|
Contents:
1 through 8
Click on the images to see a larger version [file sizes range from 62K
to 190K], once you have viewed the image, use the "Back" button on your
browser to return to this page
|
1: Understanding Drug Abuse and Addiction: What Science
Says
Title
|
|
|
2: Drug addiction: a complex illness
Drug addiction is a complex illness. The path to drug addiction
begins with the act of taking drugs. Over time, a person's ability
to choose not to take drugs is compromised. This, in large part, is
a result of the effects of prolonged drug use on brain functioning,
and thus on behavior. Addiction, therefore, is characterized by
compulsive drug craving, seeking, and use that persists even
in the face of negative consequences.
|
|
|
3: Brain regions and their functions
Certain parts of the brain govern specific functions. For example,
the cerebellum is involved with coordination; the hippocampus with
memory. Nerve cells (neurons) are the basic unit of communication
in the brain. Information is relayed from one area of the brain
to other areas through complex circuits of interconnected neurons.
Information via electrical impulses transmitted from one neuron
to many others is done through a process called "neurotransmission."
|
|
|
4: The reward pathway
One pathway important to understanding the effects of drugs on
the brain is called the reward pathway. The reward pathway involves
several parts of the brain, some of which are highlighted in this
image: the ventral tegmental area (VTA), the nucleus accumbens,
and the prefrontal cortex. When activated by a rewarding stimulus
(e.g., food, water, sex), information travels from the VTA to the
nucleus accumbens and then up to the prefrontal cortex.
|
|
|
5: Where cocaine has its effects in the brain
Using cocaine as an example, we can describe how drugs interfere
with brain functioning. When a person snorts, smokes, or injects
cocaine, it travels to the brain via the bloodstream. Although it
reaches all areas of the brain, its euphoric effects are mediated
in a few specific areas, especially those associated with the reward
pathway discussed in the previous image.
|
|
|
6: Neurotransmission
As mentioned earlier (image 3), information is communicated in
the brain via a process called neurotransmission. Neurotransmission
involves a variety of chemical substances called "neurotransmitters."
One such neurotransmitter is called "dopamine." In the normal communication
process, dopamine is released by a neuron into the synapse (the
small gap between neurons). The dopamine then binds with specialized
proteins called "dopamine receptors" (see image) on the neighboring
neuron, thereby sending a signal to that neuron.
|
|
|
7: Neurotransmission (continued)
After the signal is sent to the neighboring neuron, dopamine is
transported back to the neuron from which it was released by another
specialized protein, the "dopamine transporter" (see image).
|
|
|
8: Cocaine and neurotransmission
Drugs of abuse are able to interfere with this normal communication
process in the brain. Cocaine, for example, blocks the removal of
dopamine from the synapse by binding to the dopamine transporters.
As shown in this image, this results in a buildup of dopamine in
the synapse. In turn, this causes a continuous stimulation of receiving
neurons, probably responsible for the euphoria reported by cocaine
abusers.
|
[Previous Section] [Next
Section]
|
|
Teacher Information
Here are some other NIDA-related sites which may be of interest.
Click on any of the links below to view those sites.
|
|