What you'll learn
This topic explores the biological basis of behaviour through studying the structure and function of the brain and nervous system. You'll examine how different brain regions control specific functions, understand the role of neurons in transmitting information, and evaluate key neuropsychological research that demonstrates localisation of function in the brain.
Key terms and definitions
Neuron — a specialised nerve cell that transmits electrical impulses throughout the nervous system
Synapse — the microscopic gap between two neurons where neurotransmitters are released to pass signals from one neuron to another
Central Nervous System (CNS) — the brain and spinal cord, which process information and coordinate responses
Localisation of function — the principle that specific areas of the brain are responsible for specific behaviours or cognitive processes
Neurotransmitter — a chemical messenger released at synapses that transmits signals between neurons (e.g. serotonin, dopamine)
Brain scanning techniques — methods used to study brain structure and function, including fMRI and PET scans
Neuroplasticity — the brain's ability to reorganise itself by forming new neural connections throughout life
Cerebral cortex — the outer layer of the brain responsible for higher-level cognitive functions such as thinking, perceiving and language
Core concepts
Structure of the nervous system
The human nervous system divides into two main parts:
The Central Nervous System (CNS) consists of:
- The brain — controls most body functions and processes sensory information
- The spinal cord — relays information between the brain and the rest of the body
The Peripheral Nervous System (PNS) consists of:
- All nerves outside the CNS
- Connects the CNS to limbs and organs
- Further divides into somatic (voluntary) and autonomic (involuntary) systems
The nervous system coordinates responses to internal and external stimuli through rapid electrical and chemical signalling.
Neuron structure and function
Neurons are the fundamental units of the nervous system. Each neuron has three main parts:
Dendrites receive signals from other neurons. These branch-like structures extend from the cell body and contain receptor sites for neurotransmitters.
Cell body (soma) contains the nucleus and maintains the cell's metabolic functions.
Axon is a long fibre that carries electrical impulses away from the cell body toward other neurons. Many axons are covered with a myelin sheath — a fatty insulating layer that speeds up transmission.
Terminal buttons at the axon's end release neurotransmitters into the synapse.
There are three types of neurons:
- Sensory neurons carry information from sensory receptors to the CNS
- Motor neurons carry instructions from the CNS to muscles and glands
- Relay neurons connect sensory and motor neurons within the CNS
Synaptic transmission
Communication between neurons occurs at synapses through a chemical process:
- An electrical impulse travels down the axon to the terminal buttons
- This triggers the release of neurotransmitters from vesicles into the synaptic gap
- Neurotransmitters diffuse across the synapse (approximately 20-40 nanometres wide)
- They bind to receptor sites on the dendrites of the next neuron
- This may trigger a new electrical impulse in the receiving neuron
- Remaining neurotransmitters are either broken down by enzymes or reabsorbed (reuptake)
This process occurs in milliseconds and allows for precise control of behaviour and cognition.
Brain structure and localisation of function
The brain consists of several distinct regions, each responsible for different functions:
The cerebrum is the largest part, divided into two hemispheres (left and right). Each hemisphere controls the opposite side of the body. The cerebral cortex covers the cerebrum and is responsible for conscious thought, memory, and language.
The cerebellum (Latin for "little brain") sits at the back of the brain and coordinates:
- Balance and posture
- Fine motor movements
- Motor learning (e.g. learning to ride a bicycle)
The brain stem connects the brain to the spinal cord and controls:
- Breathing
- Heart rate
- Sleep/wake cycles
- Other automatic functions essential for survival
The limbic system includes structures involved in emotion and memory:
- The hippocampus processes new memories and spatial navigation
- The amygdala processes emotions, particularly fear and aggression
Cortical specialisation
The cerebral cortex is divided into four lobes in each hemisphere:
Frontal lobe functions:
- Planning and decision-making
- Personality and social behaviour
- Motor control (primary motor cortex)
- Speech production (Broca's area in the left hemisphere)
Parietal lobe functions:
- Processing sensory information from the body
- Spatial awareness and navigation
Temporal lobe functions:
- Processing auditory information
- Language comprehension (Wernicke's area in the left hemisphere)
- Memory formation
Occipital lobe functions:
- Processing visual information
- Contains the primary visual cortex
This demonstrates clear localisation of function, though many complex behaviours require coordination across multiple brain regions.
Key neuropsychology studies
Phineas Gage (1848)
Phineas Gage was a railway construction foreman who survived an accident where an iron rod passed through his frontal lobe. Following the injury:
- His personality changed dramatically
- He became impulsive, aggressive, and unable to plan
- His language and memory remained intact
This case study provided early evidence that the frontal lobe controls personality and executive functions. However, limitations include reliance on subjective reports and inability to precisely identify damaged areas.
HM (Henry Molaison, 1953)
HM underwent surgery to treat severe epilepsy, which removed parts of both temporal lobes including most of his hippocampus. The results showed:
- Severe anterograde amnesia — inability to form new long-term memories
- Intact short-term memory (could hold conversations)
- Preserved procedural memory (could learn new motor skills)
- Memories from before surgery largely intact
This demonstrated the hippocampus's crucial role in forming new declarative memories but showed procedural memory involves different brain areas.
