How Do Neurotransmitters Influence Behavior?

NTs influence our motions and emotions… NTs influence our motions and emotions… Particular pathways in the brain may only use 1 or 2 NTs & particular NTs have particular effects on behavior & emotions. Particular pathways in the brain may only use 1 or 2 NTs & particular NTs have particular effects on behavior & emotions. i.e.: ACh is one of the best understood NTs. i.e.: ACh is one of the best understood NTs. *Major role in learning & memory every junction btwn motor neuron & skeletal muscle…resulting in the neuron & skeletal muscle…resulting in the muscle contracting *If ACh transmission is blocked (anesthesia) muscles can’t contract & we are paralyzed

NT Pathways: Each of the brain’s differing NTs has designated pathways where it operates

The Function of the NT depends on which part of the brain it acts upon: If NT is acting in brainstem, it affects basic functions…breathing, heartbeat If NT is acting in brainstem, it affects basic functions…breathing, heartbeat If NT is acting on areas in midbrain, it affects functions like memory & emotion If NT is acting on areas in midbrain, it affects functions like memory & emotion If NT acts on the cortex, higher functions like memory integration, problem solving & perception are affected If NT acts on the cortex, higher functions like memory integration, problem solving & perception are affected

How Drugs & Other Chemicals Alter Neurotransmission Drugs & other chemicals affect brain chemistry at synapses by either amplifying or blocking a NTs activity. Drugs & other chemicals affect brain chemistry at synapses by either amplifying or blocking a NTs activity. An agonist molecule may be similar enough to a NT to bind to its receptor & mimic its effects. An agonist molecule may be similar enough to a NT to bind to its receptor & mimic its effects. *i.e.: some opiate drugs are agonists & produce temporary “high” by amplifying normal sensations of arousal/pleasure Dopamine is similar to cocaine Serotonin is similar to LSD & Ecstasy *i.e.: black widow spider venom = floods synapses with ACh = muscle contractions, convulsions & possible death.

Antagonists also bind to receptors but their effect is instead to block a NTs functioning. Antagonists also bind to receptors but their effect is instead to block a NTs functioning. i.e.: Botulin (a poison that can form in improperly canned food causes paralysis by blocking Ach) i.e.: Botulin (a poison that can form in improperly canned food causes paralysis by blocking Ach) Botox – paralyzes facial muscles

So…if endorphins lessen pain & boost mood, why not flood the brain with artificial opiates? When flooded with opiate drugs (heroin/morphine) the brain may stop producing its own natural opiates. When flooded with opiate drugs (heroin/morphine) the brain may stop producing its own natural opiates. When the drugs are withdrawn, the brain is then deprived of any form of opiate. When the drugs are withdrawn, the brain is then deprived of any form of opiate.

In order for drugs to have an effect: In order for drugs to have an effect: *must be accompanying receptor site on neuron that matches structure of drug that matches structure of drug

The Blood-Brain Barrier Protects the brain from "foreign substances" in the blood that may injure the brain. Protects the brain from "foreign substances" in the blood that may injure the brain. Protects the brain from hormones and neurotransmitters in the rest of the body. Protects the brain from hormones and neurotransmitters in the rest of the body. Maintains a constant environment for the brain. Maintains a constant environment for the brain.

Not all substances can pass through the BBB… Not all substances can pass through the BBB… *i.e.: Parkinson’s patients can’t simply take dopamine to alleviate their symptoms. dopamine to alleviate their symptoms. They must take a precursor of dopamine They must take a precursor of dopamine called L-dopa that will metabolize into dopamine once it reaches the brain called L-dopa that will metabolize into dopamine once it reaches the brain

PLEASE DO NOW! Recall a time when the endorphin response may have protected you from feeling extreme pain?