Choose what the brain is doing — seeing, hearing, moving, speaking, remembering — to light up the main areas involved and watch the signal travel. Real tasks use many areas at once; the sim shows the most important ones.
Click anywhere on the cortex to find out which lobe it is, or use the legend. The left hemisphere controls the right side of the body and the right hemisphere the left side. Turn on “Color the lobes” to see the borders.
The brain receives information from your senses, decides what it means, stores memories, and sends commands to your muscles and glands. Together with the spinal cord it forms the central nervous system. It is made of neurons, cells that send electrical and chemical signals, supported by even more glial cells.
The cerebrum is the large, folded upper part, split into left and right hemispheres joined by the corpus callosum. Its thin outer layer, the cerebral cortex, is divided into four lobes: frontal (planning and movement), parietal (touch and space), temporal (hearing, language and memory) and occipital (vision). Under the back of the cerebrum is the cerebellum (balance and coordination), and the brainstem connects everything to the spinal cord and keeps you breathing. Deep inside are the thalamus, hypothalamus and the limbic structures — hippocampus and amygdala — that handle relaying senses, body balance, memory and emotion.
Most pathways cross over, so the left hemisphere controls the right side of the body and sees the right half of the visual field. Some jobs lean to one side — language depends mostly on the left hemisphere in about $95\%$ of right-handed people and most left-handed people — but nearly every task uses networks spread across both hemispheres. The folds (gyri and sulci) pack a large cortex, about $0.2\,\mathrm{m^2}$, into the skull, and connections keep changing with learning (neuroplasticity) throughout life.
Turn on Color the lobes and click each colour. Press Moving: the signal starts in the left motor cortex to move the right hand. Press Seeing and follow the signal from the eyes to the back of the brain. Switch on See inside and press Fear or Remembering to find the amygdala and hippocampus hidden in the temporal lobes. Use the Top view to see the deep fissure between the hemispheres.
| Part | Where it is | Main functions |
|---|---|---|
| Frontal lobe | Front of each hemisphere | Planning, decisions, attention, self-control, personality; movement (motor cortex); speech production (Broca’s area) |
| Parietal lobe | Top and back, behind the central sulcus | Touch, pain and temperature (somatosensory cortex); body position; spatial awareness; numbers |
| Temporal lobe | Sides, below the lateral fissure | Hearing; understanding language (Wernicke’s area); recognising faces and objects; memory |
| Occipital lobe | Back of the brain | Vision: shape, colour, movement |
| Cerebellum | Under the back of the cerebrum | Balance, posture, coordination, timing, learning movements |
| Brainstem | Between the brain and spinal cord | Breathing, heart rate, blood pressure, swallowing, sleep and wakefulness; carries all brain–body signals |
| Corpus callosum | Deep, between the hemispheres | Connects left and right hemispheres |
| Thalamus | Centre of the brain | Relays sensory signals (except smell) to the cortex; alertness |
| Hypothalamus & pituitary | Below the thalamus | Body temperature, hunger, thirst, sleep rhythm; controls hormones |
| Hippocampus | Inside the temporal lobes | Forming new memories; spatial navigation |
| Amygdala | Inside the temporal lobes | Emotions, especially fear; emotional memory |
Some functions are stronger on one side: for most people, language relies mostly on the left hemisphere, while some aspects of attention to space and recognising faces rely more on the right. But the popular idea that people are “left-brained” (logical) or “right-brained” (creative) is not supported by evidence: a study of more than 1,000 brain scans found no sign that individuals use one whole hemisphere more than the other (Nielsen et al., 2013). Creative and logical thinking both use networks in both hemispheres.
A neuron fires an electrical impulse (an action potential) along its axon; at a synapse it releases chemical neurotransmitters that excite or inhibit the next neuron. Fast, insulated (myelinated) axons carry signals at up to about $120\,\mathrm{m/s}$. The white matter you see inside the brain is made mostly of these myelinated axons, while the grey matter of the cortex holds the cell bodies.
The brain has three main parts: the cerebrum (the large folded upper part with two hemispheres and four lobes), the cerebellum (under the back, for balance and coordination) and the brainstem (connecting the brain to the spinal cord and controlling breathing and heart rate). Deep structures such as the thalamus, hypothalamus, hippocampus and amygdala sit inside.
Key takeaway: cerebrum, cerebellum and brainstem, plus deep structures inside.The frontal lobe handles planning, decisions, personality and movement; the parietal lobe processes touch, body position and space; the temporal lobe handles hearing, language understanding and memory; and the occipital lobe processes vision. Each hemisphere has all four lobes.
Key takeaway: frontal = thinking and movement, parietal = touch and space, temporal = hearing and memory, occipital = vision.The cerebellum coordinates movement: it keeps your balance and posture, times and smooths your movements, and helps you learn motor skills such as riding a bicycle. It holds about 80% of the brain’s neurons even though it is only about a tenth of its volume.
Key takeaway: balance, coordination and movement learning.The brainstem (midbrain, pons and medulla) controls automatic life-support functions — breathing, heart rate, blood pressure — plus reflexes such as swallowing, coughing and blinking, and sleep and wakefulness. All signals between the brain and the body pass through it.
Key takeaway: automatic survival functions and the brain–body connection.No. Brain scans show activity across virtually the whole brain over a normal day, and damage to almost any area causes some loss of function. The brain is also too energy-hungry for evolution to keep 90% of it idle. The 10% claim is a popular myth.
Key takeaway: we use virtually all of our brain.No. Some functions, such as language, lean to one hemisphere, but brain imaging of over 1,000 people found no evidence that individuals are “left-brained” or “right-brained” overall. Both hemispheres work together on almost every task.
Key takeaway: hemispheres specialise a little, but people are not left- or right-brained.The hippocampus, inside each temporal lobe, is key for forming new memories of facts and events. Memories are then stored across the cortex, the amygdala adds emotional weight, the frontal lobe helps search for and use memories, and the cerebellum stores movement skills.
Key takeaway: the hippocampus forms new memories; many areas store them.Emotions come from a network often called the limbic system. The amygdala detects threats and drives fear, the hypothalamus triggers the body’s response (such as a faster heartbeat), and the frontal lobe interprets and regulates feelings.
Key takeaway: amygdala + hypothalamus + frontal lobe work together on emotions.