Lectures3+4-Chapter_2-BiologicalFoundations

Brain function at the cellular level all complex

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Unformatted text preview: ed in this way. Brain Function at the Cellular Level All complex aspects of human behavior are the result of interaction among an intricately connected network of neurons. All neurons have the same basic structure Four basic parts of a neuron Electrical signals only flow from dendrites to soma to axon. Axon ends in a set of terminals at its contact sites with other neurons; these terminals release neurotransmitter onto dendrites of other neurons 33 34 Components of neurons Cell body or soma contains cell nucleus and keeps the cell functional. Dendrites are the many branches projecting out from the soma that receive inputs from other neurons and transmit that information electrically to the soma. Axon carries information away from the soma to other neurons. Terminals are end points of the axons that communicate with other neurons. 35 The Neuron Doctrine Camillo Golgi (1843-1926) The proof that the brain was made up of discrete nerve cells (the ‘neuron doctrine’) as opposed to a moreor-less continuous network of fibers electrically coupled to each other (‘reticular’ theory) came from Ramon y Cajal’s use of a staining technique invented by Golgi (who ironically believed in a reticular theory) Santiago Ramon y Cajal (1852-1934) 36 Cajal’s “Laws” Law of dynamic polarization: Information in a neuron always flows in a predictable direction. [While the generalization is usually true, there are chemical signaling mechanisms between neurons that violate it, where information can flow either “backward” or non-directionally]. Law of connectional specificity: No physical continuity exists between one neuron and the next. [There are classes of neurons that are electrically coupled to each other via specialized cell structures that do make them physically continuous]. Each neuron is a separate entity. Connections between neurons occur at specialized contact points in a very precise manner. 37 Neuronal Diversity Neurons are highly diverse in terms of size, shape, and Example of a bipolar structure, yet neuron (has 1 they all dendrite) have a soma, a set of dendrites, and a single axon (which can branch afte...
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This document was uploaded on 02/16/2014.

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