Neurons

Neurons

Neuroscience is the study of the nervous system, or the CNS – central nervous system and PNS – peripheral nervous system. The CNS contains the brain and the spinal cord, while the PNS represents cranial nerves and ganglia. Neurons are brain cells. Several different types of neural and glial cells exist: oligodendrocytes, astrocytes, pyramidal cells, stellate spiny neurons, Schwann cells.

A neuron consists of a nucleus, the cell body or soma, an axon and dendrites ending in terminal buttons. Neurotransmitters are discharged into the synaptic cleft, the space between neurons. The are several billions neurons in the brain, some comparing the number to the amount of stars in the Milky Way galaxy.

Brain stimulation. An artist’s impression of stained neurons. As can be seen from the picture, image: Public Domain

Loud noise or sound can cause hair cell trauma and, consequently, noise-induced hearing loss (NIHL). Fryatt et al. (2011) explain that this is often due to damage to spiral ganglions, the afferent neurons innervating the cochlear neuronal components. Other apoptosis is due to chemical and other trauma, potentially resulting in other auditory conditions such as tinnitus and hyperacusis.

Neuron can also refer to the neural simulation software, used by neuroscientists in research, such as Varela and colleagues (2011) in their study on PFC (prefrontal cortex) neurons, stress and plasticity. Many models of neuroplasticity have been proposed (Brito & Gerstner, 2011), such as the concepts: ICA (independent component plasticity), STDP (spike timing dependent plasticity), and non-linear Hebbian rule as related to BCM theory.

References:

• Brito, C. SN & Gerstner, W. (2011). General conditions for spiking neurons and plasticity rules to perform independent component analysis. BMC Neuroscience, 12 (1): 124.
• Fryatt, A. G., Mulheran, M., Egerton, J., Gunthorpe, M. J. & Grubb, B. D. (2011). Ototrauma induces sodium channel plasticity in auditory afferent neurons. Molecular and Cellular Neuroscience, 48 (1): 51-61.
• Varela, J. A., Wang, J., Varnell, A. L. & Cooper, D. C. (2011). Control over stress induces plasticity of individual prefrontal cortical neurons: A conductance-based neural simulation. Nature Proceedings: Neuroscience, 1-2.

Copyright © 2011 Megan Jorgensen. All rights reserved.