The Map of the Brain — Neighborhoods with Their Own Jobs, a City Joined by Roads

Why Paralyzed on the Right Means the Left Brain

A seventy-two-year-old father was hospitalized because a cerebral blood vessel was blocked. His right arm and right leg lost strength, and the words he wanted to say did not come to mind and he could not form them well. The doctor points to a photograph taken of his head and explains that the left brain was injured. The family tilts their heads in confusion. The side that lost strength is the right body, but why is the injured part the left brain?

There is a long-standing answer to this question. The brain has a map. Because it is quite consistent which things collapse when a certain spot is injured, doctors look at symptoms to guess the injured spot and confirm it with a photograph. That map was first drawn by observing people with brain injuries for a long time.

The map also has limits. Even when the same spot is injured, people's symptoms differ slightly, and events in distant, uninjured spots are shaken together. This article divides the brain into large chunks, looks at why the left body is handled by the right brain and why speech is mostly concentrated in the left brain, and follows how far that map is correct.

Breaking the Brain Down Into Large Masses

When you look inside the skull, the first thing you see is a large, wrinkled mass. The cerebrum is the largest part of the brain, filling most of the inside of the skull, and is divided into two halves, left and right, by a deep groove down the middle. A cerebral hemisphere is the name for either the left or the right half of the cerebrum.

The cerebral cortex is the thin layer covering the outside of the brain, a place where regions that take charge of movement, speech, and sensation are spread out.

The outside of the cerebrum is broadly divided into four regions from the forehead side to the back of the head, and each such region is called a lobe. The frontal lobe is the front part of the brain situated behind the forehead. High-level work such as setting goals and regulating thoughts and actions accordingly is commonly discussed in connection with the frontal lobe (PMID 27251123).

The parietal lobe is the upper part of the brain situated beneath the crown of the head, and is involved in receiving sensations coming up from the body to gauge where my body and the outside world are located within space. The temporal lobe is the side part of the brain situated inside the temple above the ear, and is involved in hearing sounds and understanding speech.

The occipital lobe is the back part of the brain situated inside the back of the head, and is mainly in charge of seeing things that enter through the eyes. The names of all four lobes come from the places on the head where those lobes are placed.

At the rearmost edge of the frontal lobe lies a band from which instructions to move the body go out. The motor cortex is the cerebral cortex that passes like a band from the top of the head across both sides along the rearmost edge of the frontal lobe, sending out instructions to move the body. It has been explained that this band contains a small map where body parts are laid out in order. In reality, the regions for each body part overlap each other considerably and change in various situations (PMID 11562847). Even the most famous map inside the brain is not a picture with neatly separated boxes.

If you compare the brain to a city, the lobes are the large neighborhoods of the city. Much like a neighborhood with a city hall or a neighborhood with a port, the neighborhoods of the brain have their primary responsibilities posted like nameplates.

The Small Brain Below the Cerebrum, the Stem, and the Deep Places

Just below the back of the cerebrum, beneath the back of the head, sits another small mass. The cerebellum is a small brain located below the rear of the cerebrum, beneath the back of the head, responsible for smoothing out movements and keeping the body's balance. A neuron is the basic cell of the brain and nerves that receives an electrical signal and passes it to the next cell. Despite its small size, the cerebellum holds most of the brain's neurons (PMID 40074407).

The cerebellum governs the initiation and continuation of movement, its speed, balance, and muscle tension. When the cerebellum is injured, movements usually become uncoordinated, eye movements get disrupted, and severe dizziness can occur (PMID 40973045). The authors of a review explain that the cerebellum calculates in advance what state the body is about to be in, and when this calculation goes wrong, the hand overshoots or falls short of the target (PMID 32962256). A hand trying to pick up a cup stopping short of it or knocking it away is an example.

