Development of Brain Structures & Functions (OCR GCSE Psychology): Revision Note

The nervous system

• The nervous system acts as the body’s control centre by:

  • interpreting sensory information from the environment

  • sending messages to the body about how to respond

• It is made up of the central nervous system (CNS) and the peripheral nervous system (PNS).

  • The CNS includes the brain and spinal cord, which process and coordinate all information

  • The PNS connects the CNS to the rest of the body through a network of nerves

• The nervous system is made up of neurons (groups of neuron cells make up a nerve) that transmit messages in the form of electrical impulses. Each neuron consists of:

  • a cell body: contains the nucleus

  • dendrites: receive information/the signal

  • an axon: sends messages away from the cell body

• Messages travel across the small gap between neurons called the synapse using neurotransmitters, which are chemical messengers

• The receptors on the receiving neuron are shaped to fit specific neurotransmitters, ensuring accurate communication between cells

Stages of brain development

Pre-natal (before birth)

• Brain development begins around 16 days after fertilisation when the neural tube forms

  • By 3 weeks, the fore-, mid- and hindbrain fuse together

  • By 8 weeks, the neural tube has developed into the brain and spinal cord

  • Between 6 and 20 weeks, new brain cells (neurons) form rapidly

  • These neurons migrate to their correct locations, forming key brain regions, including the cerebral cortex, which controls thought, intelligence, and movement

  • By 5 months, connections called synapses begin to form, allowing neurons to communicate

  • The foetus can respond to sound by the second trimester, and brain growth continues until birth

  • By the time a baby is born, there are already 100 billion neurons in place

Factors affecting prenatal brain development

• Exposure to substances such as alcohol can disrupt neural connections and lead to Foetal Alcohol Syndrome

  • This can cause learning and memory problems after birth

Childhood

• After birth, the brain continues to grow rapidly, forming around 1000 new neural connections per second

  • By age four, the number of synapses in some areas (e.g. visual cortex) nearly doubles compared to adulthood

  • The prefrontal cortex, which helps with decision-making and memory, is particularly active, allowing children to understand cause and effect

  • During later childhood, unnecessary neural connections are ‘pruned’, making the brain more efficient

Adolescence

• During adolescence, major changes occur in the grey matter found on the surface of the brain

  • The limbic system (linked to emotion and memory) matures before the prefrontal cortex, which is responsible for decision-making and impulse control

    • This delay explains why teenagers are often more emotional and risk-taking compared to other stages of their lives

  • The frontal lobe continues to develop; it reaches maturity around age 16

Adulthood

• By around age 25, the prefrontal cortex fully matures, improving rational decision-making and reducing impulsivity

  • In later adulthood, brain function may decline due to the loss of neurons

  • Neurodegenerative diseases such as Alzheimer’s and Parkinson’s can cause memory loss, impaired thinking, and reduced motor control