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?

[Recusant]

Given the previous item in conjunction with this one, parts of our brains functioning properly will inevitably result in damage to other parts. Seems that a benevolent designer wouldn't have set things up that way, but what do I know.

"We Now Know The Exact Part of The Brain Behind Your Curiosity" | Science Alert

Being curious is a quintessential part of being human, driving us to learn and adapt to new environments. For the first time, scientists have pinpointed the spot in the brain where curiosity emerges.

The discovery was made by researchers from Columbia University in the US, who used functional magnetic resonance imaging (fMRI) scans to measure oxygen levels in different parts of the brain, indicating how busy each region is at any one time.

Knowing where curiosity originates could help us understand more about how human beings tick, and potentially lead to therapies for conditions where curiosity is lacking, such as chronic depression.

[. . .]

Part of what makes the research so fascinating is that curiosity is a fundamental part of being human, key to our survival as a species. Without it, we're not as good at learning and absorbing new information, and there's evidence it drives biodiversity too.

"Curiosity has deep biological origins," says [neuroscientist Jacqueline] Gottlieb.

"What distinguishes human curiosity is that it drives us to explore much more broadly than other animals, and often just because we want to find things out, not because we are seeking a material reward or survival benefit."

[Link to the full article.]

The paper is behind a paywall.

Abstract:

Humans are immensely curious and motivated to reduce uncertainty, but little is known about the neural mechanisms that generate curiosity. Curiosity is inversely associated with confidence, suggesting that it is triggered by states of low confidence (subjective uncertainty). The neural mechanisms of this process, however, have been little investigated. What are the mechanisms through which uncertainty about an event gives rise to curiosity about that event?

Inspired by studies of sensory uncertainty, we hypothesized that visual areas provide multivariate representations of uncertainty, which are then read out by higher-order structures to generate signals of confidence and, ultimately, trigger curiosity. During fMRI, participants (17 female, 15 male) performed a new task in which they rated their confidence in identifying distorted images of animals and objects and their curiosity to see the clear image. To link sensory certainty and curiosity, we measured the activity evoked by each image in occipitotemporal cortex (OTC) and devised a new metric of "OTC Certainty" indicating the strength of evidence this activity conveys about the animal vs. object categories.

We show that, consistent with findings using trivia questions, perceptual curiosity peaked at low confidence. Moreover, OTC Certainty negatively correlated with curiosity, establishing a link between curiosity and a multivariate representation of sensory uncertainty. Finally, univariate (average) activity in two frontal areas – vmPFC [ventromedial prefrontal cortex--manages perceptions of value and confidence] and ACC [anterior cingulate cortex--used for information gathering]– correlated positively with confidence and negatively with curiosity, and the vmPFC mediated the relationship between OTC Certainty and curiosity. The results suggest that multiple mechanisms link curiosity with representations of confidence and uncertainty.

Press release from Columbia University on this paper.

[zorkan]

Why is it called the hippocampus when it looks nothing like a seahorse or a camp hippopotamus?

People in the past had real brains.
Newton, Galileo and Einstein lived in an age when people had to think for themselves.
Today, people have their thinking done for them.

[Recusant]

Well done.

[Recusant]

Still on the hippocampus trail. One recalls a neuroscientist in who's work the hippocampus features.   

"How the human hippocampus contributes to value-based decision-making under uncertainty" | Medical Express

Value-based decision-making is the process through which humans choose between options associated with different costs or efforts, as well as rewards. These choices include, for instance, selecting different products at the grocery stores or making substantial lifestyle changes to accomplish a specific goal.

Past studies on animals have found that the hippocampus, a key brain region associated with learning and memory, could play a role in the processing and evaluation of rewards, which is thought to also occur during value-based decision-making. In addition, research on humans has linked the hippocampus to memory, associative learning and imagination, which could also be connected to value-based decision-making.

Researchers at University of Oxford have recently been investigating the role of this brain region in the valuation and selection of different options. In one study involving individuals with cognitive impairments, they found that the hippocampus could support the active gathering of information that precedes value-based decisions in situations where outcomes are uncertain.

Their latest paper, published in Nature Human Behaviour, built on these findings to further explore how the hippocampus contributes to human decision-making under uncertainty. In this new work, they specifically examined how individuals with a neurological condition affecting the hippocampus decided between different options associated with varying rewards.

"The role of the hippocampus in decision-making is beginning to be more understood," Bahaaeddin Attaallah, Pierre Petitet and their colleagues wrote in their paper.

"Because of its prospective and inferential functions, we hypothesized that it might be required specifically when decisions involve the evaluation of uncertain values. A group of individuals with autoimmune limbic encephalitis (ALE)—a condition known to focally affect the hippocampus—were tested on how they evaluate reward against uncertainty compared to reward against another key attribute: physical effort."

[. . .]

Attaallah, Petitet and their colleagues found that patients diagnosed with ALE were sensitive to uncertainty, yet they were less sensitive to information related to changes in reward values and effort. Their study gathered evidence suggesting that the hippocampus has a context-sensitive role in value-based decision-making, which is specifically relevant under conditions of uncertainty and influences how they evaluate the rewards and efforts linked with different options.

[Continues . . .]

The paper is open access:

"The role of the human hippocampus in decision-making under uncertainty" | Nature Human Behavior

Abstract:

The role of the hippocampus in decision-making is beginning to be more understood. Because of its prospective and inferential functions, we hypothesized that it might be required specifically when decisions involve the evaluation of uncertain values.

A group of individuals with autoimmune limbic encephalitis—a condition known to focally affect the hippocampus—were tested on how they evaluate reward against uncertainty compared to reward against another key attribute: physical effort.

Across four experiments requiring participants to make trade-offs between reward, uncertainty and effort, patients with acute limbic encephalitis demonstrated blunted sensitivity to reward and effort whenever uncertainty was considered, despite demonstrating intact uncertainty sensitivity. By contrast, the valuation of these two attributes (reward and effort) was intact on uncertainty-free tasks. Reduced sensitivity to changes in reward under uncertainty correlated with the severity of hippocampal damage. Together, these findings provide evidence for a context-sensitive role of the hippocampus in value-based decision-making, apparent specifically under conditions of uncertainty.

[Recusant]

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?

These Green dialogs age well.