Unit 1 Biological Basis of Behavior Slides

Unit 1: Biological Basis of Behavior

Part 1: Nature vs Nurture

  • Discussion of whether human behavior is influenced more by genetics or environment.

Evolutionary Psychology

  • Explores human similarities due to shared biology and evolutionary history.

  • Examines differences stemming from varying genes and environments.

  • Questions if gender differences are biologically predisposed or socially constructed.

  • Nature and nurture are seen as complementary, working together.

Molecular Genetics

  • Focuses on gene structure and function at a molecular level.

  • Studies heredity; genes can influence behaviors that affect survival.

  • Example: Genetic predisposition in prehistoric women to avoid bitter foods improving pregnancy success.

Epigenetics

  • Studies changes in organisms from gene expression modifications rather than changes in the DNA sequence.

  • Investigates how genes can be turned on or off through chemical reactions.

Heritability

  • Definition: The percentage of variance in a trait attributed to genetic differences.

  • Utilizes statistical analysis to determine differences among individuals in a population.

  • Examples of heritability percentages:

    • Creativity in teens: 25%

    • Extraversion in adults: 30%-50%

    • Autism in general population: 90%-95%

Types of Twins

  • Identical Twins (Monozygotic): Develop from a single fertilized egg that splits into two, sharing identical genes.

  • Fraternal Twins (Dizygotic): Develop from two separate eggs fertilized by two different sperm; genetically similar as any other siblings.

Part 2: The Nervous Systems & Neurons

Overview of the Nervous System

  • Central to human experience; processes information from the environment.

Central Nervous System (CNS)

  • Comprises the brain and spinal cord; weighs about 3 lbs.

  • Integrated network of interneurons responsible for processing and directing actions.

  • Communicates with the body's sensory receptors via the Peripheral Nervous System (PNS).

Peripheral Nervous System (PNS)

  • Made up of all nerves outside the CNS; facilitates communication to/from the CNS.

  • Divided into:

    • Somatic Nervous System: Controls voluntary movements.

    • Autonomic Nervous System (ANS): Manages involuntary functions (breathing, heartbeat).

Autonomic Nervous System Components

  • Sympathetic Nervous System: Activates fight or flight responses in dangerous situations, raising heart rate and respiration.

  • Parasympathetic Nervous System: Calms body after stress, promotes rest and digest functions.

  • Enteric Nervous System: Controls gastrointestinal functions, operates independently from the CNS.

The Neuron and Neural Firing

  • Neurons connect and communicate to form the brain's functional network.

  • Types of Neurons:

    • Sensory Neurons (Afferent): Carry sensory info to the CNS.

    • Motor Neurons (Efferent): Transmit commands from the CNS to the muscles.

    • Interneurons: Connect sensory and motor neurons, processing information in the CNS.

  • Neural impulses are electrical within a neuron and chemical between neurons.

  • Action Potential: Neural firing results from the influx of ions once a threshold is reached.

  • Resting Potential: The neuron's inactive state before firing, approximately -70 mV.

  • All or None Law: A neuron either fires (action potential) or does not; there’s no intermediate response.

Glial Cells

  • Support and protect neurons, assist in learning and memory.

Neurotransmitters

  • Chemical messengers that cross synapses, influencing behaviors and mental processes.

  • Key neurotransmitters:

    • Acetylcholine (ACh): Involved in learning and memory.

    • Endorphins: Natural pain relief and mood regulators.

    • Agonists: Increase neurotransmitter actions; Antagonists: Block neurotransmitter actions.

Endocrine System

  • Controls hormone secretion into the bloodstream.

  • Key glands:

    • Hypothalamus/Pituitary: Master control of hormonal functions.

    • Adrenal Glands: Produce stress hormones (adrenaline, cortisol).

  • Hormones affecting hunger:

    • Ghrelin: Stimulates appetite.

    • Leptin: Signals satiety.

Psychoactive Drugs

  • Chemical substances impacting brain function, consciousness, and mood.

  • Dependence: Physical or psychological reliance on drugs, leading to tolerance and withdrawal symptoms.

  • Types:

    • Depressants: Calm neural activity (alcohol, opioids).

    • Stimulants: Increase neural activity (caffeine, cocaine).

    • Hallucinogens: Cause altered perceptions (LSD, marijuana).

Part 3: The Brain

Biological Psychology

  • Studies interactions between biological and psychological processes.

Neuroplasticity

  • The brain’s adaptive ability to change through experience.

  • Lesions: Brain damage that can lead to compensatory adaptation.

Brain Scanning Techniques

  • Types include CT, MRI, EEG, MEG, PET, and fMRI, each with unique capabilities to image brain structure and function.

Brain Regions and Structures

  • Hindbrain: Manages essential survival functions.

  • Midbrain: Connects sensory information and motor movement.

  • Forebrain: Responsible for complex cognitive activities.

The Limbic System

  • Key for emotional regulation and memory formation (thalamus, hypothalamus, amygdala, hippocampus).

  • Hippocampus: Crucial for memory organization.

  • Amygdala: Central to emotional responses, particularly fear and aggression.

  • Hypothalamus: Regulates homeostasis and governs endocrine functions.

Cerebral Cortex

  • The brain's outer layer involved in higher cognitive processes and sensory perceptions.

  • Divided into lobes: Frontal (executive functions), Parietal (sensory input), Occipital (visual processing), Temporal (auditory processing).

Brain Hemispheres

  • Divided into left (language, logic) and right (perceptual tasks).

  • Split-brain patients: Show distinct functional differences when the corpus callosum is severed, affecting communication between hemispheres.