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Biological Bases of Behaviour

Biological Bases of Behaviour

Introduction

  • Referenced by Matthew Sorley at Carleton University.

  • Recognizes the brain's significance with various quotes:

    • "Our 3-lb universe" (Hooper & Teresi)

    • "The soul’s frail dwelling house" (Shakespeare)

    • "The activity of the brain gives rise to the contents of the mind" (Levitin).

Neuropsychology

  • A field that studies brain behavior relationships.

Key Questions in Neuropsychology

  • How are thoughts, feelings, and behaviors represented in the brain?

  • How is the nervous system organized?

  • What are the various brain structures, and what are their functions?

  • How do we assess brain function?

  • How does learning and experience alter the brain’s circuits?

  • In what ways is our brain adaptable?

Neurons

Overview of Neurons

  • Neuron: The basic unit of the nervous system, responsible for transmitting information throughout the body.

Components of a Neuron

  • Dendrites: Receive signals from other neurons.

  • Cell body (Soma): Contains the nucleus and organelles, maintaining the cell's health.

  • Axon: Transmits electrical impulses away from the cell body.

  • Axon terminals: Release neurotransmitters to communicate with other neurons.

  • Myelin sheath: Insulates the axon, speeding up transmission of the neural impulse.

  • Nodes of Ranvier: Gaps in the myelin sheath where ion exchange occurs, facilitating rapid conduction of impulses.

Neural Impulse: The Electrochemical Process

  1. Resting State:

    • Neuron is negatively charged inside relative to outside (approx -70mV).

  2. Depolarization:

    • Stimulus causes positively charged ions to flow into the neuron, resulting in action potential.

  3. Repolarization:

    • Positively charged ions flow out, returning to polarized state.

  4. Resting Potential Restoration:

    • The neuron returns to its initial resting state.

Action Potential Characteristics

  • All-or-None Principle: Once an action potential is initiated, it travels down the axon fully or not at all.

  • Voltage Levels:

    • Resting potential: -70 mV

    • Action potential peak: +40 mV

    • Potassium ions flow out during repolarization process.

Synapse and Neurotransmitters

  • Synapse: The junction between two neurons where communication occurs.

    • Components: Synaptic cleft, synaptic vesicles, receptors.

  • Neurotransmitters: Chemical messengers that can be excitatory or inhibitory, influencing the likelihood of the postsynaptic neuron firing.

    • Examples include:

    • Acetylcholine (ACh): Important for muscle activation and memory.

    • Dopamine: Involved in reward, motivation, and movement regulation.

    • Serotonin: Affects mood, anxiety, and happiness levels.

    • Norepinephrine: Influences attention, responding actions, and the fight-or-flight response.

    • GABA: The main inhibitory neurotransmitter, helping to calm neural activity.

    • Glutamate: The main excitatory neurotransmitter, essential for synaptic plasticity.

    • Endorphins: Natural painkillers that can create sensations of pleasure.

Nervous System

  • Central Nervous System (CNS): Comprises the brain and spinal cord.

  • Peripheral Nervous System (PNS): Connects the CNS to the rest of the body.

    • Subdivided into Somatic and Autonomic Nervous Systems.

Spinal Cord Anatomy

  • Composed of segments connected to different parts of the body:

    • Cervical Nerves: Control neck and arm functions.

    • Thoracic Nerves: Control trunk and abdominal functions.

    • Lumbar Nerves: Responsible for leg movements.

    • Sacral Nerves: Control bowel, bladder, and sexual functions.

Reflex Actions

  1. Stimulus: A hot stove triggers pain receptors in hand.

  2. Afferent Neurons: Carry signals to the spinal cord.

  3. Reflex Action Initiation: Involves a fast, automatic response to pull the hand away without needing a brain signal immediately.

  4. Efferent Neurons: Carry signals from the spinal cord to muscles for response.

Brain Structures and Their Functions

  • Brain Stem: Controls survival functions (heart rate, breathing).

  • Cerebral Cortex: Involved in higher-level cognitive functions.

  • Cerebellum: Coordinates voluntary movement and balance.

  • Forebrain Structures:

    • Hypothalamus: Regulates body functions and behaviors like hunger, thirst, temperature control.

    • Amygdala: Plays a key role in emotion processing.

    • Basal Ganglia: Involved in movement and reward.

    • Thalamus: Acts as a sensory gateway, relaying information to the cortex.

    • Hippocampus: Critical for memory formation.

Brain Adaptation

  • The concept of neural plasticity: The brain's ability to change and adapt as a result of experience.

  • Importance of learning and exposure to enriching environments for brain development and synaptic growth.

  • Hebbian plasticity: Principles that underline how connections between neurons strengthen with repeated activity.

The Power of Conversation

  • Family conversations have a magical influence on children’s brain development, indicated by correlations between conversation frequency and children's language skills.

Recovery from Damage

  • Neurogenesis: The process where new neurons are generated in areas of the cerebral cortex, particularly noted in recovery from brain injury.

  • Ethical Issues: Arise concerning the use of stem cells in research and treatments.

Course Information

  • PSYC 2307: Human Neuropsychology I - Overview including basic anatomy, physiology, and brain-behavior relationships.

    • Prerequisites: PSYC 1001, 1002.

  • PSYC 3307: Human Neuropsychology II - Focused on cortical metabolism, neuropsychological testing, and research methods.

    • Prerequisite: PSYC 2307 and not eligible if PSYC 3207 was taken.