Brain and neuropsychology — AQA GCSE Psychology

The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS comprises the brain and spinal cord; it processes information and coordinates responses. The PNS carries messages to and from the CNS and links it to the body. The PNS divides into the somatic nervous system, which controls voluntary skeletal muscle movement, and the autonomic nervous system, which controls involuntary functions such as heart rate and digestion. The autonomic system further splits into the sympathetic branch, which prepares the body for action (for example raising heart rate), and the parasympathetic branch, which calms the body and restores balance. A multiple-choice question may ask which division performs a stated function.

The human nervous system is a communication network that collects information and coordinates responses. It divides into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is the brain and spinal cord: the brain processes information and generates responses, while the spinal cord carries messages between the brain and the body and coordinates some reflex actions. The PNS is all the nerves outside the CNS and links the CNS to the body. It splits into the somatic and autonomic divisions. The somatic division carries sensory information to the CNS and motor commands to skeletal muscles, producing voluntary movement. The autonomic division controls involuntary, automatic functions such as heart rate, digestion and breathing, and it divides further into the sympathetic and parasympathetic branches.

The autonomic nervous system controls involuntary body functions and has two branches. The sympathetic branch activates the fight or flight response when a threat is perceived: it increases heart rate and breathing rate, dilates the pupils, diverts blood to muscles and triggers adrenaline release, preparing the body to confront or escape danger. The parasympathetic branch then restores calm, slowing heart rate and aiding digestion. The James-Lange theory of emotion proposes that an event first produces a physiological response, and the brain interprets that bodily change as an emotion. So we do not tremble because we are afraid; rather, we interpret our trembling as fear. The sequence is stimulus, then physiological arousal, then interpretation, then the felt emotion.

A neuron has a cell body, dendrites that receive signals, and an axon carrying an electrical impulse away, often wrapped in a myelin sheath that speeds conduction; axon terminals meet the next cell at a synapse. Sensory neurons carry impulses from receptors inward, relay neurons connect neurons within the central nervous system, and motor neurons carry impulses outward to effectors such as muscles. At the synapse, an impulse triggers release of neurotransmitters across the gap; they bind receptors on the next neuron and are then reuptaken by the presynaptic neuron. Some transmitters excite the next neuron, making firing more likely; others inhibit it, making firing less likely. The summed balance of excitation and inhibition determines whether the next neuron fires, so the three neuron types and both synaptic processes interact to shape behaviour.

Hebb proposed that learning occurs because neurons that fire together repeatedly strengthen their connection. When one neuron repeatedly stimulates another, changes at the synapse make that link more efficient, so the same input is more likely to trigger the same response. Hebb described this as cells that fire together wiring together: repeated co-activation produces neuronal growth, meaning stronger synaptic connections rather than new whole neurons. The strengthened pathway is the physical basis of a learned association, which is why practice makes a response more reliable. For example, repeatedly practising a skill strengthens the neural pathway involved, so the skill becomes easier and more automatic over time.

The brain is studied as a set of named regions, each with a characteristic position and a main job. The frontal lobe sits at the front, behind the forehead, and is linked to movement, decision-making and planning. The temporal lobe lies at the side, above the ear, and is linked to hearing and memory. The parietal lobe sits at the top and back of the head and is linked to processing touch and spatial information. The occipital lobe is at the very back and is linked to vision. The cerebellum is the smaller, folded structure below the occipital lobe at the back of the head and is linked to balance, posture and smooth coordination of movement. Learn each name with its position and its main function, because multiple-choice questions often give a function and ask which structure performs it, or give a structure and ask which function fits.

Each named brain structure has a basic function you should be able to state and recognise. The frontal lobe is associated with movement, planning and decision-making. The temporal lobe is associated with hearing and memory. The parietal lobe is associated with processing touch and spatial information. The occipital lobe is associated with vision. The cerebellum is associated with balance, posture and smooth coordination of movement. In a multiple-choice question you may be given a scenario, such as a person struggling to keep balance, and asked which structure is most involved; you then match the described job to the correct structure. Keep functions basic and avoid over-claiming, because the specification asks for basic function rather than detailed anatomy.

Localisation means that particular functions are governed by particular regions of the cortex rather than the whole brain acting as one mass. The motor area, in the frontal lobe, sends commands that produce voluntary movement, mainly on the opposite side of the body. The somatosensory area, in the parietal lobe, receives touch, pressure, temperature and pain information, again largely from the opposite side. The visual area sits at the back of the brain in the occipital lobe and processes signals from the eyes. The auditory area in the temporal lobe handles sound. Language is mainly localised to the left hemisphere, with Broca's area linked to speech production and Wernicke's area to understanding language. Damage to a region therefore produces a fairly specific loss, which is the key evidence for localisation.

Penfield stimulated the exposed cortex of awake patients during brain surgery, using a weak electrical current while the patient reported what they experienced. When he stimulated parts of the temporal lobe, patients sometimes reported vivid, dream-like recollections or a sense that a familiar experience was happening again. Penfield called these regions the interpretive cortex because stimulation seemed to trigger the patient's own interpretation of experience, such as a memory with a sense of familiarity. The study is important because it links a specific brain area to particular experiences and supports localisation of function. It also raises ethical issues, since patients were awake and the procedure was invasive, and the findings rely on patients' verbal reports, which may be unreliable.

Cognitive neuroscience links the brain's physical structure to mental processes and observable behaviour. Structure means the parts themselves: the cerebral cortex with its lobes, the cerebellum and the brainstem. Function means what those parts do, such as the frontal lobes supporting planning and decision-making, the occipital lobes processing visual information and the cerebellum coordinating movement and balance. The key idea is that changes in structure or activity accompany changes in behaviour and cognition. For example, damage to a region after injury may be followed by a specific loss of ability, and a task that demands memory or attention produces measurable activity in particular areas. Cognitive neuroscience therefore combines biological evidence with psychological measures to explain why people behave and think as they do.

Brain scanning lets researchers identify functioning by observing the brain rather than guessing from behaviour alone. A CT (computerised tomography) scan uses X-rays to build images showing structure such as bones, tumours or damage, so it is useful for spotting injury but gives limited information about activity. A PET (positron emission tomography) scan uses a radioactive tracer to show which areas are using most glucose, indicating activity during a task. An fMRI (functional magnetic resonance imaging) scan uses magnetic fields to detect changes in blood oxygen, giving detailed images of activity with good spatial resolution. Each technique trades off detail, invasiveness and what it reveals, so the choice depends on whether structure or function is the focus.

Tulving's 'gold' study is a neuropsychological investigation of how the brain supports memory. Participants carried out memory tasks while their brain activity was recorded using a PET scan, which shows which brain areas are most active during a task. The key finding is that different kinds of memory draw on different brain regions: recalling personally experienced events (episodic memory) is linked to the frontal lobes, while remembering facts and general knowledge (semantic memory) is linked to the posterior regions. When answering a multiple-choice question, identify the imaging technique used (PET scan) and the brain areas associated with each memory type, then select the option that matches both.

Neurological damage happens when part of the brain or nervous system is harmed, for example by a stroke (when blood supply to part of the brain is cut off) or by a physical injury such as a blow to the head. Different areas of the brain control different functions, so the effects depend on which area is damaged. Damage to motor areas can affect movement: a person may have weakness, clumsiness, difficulty walking or problems controlling an arm or hand. Damage can also affect behaviour: a person may become more impulsive, have changes in mood, or find it harder to plan and control their actions. For this specification you need a basic understanding, so learn one or two examples of motor effects and one or two examples of behavioural effects, and be able to explain that the location of the damage matters.