Psych 202 Lecture 4a slide notes

Page 1: Introduction to the School of Psychology

• The University of Auckland

• Faculty of Science

• Centre for Brain Research

• Cognitive Neuroscience Subject List:

  • Cognitive Neuroimaging

  • Neurodevelopment

  • Neurogenetics

  • Transmitters and Drugs

Page 2: Objectives of Study

• Understand the role of neurotransmitters in synaptic transmission.

• Familiarize with common neurotransmitters and their functions.

• Learn about the effects of commonly used drugs at the synapse.

Page 3: Overview of the Synapse

• Definition and structure of a synapse.

Page 4: Components of the Synapse

• Cell body

• Axon terminal

• Axon

Page 5: Processes of Synaptic Transmission

1. Neurotransmitter Release:

   • Neurotransmitters are stored in vesicles within the axon until neuron stimulation.

2. The Synaptic Space:

   • The small gap between the axon terminal of one neuron and the dendrite of another.

3. Binding Process:

   • Neurotransmitter binds to receptor sites on the next neuron's dendrites, leading to potential changes.

Page 6: Ionotropic Receptors

• Structure of Ionotropic Receptors:

  • Binding site for neurotransmitters that opens or closes ion channels, affecting ion flow.

Page 7: Ionic Movements and Postsynaptic Potentials

• Key Events During Postsynaptic Potential:

  • Influx of Na+ leads to depolarization (EPSP).

  • Efflux of K+ causes hyperpolarization (IPSP).

  • Ca2+ influx also results in hyperpolarization (IPSP).

Page 8: Key and Lock Model of Transmitter Action

• Model:

  • Each neurotransmitter fits a specific receptor like a key in a lock.

  • Example: Acetylcholine (ACh), GABA.

Page 9: Types of Receptor Mechanisms

• Ion-Channel Linked Receptors:

  • Fast acting, alter ion flow directly.

• G-Protein Linked Receptors:

  • Slower, leading to long-lasting effects through second messengers.

Page 10: Mechanism of G-Protein Linked Receptors

1. Neurotransmitter activates receptor.

2. Receptor activates G-protein, which stimulates adenylyl cyclase to convert ATP to cAMP.

3. cAMP subsequently activates protein kinase A (PKA).

Page 11: Drug Actions on Receptors

• Agonist Drugs:

  • Mimic neurotransmitter action.

• Antagonist Drugs:

  • Block neurotransmitter action.

Page 12: Overview of Acetylcholine (ACh)

• Excitatory transmitter with two types of receptors:

  • Ionotropic: opens Na+ channels (EPSP).

  • Metabotropic: opens K+ channels (IPSP).

Page 13: Ionic Movements and Effects

• Repeated concepts of ionic movements during postsynaptic potentials, focusing on Na+, K+, and Ca2+ and their specific roles in depolarization and hyperpolarization.

Page 14: Acetylcholinergic Neuron Distribution

• Schematic overview of important groups of acetylcholinergic neurons in the rat brain.

Page 15: Cholinergic Drug Actions

• Antagonists:

  • Example: Curare, causing paralysis.

• Agonists:

  • Nicotine enhances attention/arousal, and anti-cholinesterases prolong ACh action (e.g. Physostigmine).

Page 16: Neurotransmitter Deactivation Mechanisms

• Reuptake: Process wherein neurotransmitter molecules are reabsorbed from the synaptic cleft.

• Enzymatic Degradation: Breakdown of neurotransmitters by enzymes.

Page 17: Overview of Glutamate (Glu)

• An excitatory transmitter that causes Na+ influx resulting in EPSPs; functions through both ionotropic and metabotropic receptors.

Page 18: Ionic Movements and Postsynaptic Potentials (Repeated)

• Details of ion channel interactions and their impact on neuronal action potentials reiterating the roles of Na+, K+, and Ca2+.

Page 19: Glutamate Receptor Actions

• Antagonist: Phencyclidine (PCP) causing euphoria and psychotic behavior.

• Agonists: AMPA, NMDA, kainic acid facilitating glutamate activity.

Page 20: Overview of Dopamine

• A versatile neurotransmitter that can be both excitatory and inhibitory; has several subtypes affecting transmission differently.

Page 21: Distribution of Dopaminergic Neurons

• Schematic representation showing distribution of dopaminergic neuron groups in the rat brain, focusing on areas like the neocortex, hippocampus, and various nuclei.

Page 22: Dopamine-related Drugs

• Drugs that decrease transmission:

  • Risperdal and Zyprexa (antipsychotics).

• Drugs that increase transmission:

  • Amphetamines and cocaine, impacting multiple neurotransmitters.

Page 23: Overview of Serotonin (5-HT)

• Can be excitatory or inhibitory, working via multiple mechanisms affecting cellular cAMP levels.

• Specific receptor types identified by their coupling mechanisms and potential effects.

Page 24: Distribution of Serotonergic Neurons

• Schematic overview detailing the distribution of serotonergic neurons across various brain structures.

Page 25: Serotonin-related Pharmaceuticals

• Drugs increasing serotonin transmission:

  • SSRIs like Prozac (Fluoxetine) and Zoloft for depression relief.

• Drugs decreasing transmission:

  • Antipsychotics such as Risperdal and Zyprexa.

Page 26: Neurotransmitter Deactivation Mechanism (Repeated)

• Discusses reuptake and enzymatic degradation of neurotransmitters.

Page 27: Overview of GABA (Gamma-Aminobutyric Acid)

• An inhibitory neurotransmitter that opens Cl- channels leading to IPSPs. It has both ionotropic (GABAA) and metabotropic (GABAB) receptor types.

Page 28: Ionic Movements During GABAergic Transmission

• Similar concepts focusing on GABA's ionic effects in the context of postsynaptic potentials.

Page 29: GABAergic Drugs

• GABAA Agonists:

  • Example: Benzodiazepines, aiding in anxiety reduction.

• GABAA Antagonists:

  • Example: Bicuculline, associated with seizure risks.

Page 30: GABA Receptor Schematic

• Illustration of GABA receptor binding sites and their functions.

Page 31: Overview of RO15-4513

• RO15-4513 as an alcohol antagonist.

Page 32: Effects of RO15-4513

• Study demonstrating the effects of alcohol and RO15-4513 on behavior in rats.