1. Psychology 320: The Biology of Motivation
How does the brain “motivate” behavior? (Neuro 102: Synapse, Neurotransmitters, and Hormones)
Psychology 320: The Biology of Motivation

2. Oligodendrocite (CNS)
Neuro 101: The Neuron
Dendrite
Terminal Button
Nodes of Ranvier
Soma/Cell Body
Axon
Oligodendrocite (CNS) or
Schwann (PNS) Cell
Myelin Sheath
Nucleus

3. Neuro 101: Signal Transduction

4. Neuro 101: Signal Transduction
These channels keep a very specific ion gradient in place
Based off of where it moves/holds specific ions
This results in the “internal milieu” resulting in a collective electrical charge far more negative than the “external milieu”

5. Neuro 101: The Action Potential
At “Resting State”
Something “stimulates” or “excites” the neuron

6. Neuro 101: Signal Transduction
YouTube video – Animation of Action Potential
So what “stimulates” the opening of Na+ channels?
They are “voltage gated” – meaning anything that makes the inside more positive (i.e., lets in + charged ions)
I.e. – Receptors OR other nearby Na+ channels

7. Neuro 102: Signal Transduction
So – In short:
The nerve impulse travels down axon
The positive change in ion concentration in terminal stimulates the “docking” and “release” of vesicles containing neurotransmitter
The neurotransmitter is released into the synaptic cleft
The neurotransmitter binds to receptors on the adjacent neuron, which then open ion channels allowing in selected ions (depending on type)
Excitatory make the inside more positive and thus more prone to further signal propagation
Inhibitory make the inside more negative and thus less prone to further signal propagation

8. Neuro 102: The Synapse

9. Neuro 102: The Synapse

10. Neuro 102: The Receptors Acetylcholine Receptor Memory Fear Thoughts
Stress
Executive Function
Motor Movement
Reward
Nicotine
Sleep
Alzheimer’s

11. Neuro 102: The Receptors Serotonin Receptor Mood MDD Depression GAD
Anxiety
PTSD
Happiness
Schizophrenia
Aggression
Migraine
Memory
Antiemetics
Sleep
Parkinson’s
Consciousness
Appetite Suppression (obesity)
Cardiovascular
Nausea
Premenstrual Syndrome
Digestion
Irritable Bowel Syndrome
SSRIs
LSD
MAOIs
Mescaline
Ondansetron
DMT
Imitrex/Relpax
MDMA (E)

12. Neuro 102: Some Common Neurotransmitters
Excitatory Neurotransmitters:
Glutamate – involved in a lot of stuff, especially memory, schizophrenia
PCP, special K, dextromethorphan
Acetylcholine – movement, arousal, attention, emotion, memory, learning
Nicotine, Cotinine, Physostigmine
Epinephrine (Adrenaline) – sleep, alertness, Fight-or-Flight
Norepinephrine (Noradrenaline) – mood (depression, anxiety), memory, sleep, wakefulness, hunger
Histamine – immune, wakefulness
Inhibitory
GABA – just about everything, especially sleep and anxiety
Xanax, Valium, Clonazepam, Zolpidem - and to some extent, Alcohol
Both Inhibitory and Excitatory
Serotonin – mood (depression, anxiety), sleep, appetite, thermoregulation
Dopamine – reward, cognition, mood, aversion, memory, sex

13. Neuro 102: Neuromodulators
Neurotransmitter Single synapse, neuron to neuron
Neuromodulator Multiple synapses, many neurons
OR Nearby neuron, single synapse
All neuromodulators
are neurotransmitters…
but
not all neurotransmitters are neuromodulators

14. Neuro 102: Neuro/hormones
Neurohormones and hormones
Neurohormones – Released from nerve cells into periphery
Hormones – Released from periphery into nerve cells

15. Neuro 102: Neurohormones

16. Neuro 102: Hormones act on neurons in various ways
Estrogen
Testosterone
- Or -
Estrogens
Androgens
Oxytocin
Vasopressin

17. Wrapping it up! Finally…
When the inside of the neuron gets more positively charged, Action Potentials result – “firing” or “stimulating” the cell
Action Potentials lead to release of neurotransmitter, a specific type of protein that leads to specific behavioral functions
Neurotransmitters cross the synaptic cleft (or synapse) and bind to specific receptor on nearby neuron’s dendrite
Receptors allow for that nearby cell to become more positive inside or more negative – which results in more “voltage-gated” Na+ (sodium) channels to open to create a new Action Potential