Jun Kim

Electrophysiologist, Director of AF center, Asan Medical Center; University of Ulsan College of Medicine; Husband; Father of two sons;

[Ihtesham Ali @ihtesham2005]

A Norwegian neuroscientist spent 20 years proving that the act of writing by hand changes the human brain in ways typing physically cannot, and almost nobody outside her field has read the paper.

Her name is Audrey van der Meer.

She runs a brain research lab in Trondheim, and the paper that closed the argument was published in 2024 in a journal called Frontiers in Psychology. The finding is brutal enough that it should have changed every classroom on Earth.

The experiment was simple. She recruited 36 university students and put each one in a cap with 256 sensors pressed against their scalp to record brain activity. Words flashed on a screen one at a time.

Sometimes the students wrote the word by hand on a touchscreen using a digital pen, and sometimes they typed the same word on a keyboard. Every neural response was recorded for the full five seconds the word stayed on screen.

Then her team looked at the part of the data most researchers had ignored for years, which is how different parts of the brain were communicating with each other during the task.

When the students wrote by hand, the brain lit up everywhere at once.

The regions responsible for memory, sensory integration, and the encoding of new information were all firing together in a coordinated pattern that spread across the entire cortex. The whole network was awake and connected.

When the same students typed the same word, that pattern collapsed almost completely.

Most of the brain went quiet, and the connections between regions that had been alive seconds earlier were nowhere to be found on the EEG.

Same word, same brain, same person, and two completely different neurological events.

The reason turned out to be something nobody had really paid attention to before her work. Writing by hand is not one motion but a sequence of thousands of tiny micro-movements coordinated with your eyes in real time, where each letter is a different shape that requires the brain to solve a slightly different spatial problem.

Your fingers, wrist, vision, and the parts of your brain that track position in space are all working together to produce one letter, then the next, then the next.

Typing throws all of that away. Every key on a keyboard requires the exact same finger motion regardless of which letter you are pressing, which means the brain has almost nothing to integrate and almost no problem to solve.

Van der Meer said it plainly in her interviews.

Pressing the same key with the same finger over and over does not stimulate the brain in any meaningful way, and she pointed out something that should scare every parent who handed their kid an iPad.

Children who learn to read and write on tablets often cannot tell letters like b and d apart, because they have never physically felt with their bodies what it takes to actually produce those letters on a page.

A decade before her, two researchers at Princeton ran the same fight using a completely different method and ended up at the same answer. Pam Mueller and Daniel Oppenheimer tested 327 students across three experiments, where half took notes on laptops with the internet disabled and half took notes by hand, before testing everyone on what they actually understood from the lectures they had watched.

The handwriting group won by a wide margin on every question that required real understanding rather than surface recall.

The reason was hiding in the transcripts of what the two groups had actually written down.

The laptop students typed almost word for word, capturing more total content but processing almost none of it as they went, while the handwriting students physically could not write fast enough to transcribe a lecture in real time, which forced them to listen carefully, decide what actually mattered, and put it in their own words on the page.

That single act of choosing what to keep was the learning itself, and the keyboard had quietly skipped the choosing and skipped the learning along with it.

Two studies. Two countries. Same answer.

Handwriting makes the brain work. Typing lets it coast.

Every note you have ever typed instead of written went into your brain through a thinner pipe. Every meeting, every book highlight, every idea you captured on your phone instead of on paper was processed at half depth.

You did not forget those things because your memory is bad. You forgot them because typing never woke the part of the brain that would have made them stick.

The fix is the thing your grandmother already knew.

Pick up a pen. Write the thing down. The slower road is the faster one.

[Heart Rhythm Case Reports @HRS_CaseReports]

Contained pulmonary vein injury presenting as a hemorrhagic bulla post–pulsed field ablation: A case report
@Deepti_RG @Dr_JozaEP
https://t.co/ghJmXHpzkt

[Raphael Martins @MartinsRaphae15]

☢️STAR may silence VT, but long-term safety is still being defined. We report the first delayed ventricular septal defect occurring 2 years after STAR for VT, with dosimetric concordance at the VSD site
⚡️Long-term follow-up data are needed
@JACCJournals
https://t.co/yEGr1aNzhy

[ALBERTO ALFIE @ALFIEEP1]

After 20 yrs in EP, I’ve never seen hype like PFA. Point-by-point RF—when done properly—delivers excellent results, with no clear superiority of PFA. Are we driven by better outcomes, or by speed, simplicity, and industry momentum? Time to refocus on science over marketing.

[Daniel Alyesh @DanielAlyeshmer]

An analysis of cognition for post ablation patients stopping anticoagulants from ALONE AF:

[Jun Kim @mdjunkim]

@DrMCardiology @jeffrey_vinocur Absolutely!

[Jun Kim @mdjunkim]

9 yr 9 months old fractured pacer leads implanted outside hospital

[Jun Kim @mdjunkim]

@paulkimbx @jeffrey_vinocur Locking stylet could not be advanced into the inner coils. As Needle’s eye snare is not available, an ablation catheter and gooseneck snare was used as described before(PMID 27014349).

[Jun Kim @mdjunkim]

Rhythm in colors # HRS 2026 in Chicago

[Jun Kim @mdjunkim]

After extraction and implant new pacer

[Jun Kim @mdjunkim]

post RF activation map for LSP AF with 6 yr 2 months duration

[Jun Kim @mdjunkim]

Historical CPVI by RFA

[HeartRhythm @hrs_journal]

Histopathology of the Atrial Tissue After Pulsed-Field Ablation: A Subacute-Phase Lesion in an Autopsy Heart

https://t.co/EFBR1GgpL2

[JK Han MD @netta_doc]

Bringing the 🔥 @drjohnm brings the case AGAINST concomitant #LAAO at the time of #AFib #ablation - highlighting OCEAN, ALONE-AF & lack of evidence!

Ablate, and then stop #DOAC if successful - LAAO should await ablation results.

#WAFib2026

[AATS @AATSHQ]

Researchers in Beijing recently published this #JTCVS article, finding that for patients with isolated MB & systolic coronary compression ≥70%, & refractory to medical therapy, myotomy had better outcomes than medical therapy. Log in to read: https://t.co/GlReiKHlju
#HeartMonth

[HeartRhythm @hrs_journal]

Iatrogenic Aortic Dissection During Catheter Ablation for Ventricular Arrhythmia

https://t.co/V7GCZa5qBV

[Sumit Verma @sumitvermaep]

AnteroLat pap PVC and multi focal PVCs from adjacent scar. ESI and InHeart for the win.
@AbbottCardio @inheartmedical @slate11p

[HeartRhythm @hrs_journal]

Assessment of persistent atrial fibrillation arrhythmogenesis in the right atrium using digital twins

@NTrayanova @trayanovalab @JHU_ADVANCE

https://t.co/g5gX3EC70b

[Jun Kim @mdjunkim]

AT in a patient with MVR and TAP. Mapping still matters.

[HeartRhythm @hrs_journal]

Permanent damage to implantable cardioverter-defibrillators during left-sided septal ventricular tachycardia ablation using a lattice-tip catheter: a case series #OpenAccess

@SCYap77

https://t.co/0dIrTaG1f3