The work of the cerebellum may not end with movement. The cerebellum was long considered to be solely responsible for movement, but as problems with thought and emotion were confirmed in patients with cerebellar injury, its role has expanded toward thought and emotion (PMID 18602745). A consensus statement gathered from multiple researchers agrees that the cerebellum plays a part in thinking, while noting that this conclusion still relies heavily on inference (PMID 23996631). Exactly what the cerebellum adds to thought and emotion is not yet clear (PMID 18602745).

The brainstem is the stem-like part extending from the very bottom of the brain toward the neck. The brainstem connects upward to the cerebrum side, downward to the spinal cord, and backward to the cerebellum (PMID 41896011). The spinal cord is a central nervous system extending from the brain down along the inside of the backbones, serving as a pathway holding neurons where commands and sensations travel back and forth between the brain and the body.

The brainstem governs basic life functions such as breathing, heartbeat, and blood pressure, as well as consciousness and sleep (PMID 20483389). The motor instructions descending from the cerebral cortex and the sensory pathways ascending from the spinal cord also pass through this stem (PMID 20483389). There is an arousal system that starts in the brainstem, passes through the thalamus, and spreads broadly to the cerebral cortex, and when this system breaks down, coma and similar states occur (PMID 19573504). Studies that gathered the injury sites of brain-injured people and mapped them onto the brain's network accurately delineated the brainstem sites that consistently cause coma when injured (PMID 36242637). Breathing and wakefulness both hang on a single short stem above the neck.

Deep in the middle of the cerebrum, there are also famous places. The thalamus is a pair of masses placed left and right deep in the middle of the cerebrum, serving as a relay station connecting signals rising from the body and brainstem to the cerebral cortex. A group of cells inside the thalamus stands at the crossroads connecting information rising from the spinal cord and brainstem with the cerebral cortex, and is involved in processing thought, wakefulness, consciousness, and pain signals (PMID 37292456).

The hippocampus is a small region deep inside the temporal lobe, essential for turning newly experienced events into long-lasting memories. How memories are put in and kept is covered in "The Three Steps of Memory — Putting It In, Keeping It, Taking It Out".

The Right Brain Controls the Left Body

The command to move starts in the motor cortex and travels down to the spinal cord. The corticospinal tract is a bundle of nerves running straight from the motor cortex to the spinal cord. Most of the nerve fibers in this bundle control the movement of the opposite side of the body, and only a few fibers run down the same side to play a part in the movement of the same-side body (PMID 11562847). The fine movements of the ends of the limbs, like fingers, are mainly handled by the corticospinal tract descending from the opposite cerebrum, while the movements and posture of the trunk and the bases of the limbs are controlled on both sides by other pathways descending from the brainstem (PMID 42039090). The pathways carrying bodily sensations upward also mostly reach the opposite cerebrum.

This crossing determines the side of the brain that is injured and the side where symptoms appear. A stroke is a disease where blood to the brain is suddenly blocked or bursts, damaging the brain tissue that received that blood. In records collected by a stroke center over 20 years, among 2,433 patients confirmed by MRI to have a stroke caused by a blocked blood vessel in one side of the cerebrum and weakness on one side of the body, 4 people (0.16%) had weakness on the same side of the body as the injured brain (PMID 42406906). An MRI is an examination that uses magnets and radio waves to take pictures inside the body, showing not only bones but also soft tissues like discs and nerves.

The authors concluded that same-side paralysis is rare and appears to be reported more often in younger patients and those who have suffered a stroke before, while noting that because the data gathers literature cases and records from a single center, it should be interpreted with caution (PMID 42406906). In these rare exceptions, the rewiring of motor pathways, the dual management of movement by both cerebral hemispheres, and unusual anatomical pathway structures are discussed together (PMID 42406906).

Therefore, weakness from a stroke in the cerebrum usually occurs on the side of the body opposite the injured cerebrum. Sudden weakness in the face, arm, or leg on one side, or slurred speech, are symptoms covered as emergency signs in "What a Stroke Actually Is — Blocked, Burst, and the Clock", and that piece explains what those signs mean and why time changes the outcome. The location guessed from symptoms is confirmed through physical examination and imaging. Even in densely packed areas like the brainstem, MRI makes it possible to find and point to the structures explaining the patient's symptoms (PMID 20483389).

