neurotransmitters and psychopharmacology

Overview of Neural Transmission

1. Neural Transmission Process

   • Sending messages through neurons.

   • Culminates at the axon terminal button where neurotransmitters are released.

   • Vesicles with neurotransmitters are ready to be released into the synaptic gap.

2. Role of Neurotransmitters

   • Categorized as excitatory or inhibitory.

     • Excitatory Neurotransmitters: e.g., dopamine; stimulate the postsynaptic neuron.

     • Inhibitory Neurotransmitters: dampen the response.

   • Released into the synapse via exocytosis and bind to receptor sites on the postsynaptic neuron.

3. Synaptic Processes

   • Postsynaptic neuron decides if the signal is sent based on excitatory input strength.

   • Requires reaching a critical threshold of -55 millivolts to trigger an action potential.

   • If not enough stimulation, excess neurotransmitters are absorbed via reuptake.

4. Excitatory and Inhibitory Potentials

   • EPSPs: Small depolarizations that bring a neuron closer to firing.

   • IPSPs: Hyperpolarize the neuron, making it less likely to fire.

5. Summation of Potentials

   • Spatial Summation: Multiple stimuli from different locations combine to reach the threshold.

   • Temporal Summation: Multiple stimuli at the same location over time can lead to an action potential.

6. Agonists and Antagonists

   • Agonists: Enhance neurotransmitter effects by binding to receptor sites.

   • Antagonists: Block receptor sites, preventing neurotransmitter action.

7. Key Neurotransmitters

   • Dopamine: Involved in pleasure and reward.

   • Serotonin: Regulates mood and emotional stability.

   • GABA: Promotes calmness and reduces anxiety.

   • Acetylcholine: Important for learning and memory.

   • Endorphins: Natural painkillers and involved in stress responses.

8. Addiction and Neurotransmitters

   • Nucleus accumbens crucial in addiction, influenced by dopamine.

   • Cycle of increasing substance intake leads to dependency.

   • Synthetic drugs suppress natural neurotransmitter action.

9. Emotional Impact of Addiction

   • Low affect: Diminished emotional response and challenges in feeling pleasure without substances.

10. Neurotransmitter Dynamics in Addiction

    • Reward system stimulated by dopamine reinforces desire for substances.

11. Dopamine Hypothesis

    • Excessive stimulation leads to neuroadaptation and higher demand for dopamine.

12. Cognitive Effects

    • Overstimulation can cause burnout of dopamine receptors, affecting cognitive functionality.

13. Withdrawal and Recovery

    • Symptoms vary by substance, with some like heroin withdrawal lasting weeks.

    • Treatments include agonist and antagonist therapies but come with overdose risks post-relapse.

14. Psychopharmacology

    • Studies the effects of drugs on cognition and behavior.

    • Antipsychotics: Block dopamine and serotonin receptors.

    • Antidepressants: SSRIs block reuptake of serotonin.

    • Anti-anxiety drugs: Benzodiazepines enhance GABA effects.

15. Stimulants and Depressants

    • Stimulants: Increase release and inhibit reuptake of neurotransmitters, enhancing mood.

    • Depressants: Stimulate GABA receptors, promoting relaxation.