VCE Psychology Unit 1 (AOS 2) - Brain and Behaviour

Role of the Brain in Mental Processes and Behaviour

Overview of the Brain

Learning Intention

To understand the brain’s anatomy and how the understanding of the brain's role has changed over time.

Success Criteria

Explain the Brain vs. Heart debate and the Mind-Body problem.

Glossary Terms

  • Grey matter

  • White matter

  • Brain vs heart debate

  • Mind-body problem

  • Monism

  • Dualism

The Complexity of the Brain

  • The brain contains approximately 86 billion neurons (nerve cells).

  • Each neuron connects to between 1,000 and 15,000 or more other neurons.

  • These connections create neural pathways for electrochemical energy/information to be sent throughout the body via the spinal cord.

Analogies for Understanding Brain Characteristics

  • Consistency: Avocado.

  • Size: Half a melon.

  • Texture: Walnut.

  • Weight: 1.5 kg Washing Powder.

  • Surface Area: 12 sheets of newspaper (if the brain were laid out flat).

Structures that Protect the Brain

  • Arteries: Carry nutrients and oxygen-rich blood; their absence leads to rapid tissue death.

  • Capillaries: Form the blood-brain barrier, restricting entry of harmful substances.

  • Cerebral Cortex: The outer layer of nerve tissue covering the cerebrum.

Protective Mechanisms

  • Encased in a bony skull.

  • Covered by three transparent membranes (meninges).

  • Cushioned by cerebrospinal fluid.

White & Grey Matter

Slicing the brain reveals inner features with both dark and light areas representing different parts.

  • Grey Matter: Primarily composed of nerve cell bodies and their local connections. The outer cerebral cortex is made of grey matter.

  • White Matter: Mostly nerve fibres connecting distant brain areas, coated with a fatty substance (myelin) that gives it a whitish appearance. Found beneath the cortex.

  • Ventricles: The brain has four ventricles. The two largest are wing-shaped cavities within the cerebrum which form an inner communication network, filled with cerebrospinal fluid.

Approaches to Understanding the Brain

  • Understanding of the brain's role and investigative techniques have evolved over time alongside technological advancements.

The Brain-Heart Debate

  • Brain-Heart Debate: Explores whether thoughts, feelings, and behaviours originate from the brain or heart; traced back to ancient Greek philosophers.

Brain Hypothesis (Alcmaeon, 475 BCE)

  • Mental processes are located in the brain.

  • Dissected animals and discovered the optic nerve connected eyes to the brain.

  • Proposed that all senses are connected to the brain, making the brain responsible for perceptions, thoughts, and mental processes.

Heart Hypothesis (Empedocles, 494–430 BCE & Aristotle, 384–322 BCE)

  • Mental processes occur in and around the heart.

  • Empedocles: The heart is the center of the body’s blood vessel system; perceptions form in the blood, and intelligence depends on blood composition.

  • Aristotle: The brain serves as a cooling mechanism to lower blood temperature.

Galen's Contribution (129–216 CE)

  • Observed that nerves from sense organs went to the brain, not the heart.

  • Brain injury adversely affected behaviour.

  • Gladiators with heart wounds retained reasoning powers until death, indicating the rational soul (mind) does not reside in the heart.

  • Worked as a physician to gladiators, treating head injuries and observing behavioral changes.

  • Galen argued for the brain hypothesis, which is now universally accepted due to overwhelming scientific evidence.

The Mind-Body Problem

  • Mind-Body Problem: Explores whether the mind and body are distinct entities or a single entity.

Definitions

  • Mind: A non-physical, spiritual entity (i.e., thoughts).

  • Body: The physical entity carrying out biological processes, including the brain.

Philosophical Views

  • Most Greek philosophers believed in monism, i.e., that the mind and body are the same.

  • Descartes (1596–1650) proposed dualism: the mind and body are separate but interconnected; they interact via the pineal gland.

  • Descartes believed the body could influence the mind, and vice versa, contributing to thoughts, sensations, and bodily emotions.