The right cerebrum mainly controls the left body, and the left cerebrum mainly controls the right body.

Maps Drawn by Those Who Were Injured

The idea that different parts of the brain have different jobs first became famous in an unlikely place. The physician Franz Joseph Gall (1758–1828) and Johann Gaspar Spurzheim (1776–1832), who first advanced this theory alongside him, built a theory connecting the outer shape of the head to a person's character. This theory was heavily criticized because it lacked repeatedly verifiable evidence, and it was also used to prop up ideas that degraded race and women. Still, the central idea—that different parts of the brain are responsible for different tasks—stimulated later research (PMID 42676358).

The early squares of the map came not from head shapes, but from injured brains. The French physician Marc Dax and the surgeon and anatomist Paul Broca left pioneering work revealing the connection where speech disorders appeared in people with injuries to the left cerebrum (PMID 32433927). Aphasia is a condition where the ability to make or understand speech collapses due to brain injury. This observation exposed the property that the left and right sides of the brain are different from each other (PMID 32433927).

The method of matching the injured site and the collapsed work lent weight for a long time to the side that one region governs one task (PMID 34881727). The same method also grew the opposing idea. The idea that the brain works through widely spread connections is also over a hundred years old, and although it initially relied on studies of injured people and nerve bundles inside the brain, it was largely ignored until recently (PMID 33101120).

With the advent of brain imaging, it became possible to watch the brain of a living person while they are working. As a result, it was revealed that left-right biases are widespread even in memory, decision-making, and emotion beyond speech, and that they are not fixed but can change (PMID 32433927). Functional MRI is a test that tracks MRI signals showing changes in the amount of oxygen carried by blood in each part of the brain, indirectly showing which part is working harder.

There is something to be careful about when reading these pictures. In functional MRI studies that gathered the parts that light up while reading emotions from other people's faces, the results for individual spots did not reproduce well between studies, and when grouped into networks connected by those spots, the reproducibility was higher (PMID 35654963). The spot that lights up in the picture is a spot that got busy together while doing that job. A single picture does not tell us that that spot takes charge of that job alone, or even that it is the cause of that job.

When removing brain tumors that develop close to areas responsible for movement or speech, stimulating the brain directly during surgery to find the area responsible for that function has become the standard method (PMID 32388682). This means that textbook maps alone make it difficult to pinpoint that area precisely in any one person's brain.

Brain maps were first drawn from people with brain injuries, and brain imaging expanded those maps to the living brain.

Speech Usually on the Left — One-Sided Bias

Lateralization is the property where the left and right cerebral hemispheres take on different shares of certain tasks. The fact that the left hemisphere primarily handles much of speaking and understanding speech is one of the best-known examples of lateralization in the human brain (PMID 24769292). Whether someone is right-handed or left-handed is also linked to this bias to some extent, but the strength of that link varies depending on how it is measured, and the underlying basis in the brain for language bias and hand bias is different (PMID 24769292).

Even a single piece of language is split between the two hemispheres. The networks that process sentence structure are clearly biased toward the left, the networks that process word meanings are less biased, and the intonation and melody of speech are primarily handled by networks in the right hemisphere (PMID 22013214).

There are also left-right differences in the body's physical structure. In an analysis pooling MRIs of 17,141 healthy individuals from 99 datasets worldwide, the left cerebral cortex was generally thicker and smaller in surface area than the right, and left-right differences were seen in regions involved in lateralized tasks like language and spatial processing. In this analysis, no clear link was found between left-right differences and handedness (PMID 29764998).

This bias varies from person to person. Unlike the arrangement of internal organs like the heart, left-right differences in the brain vary among individuals, and a significant minority have a reversed bias or no bias at all (PMID 29198268). "Speech is on the left" is a map that fits most people.

