PSYCHOLOGY PSY -847-05
1a What is the most significant difference between the roles of the peripheral and central nervous systems in shaping behavior? 1b Why?
2 a The peripheral and central nervous system pathways interact and integrate their functions to create a response to a stimulus. To what extent can the central
nervous system be trained to alter the autonomic response? 2b Is further alteration of the autonomic response improbable or undesirable? 2c Why do you believe this is
the limit?
3a When describing your dissertation, it is helpful to have a concise “elevator speech” ready about your topic in about 200 words or less. What is your topic, what is
the gap it will fill and how will you go about it? [No reference is needed for this DQ]
PSY 847 Biological Psychology
Lecture 2
Neurons and the Nervous System
Introduction
Knowing how neurons and the nervous system function provides a context from which to
understand how the brain controls human actions. This information will allow for further
examination regarding how the brain controls important day-to-day actions such as learning,
thinking, sensation, and perception. These functions are important in the everyday lives of
individuals, and they are of critical importance to educators and clinicians. Further, the ability to
explore how changes in neurons brought about by short-term or chronic chemical or physical
damage affect the ability of the brain to properly sustain itself is of particular interest to
researchers.
Neurotransmitters: The Chemical Messengers
When an electrical signal reaches the end of an axon, this causes the release of neurotransmitters
from their storage locations at the synapse. This changes the messenger from electrical to
chemical and is a critical part of neuron function. Neurotransmitters, therefore, are the chemical
messengers through which neurons communicate with each other. In fact, it is during the
chemical message process that most medications and drugs have their effects (Kandel, Schwartz,
& amp; Jessell, 2000).
The neurotransmitters carry their chemical message across the synaptic cleft to a neighboring
neuron. When the neurotransmitters are released, they reach the adjacent neuron within a few
nanoseconds (Foord et al., 2005). There they adhere to, or bind with, specific sites called
receptors. This receptor-binding activity causes the signaled neuron to activate. The chemical
signal is quickly converted to an electrical signal and flows down this next neuron to the next
group of synapses, where the neurotransmission process occurs again.
For the brain to function properly, neurons must correctly send these chemical messages to one
another. Many things are required for this communication to happen properly, including accurate
genetic development, appropriate developmental environment, proper nutrition, lack of
interfering toxic chemicals, and other factors. While many factors are long-term, some have an
immediate effect.
Different Neurotransmitters Means Different Messages
There are several different neurotransmitters. They all function similarly, but reside in different
neurons. For many years, it was believed that there could be only one neurotransmitter for one
neuron, but this has been proven not to be the case (Kandel et al., 2000). Because different
neurotransmitters send different messages, some neurotransmitters increase while others
decrease the firing rates (the number of action potentials) of neighboring neurons.
Neurotransmitters that increase, or speed up, firing rates are called excitatory neurotransmitters. Neurotransmitters that decrease, or slow down, the firing rates of
neighboring neurons are called
inhibitory neurotransmitters (Kandel et al.).
Different neurotransmitters reside in different neurons and in different parts of the brain to carry
out or coordinate different functions and actions. For example, to communicate with one another,
neurons in the reward pathways use the powerful excitatory neurotransmitter, dopamine. When
neurons fire and release dopamine in the reward pathways, feelings of euphoria and pleasure
result (Pierce & Kumaresan, 2006). It should be immediately clear, then, that anything that
increases the effects of dopamine will increase feelings of pleasure.
Key neurotransmitters include serotonin and the endogenous opiates. Serotonin is a
neurotransmitter that helps to regulate moods and to control emotions (Young & Leyton, 2002).
Serotonin plays an important role in many psychological problems, such as anxiety, depression,
obsessive-compulsive disorder, and overeating. The endogenous opiates are naturally occurring
morphine-like molecules used by the brain to regulate responses to both pain and pleasure.
A vital inhibitory neurotransmitter is called gamma-aminobutyric acid (GABA). As an inhibitory
neurotransmitter, GABA opens ion channels that allow negative ions into the neuron, making it
less likely to fire and inhibiting not only the brain’s ability to process information, but also its
ability to function normally (Kandel et al., 2000).
Glutamate is an important excitatory neurotransmitter that tends to be located throughout
