Biological Influences on Behavior

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Please see response attached, which is also presented below. I hope this helps and take care.

RESPONSE:

1. Describe neurotransmitters, their function, and impact on behavior.

Function:

Neurotransmitters are chemicals whose main function is to relay, amplify and modulate electrical signals between a neuron and another cell (Source:http://en.wikipedia.org/wiki/Neurotransmitters).

Neural transmission is basically, what happens when information is sent from neuron to neuron. This transmission works at both the electrical and chemical levels. Whenever the room between the two is small enough the electrical signal can just continue on its way. The problem comes when the gap is too large and the signal has to be changed from electrical to chemical. The chemicals are neurotransmitters or chemicals that are released by neurons that carry information from one
neuron to another. The result is that the chemicals are received by a neuron met at a junction. (Online Medical Dictionary, 2006)

Description:

A chemical can be classified as a neurotransmitter if it meets the following conditions:

· It is synthesized endogenously, that is, within the presynaptic neuron;
· It is available in sufficient quantity in the presynaptic neuron to exert an effect on the postsynaptic neuron;
· Externally administered, it must mimic the endogenously-released substance; and
· A biochemical mechanism for inactivation must be present. http://en.wikipedia.org/wiki/Neurotransmitters

Impact on Behavior:

The impact on behavior is complex. That is,

· These chemicals and hormones need to be balanced in order to think "normally" which in turn impacts how we act (behave).
· These chemicals and hormones also relay messages to our muscles to respond in a balanced way, unless our chemicals and hormones become imbalanced (implicated in depression). (Source: http://en.wikipedia.org/wiki/Neurotransmitters).

Why are there so many brain neurotransmitters? Because the functions performed by brain neurotransmitters are not as uniform as they might superficially appear. Some (like glutamate) are excitatory, whereas others (like GABA) are primarily inhibitory. In many cases (as with dopamine) it is the receptor, which determines whether the transmitter is excitatory or inhibitory. Receptors can also determine whether a transmitter acts rapidly by direct action on an ion channel (e.g., nicotinic acetylcholine receptors) or slowly, by a second-messenger system that allows for synaptic plasticity (e.g., muscarinic acetylcholine receptors). Speed & mechanism of transmitter inactivation after the signal has been sent is also a factor. There are probably also costs & benefits involved in synthesizing, transporting and recycling various neurotransmitters in the differing chemical milieus of the brain (Source: http://www.benbest.com/science/anatmind/anatmd10.html#intro).
Thus, neurotransmitters of the brain are the chemicals released by nerve cells (neurons) at synapses that influence the activity of other cells. They are indeed specialized chemical messengers (e.g., acetylcholine, dopamine, norepinephrine, serotonin) that send a message from one nerve cell to another, because most neurotransmitters play different roles throughout the body, many of which are not yet known. Neurotransmitters may excite, inhibit, or otherwise influence the activity of cells (Source: www.ninds.nih.gov/health_and_medical/pubs/sci_report.htm).

See http://www.benbest.com/science/anatmind/anatmd10.html#intro for more detail on the function of different neurotransmitters (amino acids; peptides; monoamines - norepinephrine, dopamine & serotonin plus ...