Extending this bias to human personality gives us terms like "left-brained" and "right-brained." One study surveying 2,193 active-duty teachers in Ecuador classified "left-brain/right-brain dominance" as a neuromyth and cited it as one of the things teachers believe in most (PMID 41274777). Because this is the result of surveying teachers in one country, it cannot be directly applied to other countries. It has also been pointed out that viewing the left and right brains as two paired systems is itself an oversimplification. The brain contains many networks that perform different tasks, and the direction and degree of bias differ for each network (PMID 29198268).

The two hemispheres do not work separately; they are connected by a bridge. The corpus callosum is the largest nerve bundle connecting the left and right cerebral hemispheres, serving as the main communication highway between the two halves. Classic observations emerged from people who underwent surgery to cut the corpus callosum to relieve severe epilepsy that could not be controlled with medication. An object seen in the right visual field could be named aloud and selected with the right hand, whereas an object seen in the left visual field would prompt the statement "I saw nothing" while the left hand still selected it accurately (PMID 31923846).

These observations have been interpreted to mean that the separated two hemispheres see separately and react separately. Since then, evidence has accumulated that this separation is not absolute (PMID 31923846), and the current consensus is that there is insufficient evidence to answer whether the consciousness of someone with a severed corpus callosum is also split into two (PMID 32399946).

Because lateralization is a property that varies by task and by person, it does not mean that a person's entire brain leans toward one side.

Work Travels on Roads

Let us imagine walking through a grocery store with a shopping list in our heads, realizing an item we wanted is out of stock, and pivoting to buy something else. Executive function is a high-level mental faculty that regulates thoughts and actions toward a goal, encompassing abilities such as suppressing impulsive reactions, holding and revising information in mind, and shifting from one task to another. These abilities are intertwined yet can be measured separately, and they are not identical to general intelligence (PMID 27251123).

Executive function is most frequently discussed in connection with the frontal lobes. Impairments in executive function were initially described in patients with frontal lobe injuries. Today, it is understood that executive function relies on a widespread network spanning not only the prefrontal cortex, but also the parietal cortex, subcortical nuclear groups deep within the cerebrum, the thalamus, and the cerebellum. Consequently, a deficit can arise from an injury to any of those sites, or to the neural fiber bundles connecting them (PMID 26039846).

A brain network is an interconnected system where disparate regions are linked by neural fiber bundles to accomplish a task together. As it became established that the prefrontal cortex participates in large-scale networks, it came to be accepted that cognitive impairments arise not only from damage to a single site within a network, but also from degenerative diseases targeting that network (PMID 34881727). One review proposes that complex thoughts and behaviors emerge from the binding of multiple networks, each specialized to some degree. The authors explain that this architecture accounts for why human behavior varies considerably, and why certain functions can be partially recovered after a brain injury (PMID 32078778).

To use a city analogy, work does not finish within a single neighborhood; it happens by riding the roads that connect neighborhoods. If a single bridge is blocked, businesses in distant neighborhoods that relied on that bridge for traffic also become quiet. A similar phenomenon is captured on imaging in the brain. Following a stroke caused by a blocked blood vessel, there are instances where the structure itself remains intact, yet activity, blood flow, and metabolism decrease in distant regions that were connected to the injured site. In an analysis pooling 3,021 participants across 66 studies, the rate at which this change was captured on imaging was 53% overall, ranging from 28% to 67% depending on the imaging method (PMID 41594771).

The authors concluded that this phenomenon depends primarily on the location of the injured site and its remote connectivity, rather than the patient's age or stroke severity. They also noted that how this change shifts over time and its exact clinical significance remain to be further elucidated (PMID 41594771).

Networks also stand upon physical locations. In the human brain, various regions with designated roles are linked to form large networks, and during various tasks, the activity of each region can be predicted quite accurately by how that region is connected (PMID 36250457). The authors concluded that connectivity may serve as the infrastructure that dictates brain activity (PMID 36250457). City roads do not erase neighborhoods; they connect them. Just as with the brainstem locations that cause coma or the contralateral muscle weakness seen earlier, the grid squares of the map still pinpoint many things accurately.