Brain scanning techniques
Modern neuroscience uses sophisticated scanning methods:
fMRI (functional Magnetic Resonance Imaging) detects changes in blood oxygen levels, showing which brain areas are active during specific tasks. Strengths include high spatial resolution and non-invasive nature. Limitations include poor temporal resolution (activity averaged over seconds) and high cost.
PET (Positron Emission Tomography) scans use radioactive tracers to show brain activity and can measure neurotransmitter activity. It's useful for studying brain function but involves radiation exposure.
These techniques have revolutionised neuropsychology by allowing researchers to study living brains during different activities.
Worked examples
Example 1: Short answer question (3 marks)
Question: Explain what is meant by 'localisation of function' in the brain.
Mark scheme answer:
Localisation of function refers to the principle that specific areas/regions of the brain are responsible for specific behaviours or cognitive processes (1 mark). For example, the motor cortex in the frontal lobe controls voluntary movement (1 mark), while Broca's area in the left frontal lobe is responsible for speech production (1 mark).
Examiner note: Define the term clearly first, then provide specific examples with named brain regions and their functions.
Example 2: Research methods question (4 marks)
Question: Describe how brain scanning techniques have contributed to our understanding of brain function.
Mark scheme answer:
Brain scanning techniques such as fMRI allow researchers to observe which brain areas become active during specific tasks (1 mark). For example, fMRI scans show increased activity in the motor cortex when participants move their fingers (1 mark). This provides objective evidence for localisation of function in living brains (1 mark), confirming findings from case studies like Phineas Gage but with greater precision and the ability to study healthy participants (1 mark).
Examiner note: Name specific techniques, explain how they work, give concrete examples, and link to theoretical concepts.
Example 3: Extended response question (6 marks)
Question: Evaluate the case study of HM as evidence for localisation of function. Refer to both strengths and weaknesses in your answer.
Mark scheme answer:
Strengths: HM's case provided strong evidence that the hippocampus is specifically involved in forming new long-term memories, as his amnesia appeared immediately after hippocampal removal (2 marks). The case was studied extensively over 50 years, providing detailed longitudinal data about memory processes and showing his deficits were permanent, supporting the hippocampus's crucial role (1 mark).
Weaknesses: As a case study of one individual, findings cannot be generalised to the wider population — HM may have been unique (1 mark). The surgery was imprecise by modern standards, making it difficult to identify exactly which structures were damaged, limiting conclusions about specific brain regions (1 mark). The study raises ethical concerns as HM could not give informed consent for all subsequent research due to his memory impairment (1 mark).
Examiner note: Extended responses require balanced evaluation. Present strengths and weaknesses separately, using psychological terminology and linking evidence explicitly to the question.
Common mistakes and how to avoid them
Confusing structure with function — Don't just list brain parts; always explain what each area does. For example, don't write "The cerebellum is at the back of the brain" without adding "and coordinates balance and motor control."
Mixing up neuron types — Remember: sensory neurons carry information TO the CNS, motor neurons carry instructions FROM the CNS. Think "sensory in, motor out."
Oversimplifying localisation — Avoid stating that single brain areas work completely alone. Many functions require coordination between multiple regions. Use phrases like "primarily responsible for" rather than "controls."
Forgetting evaluation in extended answers — Questions worth 6+ marks always require evaluation. Prepare strengths and limitations for every study or concept you learn.
Misunderstanding synaptic transmission — Remember the sequence: electrical → chemical → electrical. The impulse travels electrically along the axon, becomes chemical at the synapse, then electrical again in the next neuron.
Writing vague descriptions of case studies — Always include: the participant's name/identifier, what happened to them, specific findings, and what this tells us about brain function. Generic answers score poorly.
Exam technique for "Brain and Neuropsychology"
Command words matter: "Describe" requires factual information without judgment (e.g. what happened in a study). "Explain" needs you to show why/how something occurs. "Evaluate" demands analysis of strengths and weaknesses with clear judgments.
Use the mark allocation strategically: For 3-mark questions, make three distinct points. For 6-mark questions, structure your answer with approximately 4 marks of description/application and 2 marks of evaluation, or 3 marks each of strengths and weaknesses.
Name specific brain regions and structures — The examiner wants precise terminology. Write "frontal lobe" not "front of brain," "hippocampus" not "memory area." This demonstrates detailed knowledge worth higher marks.
Connect case studies to concepts — When discussing Phineas Gage or HM, explicitly link their symptoms to localisation of function. Don't just describe what happened; explain what it demonstrates about how the brain works.
Quick revision summary
The nervous system divides into the CNS (brain and spinal cord) and PNS. Neurons transmit information through electrical impulses and chemical neurotransmitters at synapses. The brain shows localisation of function: different regions (frontal, parietal, temporal, occipital lobes, cerebellum, brain stem) control specific behaviours. Case studies like Phineas Gage and HM demonstrate how brain damage affects specific functions, while modern fMRI and PET scans allow non-invasive study of brain activity. Understanding brain structure and function explains the biological basis of behaviour and cognition.