The Brodmann map divides the human cerebral cortex into distinct numbered regions based on their microscopic cell structure, and more than a century after its creation, it remains the most widely used system for talking about where things happen in the brain. Korbinian Brodmann, a German neurologist, first presented his classification in 1903, identifying areas that differ in how their neurons are organized into layers. What makes the map enduring is that many of these structurally distinct zones turned out to correspond remarkably well to distinct functions, from processing what you see and hear to planning movements, understanding speech, and regulating emotions. The full picture, though, is richer and messier than a neat numbered list might suggest.
How Brodmann Built the Map
Brodmann worked by slicing brain tissue into extremely thin sections, staining them with chemicals that highlighted cell bodies, and examining the results under a microscope. What he noticed was that the cortex is not uniform. Different patches have different arrangements of cells across their six main layers: some layers are thicker or thinner, some contain distinctive large cells, and the density of neurons varies from region to region. By painstakingly cataloguing these differences across the entire cortical surface, he arrived at 52 areas, each assigned a number in roughly the order he studied them. The numbers themselves carry no functional meaning; area 17 is not “higher” than area 4. They are labels of convenience that stuck.
Brodmann was influenced by leading neuroanatomists of his era, and his mapping became what researchers still call the lingua franca of cortical localization.1PubMed Central. Korbinian Brodmann (1868-1918) and his contributions to mapping the cerebral cortex Modern imaging at very high resolution can resolve the same layered patterns Brodmann identified, confirming that the laminar structure of the cortex really does vary in ways that track his original boundaries.2Europe PMC. Cytoarchitecture of the human cerebral cortex: MR microscopy of excised specimens at 9.4 Tesla That structural foundation is what gives the map its staying power: Brodmann areas are not arbitrary slices of brain. They reflect genuine differences in the hardware.
Vision and the Occipital Cortex
The back of the brain is where visual information first arrives, and two Brodmann areas dominate early visual processing. Area 17, also called the primary visual cortex or V1, is the brain’s first stop for signals relayed from the eyes through the thalamus. It sits along a deep fold called the calcarine sulcus and contains a detailed spatial map of the visual field: neighboring points in what you see activate neighboring neurons in area 17. Area 18, immediately surrounding it, corresponds to V2 and begins to process more complex features like edges and contours.
Functional brain imaging has confirmed that these structurally defined areas align well with functionally defined visual regions. When researchers compared probability maps drawn from cell-structure analysis with maps drawn from brain-scan activations, the agreement between area 17 and the functionally mapped V1, and between area 18 and V2, was strong.3PubMed. Linking retinotopic fMRI mapping and anatomical probability maps of human occipital areas V1 and V2 Studies using functional MRI to map the visual field onto V1 have confirmed that the area preserves a point-by-point representation of what the eyes take in, organized by polar coordinates across the flattened cortical surface.4PubMed. Functional analysis of primary visual cortex (V1) in humans Beyond areas 17 and 18, the occipital lobe houses additional visual regions (V3, V4, V5, and more) that handle color, motion, and depth. But the tight correspondence between Brodmann’s structural areas and modern functional maps is strongest for these earliest stages.
Touch, Hearing, and the Primary Sensory Strips
Running along the postcentral gyrus, just behind the brain’s central sulcus, you find areas 3a, 3b, 1, and 2. Together they form the primary somatosensory cortex, where touch, pressure, temperature, and body-position signals are processed. These areas are organized somatotopically, meaning there is a rough body map laid out across the cortical surface: neurons handling your hands sit next to those handling your face, and so on. Within areas 3b and 1, researchers have found additional borders that likely correspond to representations of different types of sensory receptors or different body regions.5PubMed. Areas 3a, 3b, and 1 of human primary somatosensory cortex The amount of cortex devoted to a body part does not match the part’s physical size; your fingertips and lips get a disproportionately large share because of their dense receptor populations.
