Biopsychology & Brain Function Lecture

Biopsychology

• Explores biological mechanisms underlying behavior.
  • Genetics: Impact of inherited genes on physiological and psychological traits.
  • Nervous system: Structure and function; interaction with the endocrine system.
  • Brain imaging techniques: PET, CT, fMRI for studying brain function.

Human Genetics

• Helps understand biological basis of behaviors, thoughts, and reactions.
  • Examples:
  • Different outcomes from same disease.
  • Genetic components in psychological disorders.
  • Inheritance of genetic diseases.

Theory of Evolution

• Natural selection: Organisms better suited survive and reproduce.
  • Adaptability is key to survival.
  • Characteristics impacting survival: protection from predators, access to food, offspring survival.

Genetic Variation

• Genetic difference between individuals.
• Begins with egg (23 chromosomes) and sperm (23 chromosomes) fertilization.
  • Chromosome: DNA strand.
  • DNA: Helix-shaped molecule of nucleotide base pairs.
  • Gene: DNA sequence controlling traits.
  • Allele: Specific version of a gene.

Genotype vs Phenotype

• Genotype: Genetic makeup.
• Phenotype: Observable characteristics.

Dominant vs Recessive Alleles

• Polygenic traits: Controlled by more than one gene.
• Alleles: Dominant or recessive.
  • Dominant allele: Expressed if inherited from one or both parents.
  • Recessive allele: Expressed only if homozygous (inherited from both parents).
  • Heterozygous: Two different alleles (Aa).
  • Homozygous: Two identical alleles (AA/aa).

Punnett Squares

• Tool to predict gene interaction in offspring.
• Mutations: Sudden, permanent gene change; can be harmful or beneficial.

Gene-Environment Interactions

• Nature and nurture interaction.
  • Range of reaction: Genes set boundaries; environment determines placement within range.
  • Genetic environmental correlation: Genes affect environment; environment influences gene expression.
  • Epigenetics: Study of how same genotype leads to different phenotypes.

Neuron Structure

• Semi-permeable membrane: Allows passage of small/uncharged molecules.
• Dendrites: Receive incoming signals.
• Axon: Transmits signals.

Myelin Sheath

• Fatty substance insulating axons for quicker signal travel.

Synapse

• Space between terminal button of one neuron and dendrite of another.

Resting Potential

• Na^+ more concentrated outside the cell.
• K^+ more concentrated inside the cell.

Action Potential

1. Neurotransmitters bind to receptors on dendrites, altering membrane potential.
   • Depolarization: Membrane becomes less negative, increasing firing likelihood.
   • Hyperpolarization: Membrane becomes more negative, decreasing firing likelihood.
2. Reaching threshold of excitation triggers action potential.
   • Threshold of excitation: Charge level for neuron activation.
   • Action Potential: Electrical signal.
   • All-or-none principle: Signal either reaches threshold or it doesn't.

Reuptake

• Reabsorption of neurotransmitters from synapse back into axon terminal.

Neurotransmitters

• Chemical messengers of nervous system.
  • Acetylcholine: muscle action and memory.
  • Beta-endorphin: pain and pleasure.
  • Dopamine: mood, sleep, and learning.
  • Norepinephrine: Heart, intestines, and alertness.
  • Serotonin: mood and sleep.

Drugs

• Psychotropic medication: restore neurotransmitter balance for psychiatric symptoms.
  • Agonist: Mimics/strengthens neurotransmitter effects.
  • Antagonist: Blocks/impedes neurotransmitter activity.
  • Example: Dopamine agonists for Parkinson’s, dopamine antagonists for schizophrenia.

Parts of the Nervous System

• Central Nervous System (CNS).
• Peripheral Nervous System (PNS).

The Peripheral Nervous System

1. Somatic nervous system: Relays sensory and motor information to/from CNS.
2. Autonomic nervous system: Controls internal organs and glands.
   • Sympathetic nervous system: Stress-related activities (fight or flight).
   • Parasympathetic nervous system: Routine operations (rest and restore).

The Brain and Spinal Cord

• Brain: Interconnected neurons and glia.
• Spinal Cord: Delivers messages to/from brain, has reflexes.

The Two Hemispheres

• Lateralization: Each hemisphere has specialized functions.
  • Left hemisphere: Controls right side of body.
  • Right hemisphere: Controls left side of body.

Forebrain, Midbrain, & Hindbrain

• Main brain categories.

Forebrain Structures

• Cerebral cortex
• Thalamus
• Hypothalamus
• Pituitary gland
• Limbic system

Cerebral Cortex: Lobes of the Brain

• Cerebral cortex: Highest mental capabilities.

The Frontal Lobe

• Involved in executive functions, motor control, emotion, and language.
  • Motor cortex
  • Prefrontal cortex
  • Broca’s area

The Parietal Lobe

• Processing sensory and perceptual information.
  • Somatosensory cortex.

The Temporal Lobe

• Associated with hearing, memory, emotion, and language.
  • Auditory cortex
  • Wernicke’s area.

The Occipital Lobe

• Associated with visual processing.

The Thalamus

• Relay center for senses (except smell).

The Limbic System

• Mediating emotional response and memory.
  • Amygdala
  • Hippocampus
  • Hypothalamus

The Midbrain

• Reticular formation
• Substantia Nigra
• Ventral tegmental area (VTA)

The Hindbrain

• Medulla
• Pons
• Cerebellum

Brain Imaging Techniques

• Radiation: CT, PET.
• Magnetic Fields: MRI, fMRI.
• Electrical Activity: EEG.

Computerized Tomography (CT) Scan

• Uses x-rays.

Positron Emission Tomography (PET) Scan

• Monitors blood flow changes using radioactive substance.

MRI and fMRI

• MRI: Magnetic fields to image tissue.
• fMRI: MRI showing metabolic activity changes over time.

Electroencephalography (EEG)

• Records electrical activity via scalp electrodes.

The Endocrine System

• Glands producing hormones to regulate body functions.
  • Hypothalamus
  • Pituitary gland
  • Thyroid
  • Adrenal gland
  • Gonad
  • Pancreas

Major Neurotransmitters and Their Effects

• Acetylcholine: Increased arousal.
• Beta-endorphin: Decreased anxiety.
• Dopamine: Increased pleasure.
• GABA: Decreased anxiety.
• Glutamate: Increased learning.
• Norepinephrine: Increased arousal.
• Serotonin: Modulated mood.