The cortex is divided into four lobes, frontal for planning and movement, parietal for touch and space, temporal for hearing, language, and memory, and occipital for vision. Beneath the cortex sit the limbic structures, notably the amygdala for emotional salience and the hippocampus for memory, while the cerebellum coordinates movement and the brainstem runs the body's automatic functions.
Key terms before the tour
A few words recur throughout, so it helps to fix them first.
- Cortex
- The thin, folded outer sheet of the cerebrum, only a few millimetres thick, where most higher processing happens. Divided into four lobes per hemisphere.
- Lobe
- One of four broad territories of each hemisphere, named after the skull bones above them: frontal, parietal, temporal, occipital.
- Limbic system
- A loose grouping of deep structures involved in emotion, memory, and motivation. The amygdala and hippocampus are its best-known members.
- Subcortical
- Literally below the cortex: the structures buried inside the brain rather than on its folded surface.
The four cortical lobes
Every point on the cortex belongs to one of four lobes, and while the boundaries are partly conventional, they capture real differences in what each stretch of cortex tends to do. Reading them front to back is a natural order.
| Lobe | Rough location | What it leans towards |
|---|---|---|
| Frontal | Front, behind the forehead | Planning, decision-making, self-control, and voluntary movement. Its forward part, the prefrontal cortex, is central to judgement and personality. A strip at its rear edge, the motor cortex, issues movement commands. |
| Parietal | Top and upper-rear | Touch, temperature, and body position, plus spatial awareness: knowing where things are and where your limbs are. A strip along its front edge, the somatosensory cortex, receives touch from across the body. |
| Temporal | Sides, near the ears | Hearing and much of language comprehension, plus a large role in memory through structures buried within it. Also central to recognising faces and objects. |
| Occipital | Back of the head | Vision, almost exclusively. Signals from the eyes arrive here first and are progressively built up into edges, shapes, motion, and, further forward, recognisable scenes. |
A caution worth repeating: these are leanings, not sealed rooms. Language, for instance, is often described as temporal, yet it also draws heavily on frontal regions for production and on connections between them. The lobes are a useful filing system, not a wiring diagram of who does exactly what.
Naming a region for its main job is like naming a city for its biggest industry. It is true and useful, and it hides the fact that the place does a great deal else besides.
The limbic system: emotion and memory
Descend beneath the cortex and you reach a set of older structures, grouped loosely under the name limbic system, that deal with emotion, memory, and motivation. They are ancient in evolutionary terms and sit at the crossroads between raw bodily states and considered thought. Two are famous enough to know by name.
Amygdala
A small almond-shaped cluster, one in each hemisphere, that flags things as emotionally important, especially threats. It gives experiences their emotional charge and helps the rest of the brain react quickly to danger, well before slower, deliberate thought catches up. It is not simply a fear centre, but fear is where its role is clearest.
Hippocampus
A curved, seahorse-shaped structure essential for forming new long-term memories and for spatial navigation. When it is damaged, someone may keep old memories yet be unable to lay down new ones. It works with the surrounding cortex rather than storing everything itself, acting as a hub that helps bind memories together.
The limbic structures are a good illustration of the network idea. The amygdala does not feel fear on its own; it tags salience and then recruits the body, the brainstem, and the cortex to produce the full experience and response. Emotion is a whole-brain event with the amygdala as one important node.
The cerebellum: smoothing the output
At the back of the brain, tucked beneath the cerebrum, sits the cerebellum, the little brain. Though it takes up only around a tenth of the brain's volume, it contains a remarkable share of its neurons, packed into a densely folded sheet. Its classic job is motor: it takes the rough intentions issued by the cortex and refines them into smooth, well-timed, balanced movement. Reach for a cup without spilling it and the cerebellum is quietly doing the fine adjustment.
Its role does not stop at movement. Modern work links the cerebellum to timing and to some forms of learning and cognition, suggesting it applies the same knack for smoothing and coordination to mental processes as well as physical ones. It is a good reminder that the neat labels of older textbooks keep softening as research finds structures doing more than first supposed.
The cerebellum also shows why raw size can mislead. It is far smaller than the cerebrum, yet its tightly packed sheet holds a striking proportion of all the brain's neurons, arranged in an unusually regular, repeating circuit. That orderly wiring is part of why it can process streams of sensory and motor information so quickly and correct movements in real time. Size on its own tells you little; what matters is how many cells there are and how they are connected, a lesson that recurs whenever a small structure turns out to punch above its apparent weight.
The brainstem: the life-support core
Finally, the brainstem: the stalk where the brain meets the spinal cord. It is small, but nothing about it is minor. It regulates breathing, heart rate, blood pressure, swallowing, and the cycle of sleep and waking, the automatic processes that continue whether or not you are paying attention. Every signal travelling between the body and the higher brain passes through it, which is why damage here is so serious. If the cortex is where you decide, the brainstem is what keeps you alive long enough to do the deciding.
The brainstem also houses clusters of cells that broadcast widely to the rest of the brain, helping to set your overall level of alertness and arousal. This is part of why a small, well-placed injury here can have effects out of all proportion to its size: the region is not only a relay but a kind of dimmer switch for the whole system above it. Between them, the three lower structures, brainstem, cerebellum, and the deep limbic clusters, form the quiet infrastructure on which the more celebrated cortex depends. Learn them together and the cortex stops looking like the whole brain and starts looking like the top storey of a much taller building.
A tour, not a taxonomy. Learning the regions is genuinely useful, but resist the urge to file each mental faculty into a single box. The regions here are best read as leading contributors, each the busiest node in a wider network. The next page follows those networks down to the level of individual cells to show how the cooperation actually happens.
Where to go next
Now that you have met the regions, two directions open up. To see how they communicate at the level of neurons and synapses, read how the brain works. To see how these structures relate to mind and behaviour, and what famous cases taught us, visit brain and behaviour. For the bigger picture, the overview ties it together.
Sources
- Kandel ER, Schwartz JH, Jessell TM, et al. Principles of Neural Science. 5th ed. McGraw-Hill; 2013.
- Squire LR. Memory systems of the brain: a brief history and current perspective. Neurobiology of Learning and Memory. 2004;82(3):171-177.
- Herculano-Houzel S. The human brain in numbers: a linearly scaled-up primate brain. Frontiers in Human Neuroscience. 2009;3:31.
This page is educational and describes the general anatomy of the healthy human brain. It is not medical advice and does not diagnose or treat any condition.