Psychology - The Biological Perspective

The Biological Perspective

Biological Bases and Biopsychology

  • Biopsychology: A branch of psychology focused on the biological bases of human behavior, thoughts, and feelings.

The Nervous System

  • A complex biological structure that regulates and controls all bodily processes.
  • Two main parts:
    • Central Nervous System (CNS): The brain and spinal cord; the command center of the body, made up of neurons.
    • Peripheral Nervous System (PNS): Controls body movement and is made up of nerves.

Peripheral Nervous System (PNS)

  • Controls body movement.
  • Made up of nerves.
  • Two systems:
    • Somatic System: Under conscious control, consisting of nerves that carry information from the senses to the CNS and from the CNS to the voluntary muscles.
      • Sensory Pathway: Nerves from sensory organs to the CNS, consisting of sensory neurons.
      • Motor Pathway: Nerves from the CNS to voluntary muscles, consisting of motor neurons.
    • Autonomic Nervous System: Not under conscious control; controls involuntary muscles, organs, and glands.
      • Sensory pathway nerves coming from the sensory organs to the CNS consisting of sensory neurons
      • Examples: heartbeat, sweat, digestion, breathing.
      • Operates under two modes/systems:
        • Sympathetic: Uses energy; active during flight-or-fight responses and bodily arousal.
        • Parasympathetic: Conserves energy; restores the body to normal conditions after arousal and responsible for day-to-day functioning of organs and glands.

Overview of Nervous System

  • Nervous System: An extensive network of specialized cells that carry information to and from all parts of the body.
  • Neuroscience: The study of the structure and function of neurons, nerves, and nervous tissue, and their relationship to behavior and learning.

Structure of the Neuron

  • Neurons: Specialized cells that communicate information within the nervous system.
    • Over 100 billion neurons in the human body, forming a communication network.
    • Three types of neurons:
      • Afferent Neurons: Carry messages from the senses (e.g., sight, sound) to the spinal cord.
      • Efferent Neurons (Motor Neurons): Carry messages from the spinal cord to the muscles.
      • Interneurons: Found in the center of the spinal cord; receive information from sensory neurons and send commands to the muscles through motor neurons; make up the bulk of neurons in the brain.

Parts of a Neuron

  • Dendrites: Branch-like structures that receive messages from other neurons.
  • Soma: The cell body of the neuron, responsible for maintaining the life of the cell.
  • Axon: Long, tube-like structure that carries the neural message to other cells.

Other Types of Brain Cells

  • Glial Cells
    • Grey fatty cells that:
    • Provide scaffolding to guide the growth of developing neurons and support mature neurons.
    • Wrap around neurons to form insulation to prevent interference from other electrical signals.
    • Release chemicals that influence a neuron’s growth and function.
  • Myelin Sheath: Fatty substances produced by certain glial cells that coat the axons of neurons to insulate, protect, and speed up the neural impulse.

Neurons in the Body

  • Nerves: Bundles of axons in the body that travel together through the body.

Neuron Communication

  • Sending messages to other cells involves:
    • Axon Terminals: Branches at the end of the axon.
    • Synaptic Knob: Rounded areas on the end of axon terminals.
    • Synaptic Vesicles: Sack-like structures inside the axon terminal containing chemicals.
    • Neurotransmitter: A chemical found in synaptic vesicles which, when released, has an effect on the next cell.
    • Synaptic Gap: Microscopic fluid-filled space between the rounded areas on the end of the axon terminals of one cell and the dendrites or surface of the next cell.
    • Receptor Sites: Holes in the surface of dendrites or certain cells of the muscles and glands shaped to fit only certain neurotransmitters.

How a Neuron Passes on a Message

  1. The neuron is at "resting potential" (negative charge of -70mv) – not firing a neural impulse.
  2. Neuron receives +ve charges from other neurons through the dendrites – these charges travel to the cell body.
  3. If there are enough +ve charges to exceed the “threshold” (passing mark) – then, the cell body generates an “action potential” (the cell FIRES).
  4. The action potential (like an electrical wave) travels down the axon and arrives at the axon terminal buttons.
  5. Synapse - The axon terminal buttons release “neurotransmitters” which link up with the dendrites of other neurons
  6. The whole process starts again.

Neurotransmitters

  • Chemical messengers that enable communication between nerve cells (neurons) and other cells in the body.
  • Roles of neurotransmitters (Class Activity):
    • Dopamine
    • Serotonin
    • Acetylcholine
    • Norepinephrine
    • Endorphins

Brain (CNS)

  • Neuropsychologist: A psychologist interested in how the brain determines human behavior, thoughts, and feelings.
  • Localization of Functions: The idea that different parts of the brain have different functions.
  • Nerves: Groups of axons bundled together that travel through the body.

Cerebral Hemispheres

  • Cerebral Hemispheres: The two sections of the cortex on the left and right sides of the brain.
  • Corpus Callosum: A thick band of neurons that connects the right and left cerebral hemispheres.

Lobes of the Brain

  • Frontal Lobe: Responsible for higher mental processes, decision making, planning, personality, memory storage, and the production of fluent speech.
  • Parietal Lobe: Contains the centers for touch, taste, and temperature sensations.
  • Occipital Lobe: Processes visual information from the eyes and identifies and makes sense of visual information.
  • Temporal Lobe: Responsible for the sense of hearing and meaningful speech, processes auditory information from the ears, and identifies and makes sense of auditory information.

Split-Brain Research

  • Study of patients with a severed corpus callosum.
  • Involves sending messages to only one side of the brain.
  • Demonstrates right- and left-brain specialization.

Results of Split-Brain Research

  • Left Side of the Brain: Controls language, writing, logical thought and analysis, mathematical abilities, processes information sequentially, and enables speech.
  • Right Side of the Brain: Controls emotional expression, spatial perception, recognition of faces, patterns, melodies, and emotions; processes information globally and cannot influence speech.

People with Brain Injury

  • Accidents, strokes.
  • Phineas Gage case (1848).
  • J.Z. (1992), 33 y.o.
  • Affected areas of life.

Phineas Gage Case (1848)

  • An explosion occurred while packing blasting powder into a rock, shooting a rod completely through his left frontal lobe.
  • He regained consciousness immediately and was able to talk and walk with assistance.
  • Before the accident: polite & hardworking, foreman for railroad
  • No impairments: speech, motor skills, learning, memory, IQ
  • After the accident: irritable, publicly profane, maths reasoning, problems with language (reading, writing, speaking)

J.Z. Case (1992)

  • Another case 150 years later, described by psychologists Meyers (1992).
  • J.Z., a 33-year-old, had surgery to remove a tumor from the same area as Gage.
  • Before surgery: honest, stable, reliable worker & husband
  • After surgery: irritable, dishonest, irresponsible, grandiose