Meta & Fysikken: Afsnit 79: Hjernen
I dette afsnit går vi lidt i dybden omkring den menneskelige hjerne. Hvad er det egentlig for et organ? Hvor meget, eller lidt, ved vi faktisk om vores egen krops kommandocentral?
Her kommer Karina’s noter til dagens afsnit:
Der har været en del nyheder som handler om hjernen
1: Tracking the evolution of the brain
Mammalian brains have four distinct regions or lobes, each with particular functions. The frontal lobe is associated with reasoning and abstract thought, the temporal lobe with preserving memory, the occipital lobe with vision, and the parietal lobe helps to integrate sensory inputs.
The results of our analyses surprised us. Tracking change over deep time across dozens of primate species, we found humans had particularly high levels of brain integration, especially between the parietal and frontal lobes.
Looking at changes in shape through growth revealed that in apes, such as the chimpanzee, integration between the brain's lobes is comparable to that of humans until they reach adolescence.
Vi er mere ens med Neanderthaler end vi troede.
En højere integration imellem hjerne-delene skulle give bedre lære-evner. Hvilket vi mennekser beholder også når vi er voksne.
Metode:
Our first analysis included 3D brain models of hundreds of living and fossil primates (monkeys and apes, as well as humans and our close fossil relatives). This allowed us to map brain evolution over time.
Our other digital brain data set consisted of living ape species and humans at different growth stages, allowing us to chart integration of the brain's parts in different species as they mature.
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2: Scientists Just Uncovered A Whole New Layer of Brain Anatomy
https://www.sciencealert.com/scientists-just-uncovered-a-whole-new-layer-of-brain-anatomy
Forskere fra bla KBH har opdaget et lag i hjernen de kalder SLYM. Subarachnoid LYmphatic-like Membrane
Dette lag af celler er kun et par celler tykt.
This membrane seems to play a role in mediating the exchange of small, dissolved substances between compartments in the brain. It also appears to be the home base of brain-specific immune cells, not to mention assisting in the brain's waste-removal (glymphatic) system.
While much of their research on this structure is so far from mice, using two-photon microscopy and dissections, they have confirmed the SLYM's presence in an adult human brain too.
The SLYM lies between two other membranes protecting the brain. It divides our brain fluid space in two, bringing the total number of known membranes encasing our brain up to four. It appears to act as a barrier for molecules in our brain fluid that are larger than around 3 kilodaltons; comparable to an extremely small protein.
"The discovery of a new anatomic structure that segregates and helps control the flow of cerebrospinal fluid (CSF) in and around the brain now provides us much greater appreciation of the sophisticated role that CSF plays not only in transporting and removing waste from the brain, but also in supporting its immune defenses," says University of Rochester neuroscientist Maiken Nedergaard.
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3:
https://www.sciencealert.com/scientists-show-2-distinct-brain-networks-are-activated-while-reading
https://www.sciencealert.com/a-chance-event-1-million-years-ago-changed-human-brains-forever
https://www.sciencealert.com/a-first-of-its-kind-signal-has-been-detected-in-the-human-brain
https://www.sciencealert.com/paranormal-activity-is-all-in-your-head-and-this-could-explain-why
https://www.sciencealert.com/mysterious-surge-of-activity-detected-in-the-brains-of-dying-people
https://www.sciencealert.com/the-first-ever-complete-map-of-an-insect-brain-is-truly-mesmerizing
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Model af Hjernen:
Kan du huske at vi ville bygge en model af hjernen?
Implicit within this effort is the typical, reductionistic hubris of the physicist: that all of biology and chemistry may be reduced to fundamental physics. But Nature has infinite resolution and patience; we humans don’t in our computer simulations.
Brain Activity Map Project,
In September 2011, a group of neuroscientists and nanoscientists made a not-so-modest proposal: to map the activity of the entire human brain at the level of individual neurons and detail how those cells form circuits.
That knowledge could be harnessed to treat brain disorders like Alzheimer’s, autism, schizophrenia, depression, and traumatic brain injury. And it would help answer one of the great questions of science: How does the brain bring about consciousness?
The Ambition: “a large-scale, international public effort, the Brain Activity Map Project, aimed at reconstructing the full record of neural activity across complete neural circuits.” Like the Human Genome Project a decade earlier, they wrote, the brain project would lead to “entirely new industries and commercial ventures.”
Human Brain Project
Henry Markram is director of Blue Brain, a supercomputing project that can model components of the mammalian brain to precise cellular detail -- and simulate their activity in 3D. Soon he'll simulate a whole rat brain in real time.
https://www.ted.com/talks/henry_markram_a_brain_in_a_supercomputer?language=en
Ten years ago, a neuroscientist said that within a decade he could simulate a human brain. Spoiler: It didn’t happen.
Pro:
In a recent paper titled “The Scientific Case for Brain Simulations,” several Human Brain Project (HBP) scientists argued that big simulations “will likely be indispensable for bridging the scales between the neuron and system levels in the brain.” In other words: Scientists can look at the nuts and bolts of how neurons work, and they can study the behavior of entire organisms, but they need simulations to show how the former create the latter. The paper’s authors drew a comparison to weather forecasts, in which an understanding of physics and chemistry at the scale of neighborhoods allows us to accurately predict temperature, rainfall, and wind across the whole globe.
Con:
Even if it were possible to record all spikes from all neurons at once, a brain doesn’t exist in isolation: in order to properly connect the dots, you’d need to simultaneously record external stimuli that the brain is exposed to, as well as the behavior of the organism. We need to understand the brain at a macroscopic level before trying to decode what the firings of individual neurons mean.
Furthermore: There isn’t a single, agreed-upon theory of how the brain works, and not everyone in the field agreed that building a simulated brain was the best way to study it.
The project is now focused on providing a new computational research infrastructure to help neuroscientists store, process, and analyze large amounts of data—unsystematic data collection has been an issue for the field—and develop 3D brain atlases and software for creating simulations.
https://www.humanbrainproject.eu/en/explore-the-brain/
The US BRAIN Initiative, meanwhile, underwent its own changes. Early on, in 2014, responding to the concerns of scientists and acknowledging the limits of what was possible, it evolved into something more pragmatic, focusing on developing technologies to probe the brain.
In September, researchers using these advances will publish a detailed classification of cell types in the mouse and human motor cortexes—the biggest single output from the BRAIN Initiative to date.
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AI afkoder hjernen:
https://www.sciencealert.com/ai-experiment-decodes-brain-scans-to-reveal-things-people-are-thinking