Introduction to Psychology: Neuroscience and Behavior

Introduction to Psychology: Neuroscience and Behavior

I. Biological Bases of Behavior

A. Basic Cell Functioning

  • 1. Anatomy

    • a. Cell Body:

      • The part of the neuron that houses the nucleus and supports basic cellular processes.

    • Responsible for maintaining the life of the neuron.

    • Contains cytoplasm, cell membrane, and organelles.

    • b. Axon:

      • A long, slender projection of a neuron that typically conducts electrical impulses away from the cell body.
      • May be myelinated, leading to faster transmission of signals.
      • Ends at the axon terminals, where neurotransmitters are released.

    • c. Dendrites:

      • Branch-like structures that receive messages from other neurons and transmit them to the cell body.
      • Increase the surface area for receiving signals from multiple neurons.

B. Communication

  • 1. Neurotransmitters:

    • Chemical messengers that transmit signals across a synapse from one neuron to another.

  • 2. Reuptake:

    • The process by which neurotransmitters are reabsorbed by the neuron that released them, terminating the signal.

  • 3. Breakdown:

    • The process by which enzymes decompose neurotransmitters in the synaptic cleft, rendering them inactive.

  • 4. Receptor Sites:

    • Specific areas on the postsynaptic neuron where neurotransmitters bind, initiating a response in the receiving neuron.

II. Brain Chemistry

A. Acetylcholine (ACh)

  • A critical neurotransmitter involved in muscle activation and memory processes.

    • a. Botulinus Toxin (Botulism):

      • A potent neurotoxin that inhibits the release of ACh, leading to paralysis.

    • b. Curare Poison and Cobra Venom:

      • Both interfere with the transmission of ACh at neuromuscular junctions, causing muscle paralysis.

    • c. Black Widow Venom and Some Chemical Warfare Agents:

      • Can cause an excessive release of ACh leading to over-excitation of muscles and potential death.

B. Norepinephrine (NE)

  • A neurotransmitter involved in arousal and alertness.

    • a. Amphetamines:

      • Stimulants that increase the release of norepinephrine, leading to heightened alertness and energy.

    • b. Reserpine:

      • A drug that decreases norepinephrine levels, which can lead to sedation and lower blood pressure.

C. Dopamine

  • A neurotransmitter associated with reward, motivation, and motor control.

    • a. Parkinson’s Disease:

      • A neurodegenerative disorder characterized by low dopamine levels, leading to motor symptoms such as tremors and rigidity.

    • b. Schizophrenia:

      • A mental disorder thought to be linked with high levels of dopamine, leading to symptoms such as hallucinations and delusions.

D. Serotonin

  • A neurotransmitter that contributes to the regulation of mood, appetite, and sleep.

    • a. Depression:

      • Often associated with low levels of serotonin; treatment may involve selective serotonin reuptake inhibitors (SSRIs) to increase serotonin availability.

    • b. LSD:

      • A hallucinogenic drug that affects serotonin receptors, leading to altered states of consciousness.

E. GABA

  • The primary inhibitory neurotransmitter in the brain, crucial for regulating neuronal excitability.

    • a. Valium:

      • A drug that enhances the effect of GABA, providing anxiolytic (anxiety-reducing) effects.

    • b. Alcohol:

      • Acts as a GABA agonist, causing sedation and impairing motor coordination.

F. Endorphins

  • Neuromodulators that help relieve pain and induce feelings of pleasure or euphoria.

    • a. Acupuncture:

      • A technique that may stimulate endorphin release, contributing to pain relief and relaxation.

    • b. Opiates (heroin, morphine, codeine, etc.):

      • Drugs that bind to endorphin receptors, producing significant pain relief and euphoria, but also carry a risk for addiction.