Left versus right brain strokes vary significantly in long-term effects

Due to the high complexity of the brain, the aftereffects of a stroke can have widely different manifestations, ranging from minor temporary impairments to rapid death. Whether a stroke results in paralysis, speech impairments, loss of bodily function, or death will depend on whether it occurs in the left or right hemispheres or the brain stem.

Someone suffers from a stroke every 40 seconds

Every 40 seconds, someone in the US experiences a stroke—and every minute without treatment destroys millions of brain cells. This explainer breaks down the two main types of strokes, their risk factors, and how early detection could change outcomes in the future.

Medical recognition of strokes stretches back to ancient Greece

Every minute, 750 milliliters of blood flows to the brain, supplying 20% of the body’s oxygen. A sudden disruption—whether from a clot (ischemic stroke) or a bleed (hemorrhagic stroke)—can be life-threatening. From ancient Greek theories to modern CT and MRI scans, here’s how stroke science has evolved over time.

An estimated 2 million brain cells die each minute a stroke goes untreated

Modern stroke treatment is a delicate balance between obtaining an accurate diagnosis and delivering treatment quickly. Each stroke has its own cause, and the appropriate treatment must be paired with the correct diagnosis to prevent further harm. Typical treatments pair emergency surgery to relieve the affected area and long-term regimens to avoid recurrence.

Using AI to restore speech 30 years after a stroke

Through a novel surgical procedure involving electrodes implanted in the brain, along with the help of artificial intelligence, a stroke patient is regaining her ability to speak. This technology converts her thoughts into speech through a digital avatar, allowing her to verbally express herself for the first time in decades.

Visualize a stroke at the microscopic level.

Take a quiz to discover your brain care score

Each year, nearly 800,000 Americans have a stroke. With such a high occurrence rate, you may be asking yourself what you could do now to prevent a future stroke. Researchers at Harvard collaborated to answer this question by coming up with a "Brain Care" scoring system. Take the quiz to learn the quality of your brain health today and pick up helpful insights to lower your risk of stroke and dementia well into the future.

Scientists are studying dying patients' brain activity in the final moments of life

In the final moments of life there are distinctive bursts of coordinated neural activity. Researchers are interested in parsing that data to better understand the dying process and also exploring how this data relates to our understanding of consciousness.

How a brain injury created a mathematical mind

In 2002, two men savagely attacked Jason Padgett outside a karaoke bar, leaving him with a severe concussion--and turning Padgett into a mathematical genius.

Brain activity sometimes goes into overdrive around the point of death according to researchers' recent analysis of patients' brains before and after they were taken off their ventilators.

'Susan's Brain': what happens to the brain during addiction

This engaging animation from Harvard Online breaks down the neuroscience of addiction through the story of “Susan’s brain,” demonstrating how addictive substances hijack normal reward pathways. Through clear visual metaphors and approachable narration, it explains complex brain chemistry in understandable terms.

A stroke occurs when blood flow to part of the brain is suddenly interrupted, either by a blockage (ischemic stroke) or bleeding when a blood vessel in the brain breaks and bleeds (hemorrhagic stroke).

What happens in a dying brain?

Near-death experiences usually happen during death or on the border of life and death when a person isn't understood to be conscious. This article details the science of what's going on with the brain during NDEs.

Losing a brain-computer interface can trigger lasting psychological distress

A clinical trial participant with severe epilepsy described becoming “one” with her implant after it gave her unprecedented control over her seizures. When the device was removed due to the company shutting down, she experienced deep emotional trauma and a sense of personal loss.

Visualize the difference between a healthy brain and one with Alzheimer's.

The brain has three main parts—the cerebrum, brain stem, and cerebellum—each combining to control the entirety of the body's operations. Alzheimer's progressively deteriorates the circuitry in these structures, resulting in what we see as the symptoms of the disease.

An essay exploring how living day-to-day with a brain implant helps restore a sense of identity

Companies like Neuralink are experimenting with volunteers who have lost control over their bodies. Many of the program's participants claim the most significant benefit from the tool is the ability to perform simple, mundane tasks, such as playing video games or shaking hands, rather than more obvious milestones like walking or eating. This essay explores what it's like, day to day, to use a brain implant.

What a railroad spike through the head taught science about the brain

In 1848, a railroad worker survived an accident that drove a 13-pound iron bar through his head. The injury changed his personality, and our understanding of the brain.

Pig brain cellular activity was restarted hours after death in study published in 2019

Yale University scientists restored basic cellular activity and circulatory function in pig brains about four hours after death with a synthetic cocktail of preservatives and nutrients. This work— which didn't restart electricity activity in the brain or consciousness—could help advance future human stroke and brain injury treatments.

'FAST': An acronym to remember stroke symptoms to look for

The primary factor in surviving a stroke is how quickly one gets the appropriate medical treatment. “FAST” refers to the four most noticeable symptoms of a stroke: face-dropping ("F"), arm weakness ("A"), speech difficulty ("S"), and "time to call 911" ("T").