For hearing, the key areas are 41 and 42, tucked into the superior temporal gyrus on each side of the brain. Area 41 is the primary auditory cortex, where sound first registers as a cortical signal. Its fundamental job is frequency analysis: different positions along the cortex respond best to different pitches, creating what is called a tonotopic map. Area 42 sits adjacent and handles more complex auditory processing. Mapping tonotopy precisely in humans proved difficult for years, partly because the auditory cortex is physically small and folded into a deep fissure, but recent high-resolution imaging has brought human findings more in line with what was already understood from primate studies.6PubMed. The Map of Auditory Function
Movement and the Motor Cortex
Directly in front of the central sulcus lies area 4, the primary motor cortex. This is the brain’s main output region for voluntary movement, sending signals down through the spinal cord to activate muscles. Area 4 contains exceptionally large neurons called Betz cells, and like the somatosensory cortex behind it, it is organized as a body map: stimulating different zones triggers movement in different body parts.7PubMed. Functional neuroanatomy of the primate isocortical motor system Again, the hands and face claim outsized territory, reflecting the fine control required for gripping objects and producing speech.
Area 6, just anterior to the primary motor cortex, contains the premotor cortex and the supplementary motor area. These regions are involved in planning and sequencing movements before they are executed. If area 4 is the player pressing the keys on a piano, area 6 is the part of the brain reading ahead in the sheet music. Still further forward, areas 8 and parts of area 9 participate in directing eye movements and coordinating attention toward targets you intend to look at or reach for. The frontal eye fields in area 8 are particularly important for voluntary gaze shifts.
Language Areas and Their Surprising Complexity
Two of the most famous Brodmann areas are 44 and 45, which together make up Broca’s area in the left frontal lobe. Damage here has long been associated with difficulty producing speech. But imaging studies have revealed that these two neighboring areas actually do different things during language tasks. Area 44 is more involved in the structural side of language: assembling words into grammatically correct sequences and building syntactic hierarchies.8Cerebral Cortex. Building by Syntax: The Neural Basis of Minimal Linguistic Structures Area 45, meanwhile, leans more toward semantic processing, helping to retrieve word meanings and handle the conceptual content of what you are saying.9PubMed. Analysis of neural mechanisms underlying verbal fluency in cytoarchitectonically defined stereotaxic space–the roles of Brodmann areas 44 and 45 When researchers stripped away all semantic cues from a language task, leaving only bare syntactic structure, only area 44 activated, confirming its role as a core region for processing pure grammar.10PubMed. The language skeleton after dissecting meaning: A functional segregation within Broca’s Area
On the other end of the language circuit sits area 22 in the left temporal lobe, traditionally called Wernicke’s area and long thought to be the seat of language comprehension. The real picture is more complicated. Reduced blood flow to area 22 during a stroke does predict how severe a person’s difficulty understanding words will be.11PubMed. Hypoperfusion of Wernicke’s area predicts severity of semantic deficit in acute stroke But modern imaging and neuropsychological evidence suggest that this region actually plays a larger role in speech production than was traditionally believed, blurring the classic textbook division between a “production area” in the front and a “comprehension area” in the back.12PubMed Central. The Wernicke area: Modern evidence and a reinterpretation Language, it turns out, relies on a widely distributed network rather than two discrete boxes.
Brain tumor surgery has given clinicians a direct window into this network. During operations near language-critical regions, surgeons track connectivity between areas 44 and 45 and the rest of the language network. Follow-up imaging after such procedures has shown that the brain can functionally reorganize connections among these Brodmann areas, redistributing language processing to preserve speech ability even after tissue is removed.13PubMed. Enhancing brain tumor surgery precision with multimodal connectome imaging: Structural and functional connectivity in language-dominant areas
The Prefrontal Cortex and Higher-Order Thinking
The prefrontal cortex, spanning roughly the front third of each hemisphere, is where the Brodmann map gets especially crowded with numbered areas, and where some of the brain’s most distinctly human capacities reside. Areas 9 and 46, located on the outer (dorsolateral) surface of the frontal lobe, are central to working memory, the ability to hold information in mind and manipulate it in real time. Damage to the left dorsolateral prefrontal cortex impairs the manipulation of verbal information, while damage to the right side disrupts a broader range of reasoning tasks involving spatial or abstract material.14PubMed Central. Dorsolateral prefrontal contributions to human working memory
Further down on the underside of the frontal lobe lies the orbitofrontal cortex, which encompasses areas 11, 13, 14, and 47. This region is central to decision-making, reward valuation, and emotional regulation. Area 11 is more involved in weighing the value of choices, area 13 contributes to emotion regulation, and the orbital-polar region handles reward processing and self-referential thought, the kind of thinking involved when you consider how an outcome matters to you personally.15PubMed. The Structural and Functional Connectivity of the Orbitofrontal Cortex: Deconvoluting Brodmann Areas 11, 13, 14, and 47 Damage to this region often produces striking personality changes: patients may become impulsive, socially inappropriate, or unable to learn from negative consequences, even though their memory and intelligence test scores remain normal.
