Dompaine and Gabba Neurotransmitters

Neurons and Action Potentials

• Action potentials are electrical impulses fired by neurons.

• They trigger the release of chemicals known as neurotransmitters into the synaptic space, the gap between two neurons.

• The axon of one neuron communicates signals across a synapse to the dendrites of another neuron.

Neurotransmitters

• Neurotransmitters are chemicals that enable communication between neurons, as well as with muscles and glands.

• Research in neuroscience has examined how neurotransmitters contribute to behavioral disorders.

Types of Neurotransmitters (Focus on Dopamine and GABA)

Dopamine

• Dopamine is categorized as an excitatory neurotransmitter.

• Its function:

  • When it binds to a receptor site on a receiving neuron, it opens sodium channels.

  • Sodium ions flow into the neuron, leading to depolarization and possibly an action potential.

• Involvement in:

  • Voluntary movement.

  • Emotional arousal.

  • Learning.

  • Reward pathways.

• Effects of drugs:

  • Substances like marijuana and heroin increase dopamine release, potentially leading to addiction.

Dopamine and Disorders

• Low levels of dopamine are linked to disorders like Parkinson's disease, caused by the degeneration of dopamine-releasing neurons in the substantia nigra.

  • Symptoms include uncontrollable tremors.

  • Treatment: L-dopa, a chemical that converts to dopamine, helps manage symptoms.

• High levels of dopamine are associated with schizophrenia:

  • The dopamine hypothesis states that excess dopamine in certain neural circuits leads to symptoms like hallucinations and delusions.

  • Evidence includes:

    • Schizophrenic individuals often have more dopamine receptors, which are overactive.

    • Antipsychotic drugs are effective by blocking dopamine receptor sites, subsequently slowing down nerve impulses.

GABA (Gamma-Aminobutyric Acid)

• GABA is the primary inhibitory neurotransmitter in the brain.

  • It works oppositely to excitatory neurotransmitters, causing either potassium ions to leave or chloride ions to enter a neuron.

  • This action increases the neuron's negativity, making it harder to fire.

• Role in:

  • Learning and memory.

  • Regulating sleep.

  • Dampening neural activity in areas linked to anxiety, such as the amygdala.

GABA and Anxiety Disorders

• Low levels of GABA may result in heightened nervous systems and increased anxiety responses to stressors.

• Research shows that individuals with panic attack histories have a 22% lower concentration of GABA in the occipital cortex than control subjects.

  • This suggests susceptibility to classically conditioned phobias due to existing arousal responses.

• Antianxiety medications often target GABA receptors:

  • Buspirone works by blocking serotonin receptors and enhancing GABA activity, thus reducing emotional arousal in overactive brain areas.

Conclusion

• Neurotransmitters, such as dopamine and GABA, play crucial roles in neuron communication.

• The balance of excitatory and inhibitory neurotransmitters is vital for maintaining healthy brain function and emotional regulation.