Neural & Synaptic Transmission
The nervous system is made up of neurons and glila cells. Neurons are the basic communication links in the nervous system. Glila cell provide support for neurons and contribute to communication. Neurons normally transmit a neural impulse (an electric current) along an axon to a synapse with another neuron. The neural impulse is a brief change in neuron’s electrical charge that moves along an axon. It is an all-or-none event. Action potential triggers the release of chemicals called neurotransmitters that diffuse across the synapse to communicate with other neurons. Transmitters bind with receptors in the postsynaptic cell membrane, causing excitatory or inhibitory PSPs. Most neurons are linked in neural pathway, circuits, and networks. In the nervous system, the neural impulse functions as a signal. For that signal to have any meaning for the system as a whole, it must be transmitted from the neuron to other cell. As noted above, this transmission takes place at special junction called Synapses, which depend on chemical messengers. To explain in another way neural impulses are electro chemical events. When Neurons stimulated beyond threshold level, there is a rapid shift in its polarity from negative to positive charge. This reversal of charge, called an action potential or neural impulse, is generated along the length of the axon to the terminal buttons. When neural impulse reaches the terminal button, it triggers the release of neurotransmitters, the chemical messengers that carry the message across the synapse to neighboring neurons. Neurotransmitters can have either excitatory or inhibitory effect to the neurons at which they dock. Example: The educational and childcare reformers who have used brain science as the base for their campaigns have primarily cited to key findings: the discovery of critical period in neural development and the demonstration that rats raised in “enriched environments” have more synapses than rates raised in “impoverished environments.” A critical period is a limited time span in the development of an organism when it is optimal for certain capacities to emerge because the organism is especially responsive to certain experiences.
Classical conditioning explains how neutral stimulus can acquire the capacity to elicit a response originally evoked by another stimulus. This kind of conditioning was originally described by Ivan Pavlov. Many kind of everyday responses are regulated through classical conditioning, including phobias, fears, and pleasant emotional responses. Even psychological responses such as immune and sexual functioning and drug tolerance can be influenced by classical conditioning. A conditioned response may be weakened and extinguished entirely when the CS is no longer paired with the US. In some case, spontaneous recovery occurs, and an extinguished response reappears after a period of non-exposure to CS. Conditioning may generalized to additional stimuli that are similar to the original CS. The opposite of generalization is discrimination, which involve not responding to stimuli that resemble the original CS. Higher order conditioning occurs when a CS function as if it were US, to establish new conditioning. Example: The art of manipulating people’s association has been perfected by the advertising industry. Advertisers consistently endeavor to pair the product they are pendling with stimuli that seem likely to elicit positive emotional response. Like advertisers, candidates running for election need to influence the attitude of many people quickly, subtly, and effectively- and they depend on evaluation conditioning to help them do so. For example , politician show-up at an endless variety of pleasant public events( such as opening of a new mall) that often have nothing to do with their public service.
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