QCE Psychology - Unit 3 - Brain function

Nervous system and brain function

Build an accurate model of nervous-system organisation, reflex arcs, localisation, distributed processing, language, movement, emotion and plasticity.

Part of the free QCE Psychology notes library for Unit 3: Brain function.

Updated 2026-08-08 - 5 min read

QCAA official coverage - Psychology 2025 v1.3

Exact syllabus points covered

  1. Describe the structure of the human nervous system, with reference to the central (i.e. brain and spinal cord) and peripheral (i.e. somatic and autonomic) nervous systems.
  2. Describe the role of the spinal cord in the human nervous system, with reference to monosynaptic and polysynaptic spinal reflexes.
  3. Describe how brain function can be viewed as both localised and distributed, with some functions being identified with specific areas in the cerebral cortex, including the frontal, occipital, parietal and temporal lobes
  4. Describe how brain function can be viewed as both localised and distributed, with some functions being distributed across large or multiple brain regions, e.g.  the storage of explicit memory is associated with the hippocampus, the neo-cortex and the amygdala  the formation of implicit memories relies upon the basal ganglia and cerebellum.
  5. Explain that Broca’s area, Wernicke’s area, and Geschwind’s territory have specific roles in language processing.
  6. Explain the interaction of the primary motor cortex, cerebellum and basal ganglia in coordinating voluntary movement.
  7. Explain the importance of the limbic system and the prefrontal cortex for the experience of emotion.
  8. Consider how findings from behavioural neuroscience can be used by psychologists.
  9. Appreciate how plasticity assists in the recovery from brain injury.
  10. Recognise that all human behaviour has a biological basis.

Psychological explanations become stronger when they connect behaviour to a biological pathway without reducing a complex person to one brain area. This lesson builds that pathway from the whole nervous system to coordinated brain networks.

Nervous-system hierarchy and reflex pathway

Original Sylligence diagram for psychology nervous system reflex.

Nervous-system hierarchy and reflex pathway

Organise the nervous system before naming functions

The central nervous system (CNS) contains the brain and spinal cord. It integrates information and coordinates responses. The peripheral nervous system (PNS) connects the CNS with receptors, muscles, glands and organs.

The PNS includes:

| Division | Main role | Example | | --- | --- | --- | | Somatic | Voluntary skeletal movement and sensory information | Reaching for a cup | | Autonomic | Largely involuntary regulation of organs and glands | Changing heart rate | | Sympathetic branch | Mobilises resources during challenge | Increased heart rate and alertness | | Parasympathetic branch | Conserves resources and supports restoration | Slower heart rate after danger passes |

A high-quality response follows the route. A heat receptor detects a stimulus, a sensory neuron carries information toward the CNS, interneurons integrate it, and a motor neuron carries a command to an effector.

Reflexes show what the spinal cord can do

A monosynaptic reflex has one synapse between a sensory neuron and a motor neuron. The patellar reflex is the usual model: stretching the tendon activates a sensory neuron, which excites a motor neuron to contract the quadriceps.

A polysynaptic reflex includes one or more interneurons. In a withdrawal reflex, interneurons can excite flexor muscles and inhibit extensors while other pathways carry information to the brain. The response can begin before conscious pain perception, but the brain still receives and interprets the event.

Localised and distributed brain function

The four cortical lobes have useful broad associations:

  • frontal lobe: planning, inhibition, decision-making and voluntary motor control
  • parietal lobe: body sensation and spatial processing
  • temporal lobe: auditory processing, language-related processing and aspects of memory
  • occipital lobe: visual processing

These associations are not sealed boxes. Vision, language, movement, emotion and memory require connected systems.

Explicit memory formation and storage involves the hippocampus, neocortex and amygdala. The hippocampus supports consolidation and relational or contextual organisation; neocortical networks support long-term distributed representations; the amygdala strengthens memory for emotionally significant events. Implicit skill learning relies substantially on the basal ganglia and cerebellum.

Language, voluntary movement and emotion

Broca's area contributes to speech production and language planning. Wernicke's area contributes to language comprehension. Geschwind's territory helps integrate information across language-related regions. Damage can produce different patterns of aphasia, but normal language is a network achievement rather than a relay through three isolated boxes.

Voluntary movement also requires a division of labour:

  1. the primary motor cortex sends commands for voluntary movement
  2. the cerebellum compares intended and actual movement, supporting timing, coordination and error correction
  3. the basal ganglia help select and initiate appropriate movement patterns while suppressing competing actions

Emotion similarly emerges from interaction. The limbic system contributes to salience, motivation and emotional learning. The prefrontal cortex helps interpret context, regulate responses and choose actions. Strong emotion does not simply “switch off” the frontal lobe; regulation changes as networks compete and cooperate.

Worked example: localised damage, distributed consequence

Plasticity and recovery

Plasticity is the nervous system's capacity to change its connections and functional organisation. After injury, recovery can involve strengthening surviving pathways, recruitment of nearby or connected regions, practice-dependent reorganisation and compensatory strategies.

Plasticity does not guarantee complete recovery. Outcome depends on lesion size and location, age, time since injury, rehabilitation, health and the function being retrained. This is why behavioural neuroscience findings can guide assessment and rehabilitation without perfectly predicting one person's outcome.

Try it yourself

Common exam traps

  • listing CNS and PNS without showing their relationship
  • treating sympathetic as “bad” and parasympathetic as “good”
  • saying each lobe has only one function
  • calling a reflex voluntary because the person notices it
  • presenting localisation and distributed processing as mutually exclusive
  • using one behavioural symptom as definitive proof of one damaged structure

Sources

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