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

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

Neuro 101: Signal Transduction

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”

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

Neuro 101: Signal Transduction YouTube video – Animation of Action Potential https://www.youtube.com/watch?v=yQ-wQsEK21E 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

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

Neuro 102: The Synapse

Neuro 102: The Synapse

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

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)

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

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

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

Neuro 102: Neurohormones

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

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