. This is achieved through the transmission of signals via specialised cells called neurones and nerves, as shown in Figure 1 (livescience, 2016). In the brain, ion channels exist that allow a steady current to pass through by firing regularly. In the event of a seizure, ion channels that have been genetically damaged

An action potential is a short electrical impulse generated at the axon hillock which travels the length of an axon. Its generation happens in three distinct stages, depolarisation, repolarisation and hyperpolarisation. When the threshold of excitation is reached, depolarisation starts, the threshold is between -55mV and -65mV in most neurons. When the neuron is stimulated voltage-activated Sodium (Na+) channels open, allowing Na+ ions to rush into the neuron. This reverses the polarity in the neuron towards its peak of +40mV. At this peak Na+ channels

Like the cerebral cortex, it is roughly divided into two hemispheres that are connected at the midline by the vermis, which is responsible for interhemispheric communication and interaction with the surrounding cerebrum and brain stem. The cerebellum is composed primarily of specialized neurons called Purkinje cells, granule cells, and astroglia. These cells are organized so that the exterior of the cerebellum is primarily composed of gray matter surrounding a core (cerebellar nuclei) of white matter. Ethanol-induced abnormalities in the cerebellum manifest as an overall reduction in volume, with certain areas more affected by ethanol’s toxicity than others. The affected areas include the anterior region of the vermis and the cerebellar nuclei, the abnormalities of which are highly dependent on the developmental timeframe of prenatal

This was determined through a set of experiments. To determine if sodium channel clustering depended on glial cells, hippocampal cells were cultured in the absence of glial cells. This experiment showed that, in the absence of glial cells, Na+ channels were found along the entire length of the axon. They were not concentrated in clusters. Then, another experiment was conducted to determine if the node of Ranvier formation was contact dependent. In this experiment, the dorsal root ganglia were bathed in the extracellular fluid of Schwann cells. Again, nodes of Ranvier did not form. This showed that the node of Ranvier formation mechanism was contact dependent. Another experiment was done to determine if node of Ranvier formation depended on molecular signaling between the Schwann cells and the axon. In this experiment, Schwann cells on a myelinated axon were killed. The nodes of Ranvier disappeared. This showed that molecular signaling played a role in node of Ranvier formation. Eventually, an experiment found that ankyrin G was concentrated at nodes of Ranvier. To determine what proteins interacted with

Within the hippocampus, long-term potentiation (LTP) results due to the increased activity between a presynaptic and a postsynaptic neuron. The stimulation and subsequent depolarisation of a presynaptic CA3 pyramidal neuron results in the opening of voltage-gated calcium channels (VGCC). Thus, an influx in Ca2+ occurs, and glutamate vesicles are fused via synaptotagmin. The fusing of these vesicles allows the release of glutamate, a neurotransmitter which will bind to AMPA receptors and induce the influx of Na+ into the postsynaptic CA1 pyramidal neuron. This will result in the depolarisation of the postsynaptic neuron, which is one of the requirements for the opening and consequent induction of Ca2+ through the NMDA receptor. Through a cascade

The extracellular Na+ did not alter the membrane potential in the resting neuron because the Na+ channels were mostly closed.

Nerve cells generate electrical signals to transmit information. Neurons are not necessarily intrinsically great electrical conductors, however, they have evolved specialized mechanisms for propagating signals based on the flow of ions across their membranes.