Error Detection, Emotion, and Internal Awareness
On the brain’s medial wall, area 24 and adjacent areas form the anterior cingulate cortex. This region sits at a crossroads between emotion and cognition. One of its core functions is detecting when something has gone wrong or is likely to go wrong. Research using combined computational modeling and brain imaging has shown that the anterior cingulate learns to predict the probability of making an error in a given situation, not just flagging mistakes after they happen but anticipating them before they occur.16PubMed. Learned predictions of error likelihood in the anterior cingulate cortex This makes it central to the kind of mental recalibration you experience when a task gets harder or your strategy stops working.
Deeper in the brain’s folds, the insular cortex (which Brodmann mapped but which does not have a single clean number in his system) plays a role that has received increasing attention in recent years. The insula contains topographic maps of visceral and bodily sensations: pain, temperature, hunger, thirst, heartbeat awareness, and even taste. These maps are organized from back to front, with raw sensory representations in the posterior insula gradually being integrated into emotional feelings and conscious awareness toward the front.17PubMed Central. An insula hierarchical network architecture for active interoceptive inference When people talk about “gut feelings,” the insula is a big part of the neural machinery behind that experience.
Association Areas and Multimodal Integration
Many Brodmann areas do not fall neatly into a single-function category. Area 37, in the temporal-occipital junction, is a good example. The right fusiform gyrus in this area is selectively important for recognizing and remembering faces. Stimulating it electrically or boosting its activity with noninvasive brain stimulation selectively improves working memory for faces but not for other objects.18PubMed. Non-invasive brain stimulation targeting the right fusiform gyrus selectively increases working memory for faces But on the left side, part of area 37 functions as the visual word form area, a region that becomes specialized for recognizing written words as a person learns to read. Damage to this left-hemisphere region causes pure alexia, an inability to recognize written words despite otherwise intact vision and language. A meta-analysis of brain activation studies confirmed that area 37 participates in both language and visual perception tasks, serving as a genuine multimodal hub.19PubMed Central. Language and Visual Perception Associations: Meta-Analytic Connectivity Modeling of Brodmann Area 37
The posterior parietal cortex, encompassing areas 5, 7, 39, and 40, is another major integration zone. These areas build spatial maps of your surroundings and your body’s position within them. They are critical for reaching and grasping, for knowing where objects are relative to you, and for shifting attention from one location to another. Damage to the posterior parietal cortex on both sides produces Bálint’s syndrome, a devastating condition in which a person can see individual objects but cannot perceive the spatial layout of a scene, cannot accurately reach for things, and cannot voluntarily direct their gaze.20Current Biology. The posterior parietal cortex Area 39 (the angular gyrus) and area 40 (the supramarginal gyrus) also contribute to reading, arithmetic, and semantic understanding, which is why strokes in this region often cause a bewildering combination of spatial and cognitive deficits.
Why the Map Does Not Perfectly Fit Every Brain
For all its usefulness, the Brodmann map has real limitations. The biggest is individual variability. When researchers brought areas 17 and 18 into standardized brain coordinates and compared them across individuals, they found high variability in the size, shape, and exact location of each area relative to visible landmarks like folds and grooves on the brain surface.21PubMed. Brodmann’s areas 17 and 18 brought into stereotaxic space-where and how variable? What this means in practice is that saying “area 17 is in the calcarine sulcus” is a useful generalization, but the exact boundaries shift from person to person. Two people’s area 17 can differ in total surface area by a factor of two or more.
Brodmann also worked from a handful of brains, drawing borders by eye. Modern efforts have tackled both problems. The Human Connectome Project used multiple types of brain imaging simultaneously, including structural scans, functional activation, connectivity patterns, and cortical thickness measurements, to create a new parcellation of 180 areas per hemisphere. This updated map represents a major advance over relying on Brodmann’s hand-drawn parcellation from 1909 and can be automatically generated for individual people from their own brain scans.22PubMed Central. A multi-modal parcellation of human cerebral cortex The new map does not replace Brodmann numbers in everyday scientific communication, partly because the numbering system is so deeply embedded in the literature, but it highlights how much finer-grained the real architecture is than 52 areas can capture.
