neurotransmitter (thing)

Acetylcholine:

• Affects arousal, attention, memory, motivation, movement. Too much can cause spasms or tremors. Too little can cause paralysis or torpor.

Dopamine:

• Inhibits wide range of behavior and emotions, including pleasure. Implicated in schizophrenia and Parkinson's Disease.

Serotonin:

• Inhibits virtually all activities. Important for sleep onset, mood, eating behavior.

Norepinephrine:

• Affects arousal, wakefulness, learning, memory, mood.

Endorphins and Enkephalins:

• Inhibits transmission of pain messages.