The analogy holds true only up to this point. City neighborhoods have boundaries fixed on a map, whereas brain regions have overlapping boundaries and vary slightly from person to person (PMID 11562847, PMID 32078778). The redrawing of the map after an injury is covered in "Neuroplasticity — A Brain That Builds New Roads Beside the Broken Ones".

Although each region of the brain has a primary role, most tasks are performed collaboratively by a network connecting multiple regions, making the idea of "one region = one function" merely an approximation.

Reading Your Father’s Brain Again Through the Map

Let’s go back to our first father. The loss of strength in his right arm and right leg aligns with the fact that motor commands mostly govern the opposite side of the body, pointing to the left cerebral hemisphere (PMID 11562847). The difficulty in forming words also points to the left hemisphere, which primarily handles speech in most people (PMID 24769292). Both symptoms point to the same side, and the scan also shows the left. For this person, the map and the scan match.

The map does not always match like this. There are rare cases where strength is lost on the same side of the body as the injured brain (PMID 42406906), and the left-right bias of the brain varies from person to person, so a notable minority has a reversed bias or none at all (PMID 29198268). This is why we confirm the location guessed by symptoms through physical examination and imaging.

If, after being discharged from the hospital, the father struggles to make plans and carry out tasks in order, looking at just one square of the map cannot fully explain why. Executive function relies on a network spread across multiple locations (PMID 26039846), and after a stroke, reduced activity in distant, uninjured areas is frequently caught on imaging (PMID 41594771). However, just how much this change means for the symptoms is still being figured out. Sorting out where each of this person's symptoms came from is the job of clinical examination and tests.

Where to Look Further

Some squares on the map are still empty. It is not clear precisely what the cerebellum adds to thought and emotion (PMID 18602745), and whether the consciousness of someone whose corpus callosum has been severed is one or two has not been answered either (PMID 32399946).

How a stroke happens and why time matters continues in "What a Stroke Actually Is — Blocked, Burst, and the Clock". How the shape of paralysis varies depending on where the movement's instruction is cut off is covered by "Paralysis and Spasticity — Where the Command Breaks Shapes What Follows", and how the map is redrawn after an injury is covered by "Neuroplasticity — A Brain That Builds New Roads Beside the Broken Ones". The stages of memory handled by the hippocampus begin in "The Three Steps of Memory — Putting It In, Keeping It, Taking It Out".

How nerve cells send and receive signals is covered by "How Do Nerve Cells Send Signals? — A Burning Fuse, a Gap Crossed by Ferry", the paths connecting the brain and body by "The Spinal Cord and Peripheral Nerves — A Trunk Line, and a Loop That Turns Back Halfway", and dementia by "What Is Dementia? — Snow That Settles Without a Sound, a Branch Beginning to Bend". Parkinson's disease, headaches, and epilepsy are topics this series will cover in the future.