Brodmann Areas in Evolutionary Perspective
Comparing Brodmann-style maps across species has revealed which parts of the cortex expanded most dramatically in human evolution. The prefrontal cortex underwent a major expansion in the human lineage, though the growth occurred in concert with other association areas rather than in isolation. Interestingly, current evidence does not support the idea that humans gained a large number of entirely new prefrontal areas; instead, existing areas became larger and their connections became more elaborate.23PubMed Central. Evolution of prefrontal cortex
Zooming out further, a multilevel atlas comparison across primate species found that Old World monkeys, apes, and humans share a distinctive evolutionary trend: their frontal and parietal lobes expanded disproportionately compared to other mammals, which tend to show the strongest expansion in the occipital lobe. Within this group, the prefrontal cortex was the principal driver of frontal growth. Humans carry the most enlarged frontal and parietal lobes among primates, but the pattern is an acceleration of a trend shared across the entire Old World primate lineage rather than a uniquely human leap.24PubMed Central. Multilevel atlas comparisons reveal divergent evolution of the primate brain The areas that expanded most, including the dorsolateral prefrontal cortex and the posterior parietal cortex, are the same ones associated with working memory, planning, spatial reasoning, and language, suggesting that the cognitive abilities most often cited as distinctly human are rooted in expansions of areas already present in our primate relatives.
When Brodmann Areas Rewire Themselves
One of the more striking findings in modern neuroscience is that Brodmann areas retain their structural organization even when they never receive the sensory input they were “designed” for. In people born completely blind, the visual cortex (areas 17, 18, and beyond) does not go silent. Instead, these regions get repurposed for other tasks, including language, auditory processing, and spatial reasoning using touch. Yet even in congenitally blind individuals, functional connectivity within the visual cortex still follows retinotopic organizational principles, maintaining the same spatial divisions of labor seen in sighted people: eccentricity, laterality, and elevation distinctions all remain intact.25Brain. Functional connectivity of visual cortex in the blind follows retinotopic organization principles The connectivity-based organization extended from the primary visual cortex through higher-order visual areas and into the parietal and ventral temporal regions.
This finding says something profound about the nature of Brodmann areas. Their internal wiring scheme is not simply a product of the sensory experience that flows through them during development. It is laid down by genetic and developmental programs that operate independently of experience, creating a structural scaffold that the brain can then repurpose for whatever input is available. It also means that a blind person’s area 17 is not the same functionally as a sighted person’s area 17, even though their cell architecture and connectivity blueprints look remarkably similar. The Brodmann number tells you about the hardware; the function that hardware serves depends on the brain’s lifelong history of use.
Areas That Are Rarely Discussed
Popular accounts of the Brodmann map tend to focus on the greatest hits: areas 4, 17, 22, 44, and 45. But many numbered areas get far less attention, partly because their functions are harder to pin down and partly because they overlap heavily with neighboring regions in what they do. Areas 25 and 32, in the subgenual and pregenual portions of the cingulate cortex, have become important targets for depression research. Deep brain stimulation aimed at area 25 has been explored as a treatment for severe, treatment-resistant depression, based on the finding that this region is hyperactive in some patients with persistent depressive states.
Areas 35 and 36, forming the perirhinal cortex in the medial temporal lobe, are important for recognizing whether something is familiar. They work alongside the hippocampus (which is not part of the Brodmann map, being an allocortical structure with a different layering scheme) to support memory formation. Areas 28 and 34, the entorhinal cortex, serve as the main gateway between the hippocampus and the rest of the cortex and are among the first regions to show damage in Alzheimer’s disease, which is why difficulty forming new memories is often the earliest symptom.
Area 10, the frontopolar cortex occupying the very tip of the frontal lobe, is proportionally larger in humans than in any other primate. It has been linked to multitasking, prospective memory (remembering to do something in the future), and the ability to hold one goal in mind while pursuing another. These are the kinds of abstract, future-oriented cognitive operations that are difficult to study in animal models, which is one reason this region remains less well understood than sensory or motor areas despite its likely importance to everyday human cognition.