All things brain...

[No one]

What a fowl thing to say.

You might want to duck and cover, otherwise, I'd say your goose is cooked.

[Tank]

Oh dear. One for the "near-death" folks.

"Scientists Detect Brain Activity in Dying People Linked to Dreams, Hallucinations" | Vice

We've all heard eerie stories about people who almost perished, but survived to tell the tale of the strange visions and emotions they experienced when they were close to death. Now, scientists have observed a surge of energetic activity in the brains of dying patients, a discovery that reveals that our brains can be active even as our hearts stop beating, reports a new study.

The results challenge a longstanding assumption that brains become nonfunctional as they lose oxygen during cardiac arrest, and could eventually open a new window into the weird phenomena associated with near-death experiences (NDE). 


Jimo Borjigin, an associate professor of neurology at the University of Michigan, has been interested in these questions since she first observed surges of activity in the brains of dying rats a decade ago. The surges consisted of gamma waves, the fastest oscillations in the brain, which are associated with conscious perceptions, lucid dreams, and hallucinations.

Now, Borjigin and her colleagues have discovered similar gamma activity in the brains of patients who died in the hospital while they were monitored by electroencephalogram (EEG) sensors, which record neural activity. The researchers examined EEG readings from a small sample size of four unresponsive patients who were removed from life support with the permission of their families. During cardiac arrest, two of the people experienced complex gamma activity in a "hot zone" of the brain that is critical for conscious processing.

[. . .]

"The dying brain was thought to be inactive; our study showed otherwise," said Borjigin, the senior author of the study, in an email to Motherboard. "The discovery of the marked and organized gamma activities in the dying brain suggests that NDE is the product of the dying brain, which is activated at death."

[Continues . . .]

The paper is open access:

"Surge of neurophysiological coupling and connectivity of gamma oscillations in the dying human brain" | PNAS

Abstract:

The brain is assumed to be hypoactive during cardiac arrest. However, animal models of cardiac and respiratory arrest demonstrate a surge of gamma oscillations and functional connectivity.

To investigate whether these preclinical findings translate to humans, we analyzed electroencephalogram and electrocardiogram signals in four comatose dying patients before and after the withdrawal of ventilatory support. Two of the four patients exhibited a rapid and marked surge of gamma power, surge of cross-frequency coupling of gamma waves with slower oscillations, and increased interhemispheric functional and directed connectivity in gamma bands. High-frequency oscillations paralleled the activation of beta/gamma cross-frequency coupling within the somatosensory cortices.

Importantly, both patients displayed surges of functional and directed connectivity at multiple frequency bands within the posterior cortical "hot zone," a region postulated to be critical for conscious processing. This gamma activity was stimulated by global hypoxia and surged further as cardiac conditions deteriorated in the dying patients. These data demonstrate that the surge of gamma power and connectivity observed in animal models of cardiac arrest can be observed in select patients during the process of dying.

Interesting findings.

[MarcusA]

My brain is always giving me trouble.

[Recusant]

Oh dear. One for the "near-death" folks.

"Scientists Detect Brain Activity in Dying People Linked to Dreams, Hallucinations" | Vice

[. . .]

Interesting findings.

Yes, something to point out the next time one of the JAQ "but what about near death experiences??" types wanders in. 

[MarcusA]

The art of war is attrition and sleath.

[Recusant]

Onward . . .

"Mysterious Spiral-Shaped Signals Detected in The Human Brain" | Science Alert

There are many layers to the human brain. From its wrinkled exterior to its darkest depths, scientists are trying to understand them all. But in honing in on the brain's intricate neural circuitry, they appear to have overlooked patterns of activity swirling on the surface.

A team of fluid physicists from the Universty of Sydney in Australia and Fudan University in China discovered brain signals rippling across the brain's outermost layer of neural tissue, the cerebral cortex, on scans of 100 young adults' brains. Signals naturally arranged as spirals, like vortices in a draining bathtub or whirlwinds of turbulent air.

"Gaining insights into how the spirals are related to cognitive processing could significantly enhance our understanding of the dynamics and functions of the brain," says senior author Pulin Gong, a physicist at the University of Sydney.

The cortex is the wrinkled outer layer of neuron-dense tissue that folds into the two hemispheres of our brain, responsible for computing complex cognitive functions such as language and storing memories.

Neuroscientists have mostly focused on mapping brain activity from the bottom up to understand the inner workings of regions like the cortex: imaging cells to determine how they communicate as networks that give rise to their function.

In an exciting twist, the team analyzed brain imaging data collected as part of the Human Connectome Project using methods most familiar to fluid physicists studying complex wave patterns in turbulent flows.

. . .

[Continues . . .]

The paper is behind a paywall.

Abstract:

The large-scale activity of the human brain exhibits rich and complex patterns, but the spatiotemporal dynamics of these patterns and their functional roles in cognition remain unclear. Here by characterizing moment-by-moment fluctuations of human cortical functional magnetic resonance imaging signals, we show that spiral-like, rotational wave patterns (brain spirals) are widespread during both resting and cognitive task states.