How burnout alters your brain

Stress is a normal part of everyday life, and it’s not necessarily all bad. But chronic stress—the kind that leads to burnout—can change the size and functioning of parts of your brain. It can alter the ability to make new brain cells and memories and even potentially modify your DNA.

How science explains déjà vu

Take a fun look at the science explaining the odd experience of déjà vu, which some theories suggest is actually a sign of a healthy brain.

Depression changes the brain, causing distinct structural alterations visible on brain scans, but effective treatment can eventually make a depressed brain resemble a healthy one.

Stress and the brain

While an acute stress response is a normal bodily function, the effects of chronic stress can be extremely damaging to the human body. This is particularly true with regard to the brain. This article explores the effects of stress on the human brain, including how chronic stress may lead to psychological conditions such as depression and memory loss.

What happens to your brain when you burn out?

You've probably heard of burnout, also known as the feeling of exhaustion that happens after a long period of being overwhelmed or stressed. It's often associated with work and careers, but other parts of life, like parenting, can cause burnout, too. Scientists are figuring out what happens, biochemically speaking, in the brain when burnout hits—and spoiler alert, it includes a neurotransmitter called glutamate. Watch this video to learn more.

Physiological changes to the brain on LSD can be captured via MRI

Psychedelics like LSD often take users on novel experiences that can result in lasting shifts in perspective and behavior. See how LSD affects brain activity in this video that details how scientists visually captured the psychedelic's effect for the first time.

Grief rewires the human brain

The human brain handles stress and emotional traumas similarly. In response to the emotional stress of a situation like the death of a loved one, divorce, or abuse, the brain may strengthen or weaken connections between nerves to form new neural connections. Over time, chronic stress can diminish brainpower, reducing overall nerve growth and memory to shift resources to enable elevated fear responses and enable humans to survive.

How do brain scans work?

There's only one thing in our solar system sophisticated enough to study itself: the human brain. But this self-investigation is challenging because a living brain is shielded by skull, swaddled in tissue, and made up of billions of tiny cells. How do we study living brains without harming their owners? Two experts explain how the various techniques like EEGs, fMRIs, and PETs work in this TedEd talk.

Watch this 2021 video demonstrating a full brain death examination

This video and accompanying article in the peer-reviewed New England Journal of Medicine show the then-standard steps of a full brain death examination—demonstrating the process on a medical dummy to search for pain, blinking, eye movement, cough, gagging, or other forms of responsiveness. (May need to sign up for a free account to view.)

The neuroscience of heartbreak

An analysis of functional MRIs revealed a difficult fact: the active brain areas of people experiencing heartbreak were very similar to those actively in love. This is a major reason why people in the middle of rejection can't accept the reality of their loss. This article breaks down the various changes in neurotransmitters and neural pathways for those enduring that universal experience, heartbreak.

How tPA, which helps dissolve blood clots, can lessen the severity of a stroke

One of the most exciting recent advances in treating stroke is a medication known as tissue plasminogen activator, or tPA. It is only effective for use in some ischemic strokes, and it must be delivered within 4.5 hours of symptom onset to have a chance at working.

Sharp wave ripples in the brain tag experiences for long-term memory storage

These ripples were known to quickly replay neuronal sequences during sleep for consolidation. While awake, they help the brain prioritize memories to remember, and their disruption can impair memory formation.

The body's response to cardiac arrest has been linked to near-death experiences.

How family members disappeared into dementia

This narrative feature describes one family's troubling experience with frontotemporal dementia, or FTD, which emerges in the prime of adult life — as young as 40, in some cases — and degrades the brain's ability to plan, organize, express language, understand social cues, and exercise judgment.

Brain training game creates long-lasting changes in the brain that may help protect against dementia.

Searching for Albert Einstein's stolen brain

Within moments of Einstein's 1955 death, someone reportedly ferreted away the 76-year-old genius's brain. Decades later, a reporter's editor told them to solve the case. This 64-minute podcast episode follows the work of Steven Levy, the reporter who ultimately tracked down Einstein's brain, which had been sliced and stored in slides, goo, and a cardboard box in a scientist's office.

A first-person account of receiving an Alzheimer's diagnosis

Having Alzheimer's is a bit like having a part of your brain sliced away each day, according to author Greg O'Brien. This 34-minute podcast episode introduces O'Brien and his co-host, author David Shenk, as the two embark on a multi-season conversation on Alzheimer's disease and O'Brien's diagnosis.

Four in 10 CPR patients report consciousness not captured by standard measures.

Medical advances that manage to resuscitate people from comas and cardiac arrests have enabled new research into the brain activity of people experiencing near-death experiences and a new (contested) explanation about why they occur.

Open brain surgery is not required for BCIs inserted via blood vessel injection

Synchron's brain-computer interface, the Synchron Switch, takes advantage of preexisting medical devices, such as stents and catheters. Cells grow over the device over a 90-day period, incorporating it into the vessel wall and minimizing clots.