Human Physiology/The Nervous System

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postsynaptic potential (IPSP). It makes it harder for the neuron to depolarize and hence harder for it to fire an action

potential, slowing neural function. At higher doses alcohol will start to block NMDA. NMDA is involved in memory

(see the long-term potentiation section) so this is thought to account for memory blackouts.

Methamphetamine

In the US, medically prescribed 

methamphetamine 

is distributed in tablet form under the brand name Desoxyn®,

generally for Attention Deficit Hyperactivity Disorder (ADHD) but also for narcolepsy or obesity.

Illicit methamphetamine comes in a variety of forms. Most commonly it is found as a colorless crystalline solid, sold

on the street under a variety of names, such as: crystal meth or crystal. Methamphetamine may also be referred to as

shards, rock, pony, crissie, crystal, glass, ice, Jib, critter, Tina, tweak or crank. Dope may refer to methamphetamine

or other drugs, especially heroin or marijuana. The term "speed" can denote any stimulant including other

amphetamines (e.g. adderall), cocaine and methylphenidate (Ritalin).

Methamphetamine can be injected (either subcutaneous, intramuscular or intravenous), smoked, snorted, swallowed,

or used rectally or sublingually. The latter two being fairly uncommon. After administration, methamphetamine

takes from a few seconds (smoked or injected IV) to around 30 minutes (oral) for effects to arise, lasting around

eight hours depending on the route of administration. Effects/side effects include euphoria, anorexia, increased

energy, clenching of the jaw/grinding of teeth (bruxism), weight loss, insomnia, tooth decay and psychosis among

others.

Methamphetamine is neurotoxic to at least some areas of the brain, and owes most of it's effects to the

neurotransmitters dopamine, norepinephrine and serotonin it releases. It also blocks the reuptake of those

neurotransmitters, causing them to stay in the synaptic cleft longer than normal.