These brain spirals propagate across the cortex while rotating around their phase singularity centres, giving rise to spatiotemporal activity dynamics with non-stationary features. The properties of these brain spirals, such as their rotational directions and locations, are task relevant and can be used to classify different cognitive tasks.

We also demonstrate that multiple, interacting brain spirals are involved in coordinating the correlated activations and de-activations of distributed functional regions; this mechanism enables flexible reconfiguration of task-driven activity flow between bottom-up and top-down directions during cognitive processing. Our findings suggest that brain spirals organize complex spatiotemporal dynamics of the human brain and have functional correlates to cognitive processing.

[Tank]

Well I'll be darned!

[Icarus]

I'll put this here for want of a better place.  I have long subscribed to the notion that different people have different periods of efficiency, serious cogitation or willing physical activity.  Circadian clock ?


https://www.quantamagazine.org/in-our-cellular-clocks-shes-found-a-lifetime-of-discoveries-20231010/?utm_source=pocket-newtab-en-us

[Recusant]

I'll probably remember this item, damage be damned. Featuring the hippocampus again. 

"Every New Memory You Make Causes Damage to Your Brain Cells" | Science Alert

New research reveals that the process of remembering something long-term comes at a cost – specifically, inflammation in the brain and DNA damage in nerve cells, as the memories get 'fused' into neurons and stored.

The international team of researchers suggests that memory formation is not unlike making an omelet by breaking a few eggs: some careful destruction is required before a new memory pattern can form.

Based on tests on mice carried out for the study, this happens inside the hippocampus, a part of the brain already known to be the primary storage locker for our memories and crucial to the process of remembering.

"Inflammation of brain neurons is usually considered to be a bad thing, since it can lead to neurological problems such as Alzheimer's and Parkinson's disease," says neuroscientist Jelena Radulovic from the Albert Einstein College of Medicine in New York.

"But our findings suggest that inflammation in certain neurons in the brain's hippocampal region is essential for making long-lasting memories."

The team triggered episodic memory in mice with brief, mild electric shocks. Close analysis of hippocampal neurons revealed the activation of genes in the Toll-Like Receptor 9 (TLR9) pathway, important for inflammatory signaling. What's more, this pathway was only activated in clusters of neurons, which also showed DNA damage.

While breaks in DNA in the brain happen often, they're usually repaired very quickly. Here, the changes seemed more significant, with biological processes usually linked to cell division apparently being used to organize neurons into memory-forming clusters without dividing the cells.

The inflammatory editing mechanisms in the mice lasted a week, after which the memory-storing neurons were found to be more resistant to outside forces. This suggests that memories are then locked in for good and protected from external interference. Something similar likely happens in the human brain, too.

"This is noteworthy because we're constantly flooded by information, and the neurons that encode memories need to preserve the information they've already acquired and not be distracted by new inputs," says Radulovic.

When the same TLR9 inflammatory pathway was blocked in the mice, they could no longer be trained to remember the electric shocks. The absence of TLR9 also led to more severe DNA damage, not unlike that seen in neurodegenerative disorders.

Blocking the TLR9 pathway has been proposed to treat or prevent long-term COVID-19, but this study suggests that the idea may need rethinking. Most of all, though, it's an intriguing new insight into how memories are stored in the brain.

[Continues . . .]

The paper is open access:

"Formation of memory assemblies through the DNA-sensing TLR9 pathway" | Nature

Abstract:

As hippocampal neurons respond to diverse types of information, a subset assembles into microcircuits representing a memory. Those neurons typically undergo energy-intensive molecular adaptations, occasionally resulting in transient DNA damage.

Here we found discrete clusters of excitatory hippocampal CA1 neurons with persistent double-stranded DNA (dsDNA) breaks, nuclear envelope ruptures and perinuclear release of histone and dsDNA fragments hours after learning. Following these early events, some neurons acquired an inflammatory phenotype involving activation of TLR9 signalling and accumulation of centrosomal DNA damage repair complexes. Neuron-specific knockdown of Tlr9 impaired memory while blunting contextual fear conditioning-induced changes of gene expression in specific clusters of excitatory CA1 neurons. Notably, TLR9 had an essential role in centrosome function, including DNA damage repair, ciliogenesis and build-up of perineuronal nets.

We demonstrate a novel cascade of learning-induced molecular events in discrete neuronal clusters undergoing dsDNA damage and TLR9-mediated repair, resulting in their recruitment to memory circuits. With compromised TLR9 function, this fundamental memory mechanism becomes a gateway to genomic instability and cognitive impairments implicated in accelerated senescence, psychiatric disorders and neurodegenerative disorders. Maintaining the integrity of TLR9 inflammatory signalling thus emerges as a promising preventive strategy for neurocognitive deficits.

[The Magic Pudding..]

I'll probably remember this item, damage be damned. Featuring the hippocampus again. 

I'll try not to, or no more than the gist of the gist.
I think I can use it to advantage.
You said we'd travel when we had more time, how about Europe in May?
Do you realise the damage a trip like that would do to our hippocampuses?
Oh well, there's a new TV series that sounds good.
Hippocampuses.
Detectorists again?