Source Papers

• "Revisiting the Functional Anatomy of the Human Brain: Toward a Meta-Networking Theory of Cerebral Functions." (2020) — PMID 32078778 — Criticizes localizationism (one function = one region) as an outdated view and proposes a meta-networking theory that complex cognition arises from the integration of distributed yet relatively specialized networks, explaining individual differences and functional recovery after injury.
• "Anatomy of the brainstem: a gaze into the stem of life." (2010) — PMID 20483389 — The brainstem connects the cerebrum with the medulla and cerebellum, manages breathing, heart rate, blood pressure, consciousness, and sleep, carries motor and sensory fiber bundles, and provides structures where symptoms can be explained via MRI.
• "Stroke-related ipsilateral haemiparesis: a single-centre case series and literature review." (2026) — PMID 42406906 — Among 2,433 patients with single-center 2003–2023 MRI-confirmed unilateral supratentorial acute ischemic stroke and hemiparesis, ipsilateral hemiparesis occurred in 4 patients (0.16%), with candidate mechanisms being corticospinal tract reorganization, bilateral motor representations, and anatomical variation, requiring cautious interpretation due to data heterogeneity.
• "Split-Brain: What We Know Now and Why This is Important for Understanding Consciousness." (2020) — PMID 32399946 — Corpus callosum division broadly disrupts the integration of perception and attention but not absolutely, and current consensus holds that evidence is insufficient to determine whether consciousness splits.
• "Unity and diversity of executive functions: Individual differences as a window on cognitive structure." (2017) — PMID 27251123 — Executive functions are higher-level cognitive processes commonly associated with the frontal lobe (response inhibition, interference control, working memory updating, and shifting), which are correlated yet separable, and distinct from general intelligence.
• "The Many Sides of Hemispheric Asymmetry: A Selective Review and Outlook." (2017) — PMID 29198268 — The notion of a left-right dual system is an oversimplification, as lateralization varies across networks, and a substantial minority are reversed or non-asymmetric.
• "Consensus paper: the cerebellum's role in movement and cognition." (2014) — PMID 23996631 — All authors agree on the cerebellum's cognitive role, but this conclusion remains largely speculative, grounded in observations of patients with cerebellar lesions.
• "Computed tomography and magnetic resonance imaging of the brainstem." (2026) — PMID 41896011 — The brainstem consists of the midbrain, pons, and medulla, connecting upward to the diencephalon, downward to the spinal cord, and backward to the cerebellum, integrating consciousness and breathing cycles, with MRI being the preferred modality.
• "A narrative review of motor control dual pathways: the corticospinal and reticulospinal tracts in synergy and differentiation." (2026) — PMID 42039090 — The corticospinal tract primarily handles contralateral distal fine movements, while the reticulospinal tract bilaterally controls the trunk, proximal muscles, and posture.
• "Prevalence of educational myths among Ecuadorian teachers." (2025) — PMID 41274777 — In a survey of 2,193 in-service Ecuadorian teachers, left-brain/right-brain dominance emerged as one of the most common neurological neuromyths.
• "Understanding, detecting, and stimulating consciousness recovery in the ICU." (2023) — PMID 36242637 — Lesion-network mapping studies map out the brainstem regions that consistently cause coma when damaged.
• "Executive Dysfunction and the Prefrontal Cortex." (2021) — PMID 34881727 — Traditional lesion studies emphasized the functional control of a single region, but as the large-scale network participation of the prefrontal cortex has become established, it is recognized that cognitive impairments arise from both intra-network lesions and degenerative diseases targeting the network.
• "Network Neuroscience and the Adapted Mind: Rethinking the Role of Network Theories in Evolutionary Psychology." (2020) — PMID 33101120 — The distributed network perspective has existed for over a century but was ignored until recently, early network theories relied on lesion and white matter studies, and localizationism is gradually being abandoned.
• "Executive dysfunction." (2015) — PMID 26039846 — Executive dysfunction was first described in frontal lobe lesions but relies on a distributed network involving the prefrontal and parietal cortices, basal ganglia, thalamus, and cerebellum, and can arise from damage to any site or white matter connection.
• "[Functional pathophysiology of consciousness]." (2009) — PMID 19573504 — The ascending reticular activating system (ARAS) projects from the midbrain reticular formation through the thalamus to the cortex, and its destruction causes coma and related states.
