Drugs and Behavior

4 of the 7 steps in neurotransmitter action

Synthesis of neurotransmitter made in the soma or terminal

Storage in vesicles

Release into synaptic cleft with exocytosis triggered by Ca2+ influx

Binding to receptors on postsynaptic membrane

Reuptake

Neurotransmitter is taken back into the presynaptic cell

enzymatic degradation

Enzyme breaks down neurotransmitter in the synaptic cleft

Diffusion

Nuerotransmitter drifts away from the synaptic cleft

ionotropic receptors

Fast acting, opens ion channels directly used for quick signaling

Metabotropic receptors

Slow acting, activates G proteins and has indirect ion channel effects

EPSP

Excitatory postsynaptic potential; a slight depolarization of a postsynaptic cell, bringing the membrane potential of that cell closer to the threshold for an action potential.

IPSP

Inhibitory postsynaptic potential; a slight hyperpolarization of the postysynaptic cell, moving the membrane potential of that cell further from threshold.

Presynaptic Membrane (axon terminal)

Where the action potential terminates to release the chemical message

Vesicles

small membrane sacs that specialize in moving products into, out of, and within a cell

postsynaptic membrane

the cell membrane opposite the terminal button in a synapse; the membrane of the cell that receives the message

Depolarization

Na⁺ channels open → Na⁺ rushes in → inside becomes positive.

Repolarization

K⁺ channels open → K⁺ flows out → inside becomes negative again.

Hyperpolarization

Too much K⁺ exits → membrane briefly more negative than resting.

What is the threshold for an axon?

-55mv

Electrical gated ion channel

Ion channels that open/close in response to changes in membrane voltage. At resting potential, these channels are closed. They only open when threshold is reached.

sodium-potassium pump

Pumps 3 NA+ ions out and 2 K+ ions in per cycle, keeps sodium high outside and potassium high inside which is essential for restoring and maintaining the resting potential

Dendrite

Branch like extensions that recieve signals from other neurons, the carry info towards the cell body.

Cell body (soma)

Contains the nucleus and organelles, integrates incoming signals and generates going out signals

Axon

Long fiber that conducts electrical impulses (action potentials) away from the cell body

Terminal ending

Small branches at the end of an axon that release neurotransmitters into the synapse

Blood Brain Barrier (BBB)

physiological barrier between the circulatory system and the central nervous system that establishes a privileged blood supply, restricting the flow of substances into the CNS

insufflation

Absorbing a drug through the nose; fast rise, but not as instant as IV

PO

Oral consumption of a drug; slower rise, longer peak, longer duration

Intravenous (IV)

directly into a vein; rapid spike then rapid decline

Dioscordes

Wrote De Materia Medica, one of the first systematic texts describing hundreds of medicinal plants and substances, including their psychoactive properties.

JJ Moreau de Tours

First Psychopharmacologist. He studied the effects of hashish (cannabis) in the 1840s, documenting its impact on mood, thought, and mental illness.

J.M.D Sharvell

First Behavioral Pharmacologist. He investigated how drugs alter behavioral responses, particularly looking at conditioned behavior and reinforcement.