1. Psychoactive Drugs: THC & Cocaine
Rowan Palmour and Michael Silver

2. Drugs Foreign chemical (non-food) substances
Artificially introduced into the body
Cause a change in the functioning of the body
Psychoactive Drugs affect the brain and personality
Drugs: chemical substances that are ingested, injected, inhale or put into the body in some other way, to cause a change in the functioning of the body

3. Excitatory and Inhibitory Drugs
Excitatory Drugs promote/inhibit synaptic transmission at excitatory/inhibitory synapses
Nicotine, Cocaine, Amphetamines
Inhibitory Drugs block the release of excitatory neurotransmitters
Benzodiazepines, Alcohol, THC
Excitatory Drugs: Either promote synaptic transmission at excitatory synapses or inhibit transmission at inhibitory synapses
Inhibitory Drugs: Do the opposite (I guess inhibit at excitatory and excite at inhibitory?)

4. Review of Neurons and Synapses
Synapse- a junction between two neurons
Neurotransmitters- chemicals that pass messages across the synapse
Neurotransmitters- chemicals that pass messages from the pre-synaptic neuron to the post-synaptic neuron

5. Synaptic Transmission

6. Variety of Ways Psychoactive Drugs Affect Synaptic Transmission
Some bind to neurotransmitter receptors in postsynaptic membrane, blocking the receptor
Others have the same effect as neurotransmitters, but aren’t broken down
Some prolong the effect of neurotransmitters
Some have similar chemical structure to neurotransmitters, bind to receptors for that neurotransmitter in postsynaptic membranes, thus blocking the receptor
2. Others w/ similar chemical structures to ntransmitters have the same effect as a ntransmitter, but they're not broken down, so the effect of binding to the receptor lasts much longer
3. Some interfere with breakdown of ntransmitters in synapses or reabsorption into the presynaptic neuron, thus prolonging the effect of ntransmitters

7. Addiction Addiction is dependence on a particular substance
Heavily studied
3 factors increase the levels of addiction
Dopamine Secretion
Genetic Predisposition
Social Factors
Now we will transition to the addictive aspects of psychoactive drugs.
The definition of addiction is: being physically and mentally dependent on a particular substance, and being unable to stop taking it without incurring adverse effects
Addiction has been heavily studied, since it is responsible for a lot of physical and social damage
Three factors increase levels of addiction, esp. when combined

8. 1. Dopamine Secretion Some drugs are addictive, some not
Many addictive drugs use dopamine as a neurotransmitter in the synapses
These synapses are involved in the reward pathway
Many drugs users become dependent on the feeling dopamine promotes
The drug itself may determine the addiction- some are addictive, some not
Many addictive drugs use dopamine as a neurotransmitter to stimulate transmission. The corresponding synapses are involved in the reward pathway, giving us feelings of well-being and pleasure
Many drug users are unable to stop because they are dependent on or addicted to the feelings dopamine promotes

9. 2. Genetic Predisposition
Some addictions are more common in certain families
This implies an “addict gene”
Although many drugs are addictive, not all users become addicts
Addictions (esp. alcoholism) are much commoner in certain families. This suggests that genes make people predisposed
Scientists are currently researching what gene makes people predisposed

10. 3. Social Factors
Addiction can be prevented or encouraged by social factors
Cultural traditions, peer pressure, poverty and social depravation, traumatic life experiences, mental health problems
Still not certain how genetic predispositions may affect addictions... social factors can either prevent of encourage it
Some examples of social factors are: Cultural traditions, peer pressure, poverty and social depravation, traumatic life experiences, mental health problems

11. Cocaine Excitatory psychoactive drug
Stimulates transmission in the brain at synapses that use dopamine as a neurotransmitter
Binds to membrane proteins that pump dopamine back into the presynaptic neuron
Cocaine is an excitatory psychoactive drug
Dopamine is the neurotransmitter used by the synapses associated with pleasurable feelings, like eating or having sex

12. Effect of Cocaine at Synapse
Dopamine transporters remove dopamine molecules from the synaptic cleft
Cocaine blocks dopamine transporter
Dopamine is trapped in the synaptic cleft
Dopamine binds repeatedly to the receptors
The nerve cell become overstimulated

13. Short-Term Effects of Cocaine
Continuous transmission at these synapses causes:
Euphoria
Increased Energy
Alertness
Talkativeness
Cocaine gives continuous transmission at these synapses, causing euphoria, as well as increased energy, alertness, talkativeness

14. Long-Term Effects of Cocaine
The body reduces natural secretion of dopamine
This explains cocaine-induced depression
Crack forms a vapor when heated
It is a more intense and addictive form of cocaine
The body adapts to cocaine by reducing secretion, as evidenced by post-mortem brains of cocaine users having lower than normal levels of dopamine
To recreate the original “high” from the earlier amounts of dopamine released by the body, cocaine users take larger doses
Crack- form of cocaine that forms a vapor when it is heated. It can be inhaled and absorbed rapidly, giving very intense effects. These factors cause greater addiction/overdose problems than other cocaine forms

15. THC (tetrahydrocannabinol)
One of the chemicals in cannabis
Inhibitory psychoactive drug
Binds to cannabinoid receptors, blocking the release of excitatory neurotransmitter molecules
Cannabinoid Receptors are found in synapses in various parts of the brain
The postsynaptic neuron releases a chemical that binds to the receptors in the membrane of the presynaptic neuron

16. Effect of THC at Synapse
Inhibitory Neurotransmitters are naturally active in the synapse to inhibit dopamine release
Anandamine removes short term memories and makes us feel relaxed and calm
Cannabinoid Receptors turn off the release of inhibitory neurotransmitters
THC mimics anandamine
Anandamine breaks down quickly, while THC does not

17. Short-Term Effects of THC
Disruption of psychomotor behavior
Memory impairment
Intoxication
Stimulation of Appetite

18. Sources
Allott, Andrew. "Neurobiology and Behavior." Biology for the IB Diploma: Standard and Higher Level. Oxford: Oxford UP, Print.
"Mouse Party." Mouse Party. University of Utah, n.d. Web. 17 Apr