• "The Prediction of Brain Activity from Connectivity: Advances and Applications." (2024) — PMID 36250457 — The brain is a large-scale network connecting multiple functionally specialized regions, task-evoked local activity can be accurately predicted from connectivity patterns, and connectivity may serve as the basis determining brain activity.
• "Unmasking the relevance of hemispheric asymmetries-Break on through (to the other side)." (2020) — PMID 32433927 — Marc Dax's and Paul Broca's observations linking left hemisphere damage to speech disorders revealed asymmetry, and the advent of neuroimaging showed that lateralization spans widely to memory, decision-making, and emotion, remaining plastic.
• "The ontogenesis of language lateralization and its relation to handedness." (2014) — PMID 24769292 — Left-hemisphere dominance for speech production and perception is the best-known lateralization, and its correlation with handedness varies depending on measurement methods and neurophysiological underpinnings.
• "Cerebellar neurocognition: insights into the bottom of the brain." (2008) — PMID 18602745 — The cerebellar role has expanded from motor coordination to cognitive and affective regulation, confirming cognitive and emotional impairments in patients with cerebellar damage, though their exact nature remains unclear.
• "Prevalence and Imaging Correlates of Cerebral Diaschisis After Ischemic Stroke: A Systematic Review and Meta-Analysis." (2025) — PMID 41594771 — Across 66 studies and 3,021 individuals, the pooled prevalence of remote functional depression (diaschisis) is 53%, ranging from 28% to 67% depending on imaging modality, with lesion location and long-range connectivity being more decisive than age or severity, while the time course and clinical significance require further research.
• "Neurophysiology of the cerebellum and clinical correlations: a review." (2025) — PMID 40973045 — The cerebellum regulates the initiation, execution, speed, balance, coordination, and muscle tone of movement, lesions generally cause ataxia, abnormal eye movements, and severe dizziness, and it is also recognized as a core component of cognitive circuitry.
• "Dysmetria and Errors in Predictions: The Role of Internal Forward Model." (2020) — PMID 32962256 — Author hypothesis: impaired predictive computation in the internal forward model of the cerebellum causes past-pointing or undershooting, known as dysmetria.
• "Unified tactile detection and localisation in split-brain patients." (2020) — PMID 31923846 — Classical observations of patients who underwent corpus callosum division to treat refractory epilepsy (unable to name objects in the left visual field yet choosing them with the left hand) are supported by accumulating evidence that this separation is not absolute.
• "Mapping cortical brain asymmetry in 17,141 healthy individuals worldwide via the ENIGMA Consortium." (2018) — PMID 29764998 — MRI scans of 17,141 individuals across 99 datasets show that the left cortex is generally thicker and smaller in surface area, with asymmetry in language- and visuospatial-related regions, showing no significant correlation with handedness.
• "The brain basis of language processing: from structure to function." (2011) — PMID 22013214 — The syntactic processing network is distinctly left-lateralized, semantics are less lateralized, and prosody primarily involves right-hemisphere networks.
• "Awake vs. asleep motor mapping for glioma resection: a systematic review and meta-analysis." (2020) — PMID 32388682 — Intraoperative stimulation mapping has become standard in tumor resection near functional areas because it more accurately locates functional regions.
• "[The pyramidal tract: new pathways]." (2001) — PMID 11562847 — Most pyramidal fibers control the contralateral body, with a small minority of uncrossed fibers involved in same-side movement, and the motor cortex's body map overlaps considerably and remains modifiable.
• "The Pseudoscience of Phrenology: A Historical Examination." (2026) — PMID 42676358 — Gall (1758–1828) and Spurzheim's (1776–1832) phrenology was criticized for lacking reproducible evidence and used to promote racist and sexist ideologies, but its central theory of cerebral localization stimulated subsequent research.
• "Cerebellar asymmetries." (2025) — PMID 40074407 — The cerebellum is small yet contains the vast majority of the brain's neurons.
• "The intralaminar thalamus: a review of its role as a target in functional neurosurgery." (2023) — PMID 37292456 — The intralaminar nuclei of the thalamus serve as a nodal point between ascending information from the spinal cord and brainstem and cortical-basal ganglia circuits, participating in cognition, arousal, consciousness, and pain processing.
• "Activation network mapping for integration of heterogeneous fMRI findings." (2022) — PMID 35654963 — Individual brain region-level reproducibility across facial emotion processing fMRI studies is low, whereas network-level reproducibility is higher.