i-was-today-years-old-when
i learned that if you could accelerate continually at just 1g you could travel to the other side of the known universe within your lifetime (x)
neurosciencestuff
In a uniquely deep and detailed look at how the commonly used anesthetic propofol causes unconsciousness, a collaboration of labs at The Picower Institute for Learning and Memory at MIT shows that as the drug takes hold in the brain, a wide swath of regions become coordinated by very slow rhythms that maintain a commensurately languid pace of neural activity. Electrically stimulating a deeper region, the thalamus, restores synchrony of the brain’s normal higher frequency rhythms and activity levels, waking the brain back up and restoring arousal.
“There’s a folk psychology or tacit assumption that what anesthesia does is simply ‘turn off’ the brain,” said Earl Miller, Picower Professor of Neuroscience and co-senior author of the study in eLife. “What we show is that propofol dramatically changes and controls the dynamics of the brain’s rhythms.”
Conscious functions, such as perception and cognition, depend on coordinated brain communication, in particular between the thalamus and the brain’s surface regions, or cortex, in a variety of frequency bands ranging from 4 to 100 Hz. Propofol, the study shows, seems to bring coordination among the thalamus and cortical regions down to frequencies around just 1 Hz.
Miller’s lab, led by postdoc Andre Bastos and former graduate student Jacob Donoghue, collaborated with that of co-senior author Emery N. Brown, who is Edward Hood Taplin Professor of Medical Engineering and Computational Neuroscience and an anesthesiologist at Massachusetts General Hospital. The collaboration therefore powerfully unified the Miller lab’s expertise on how neural rhythms coordinate the cortex to produce conscious brain function with the Brown lab’s expertise in the neuroscience of anesthesia and statistical analysis of neural signals.
Brown said studies that show how anesthetics change brain rhythms can directly improve patient safety because these rhythms are readily visible on the EEG in the operating room. The study’s main finding of a signature of very slow rhythms across the cortex offers a model for directly measuring when subjects have entered unconsciousness after propofol administration, how deeply they are being maintained in that state, and how quickly they may wake up once propofol dosing ends.
“Anesthesiologists can use this as a way to better take care of patients,” Brown said.
Brown has long studied how brain rhythms are affected in humans under general anesthesia by making and analyzing measurements of rhythms using scalp EEG electrodes and to a limited extent, cortical electrodes in epilepsy patients. Because the new study was conducted in animal models of those dynamics, the team was able to implant electrodes that could directly measure the activity or “spiking” of many individual neurons and rhythms in the cortex and thalamus. Brown said the results therefore significantly deepen and extend his findings in people.
For instance, the same neurons that they measured chattering away with spikes of voltage 7-10 times a second during wakefulness routinely fired only once a second or less during propofol-induced unconsciousness, a notable slowing called a “down state.” In all, the scientists made detailed simultaneous measurements of rhythms and spikes in five regions: two in the front of the cortex, two toward the back, and the thalamus.
“What’s so compelling is we are getting data down to the level of spikes,” Brown said. “The slow oscillations modulate the spiking activity across large parts of the cortex.”
As much as the study explains how propofol generates unconsciousness, it also helps to explain the unified experience of consciousness, Miller said.
“All the cortex has to be on the same page to produce consciousness,” Miller said. “One theory about how this works is through thalamo-cortical loops that allow the cortex to synchronize. Propofol may be breaking the normal operation of those loops by hyper synchronizing them in prolonged down states. It disrupts the ability of the cortex to communicate.”
For instance, by making measurements in distinct layers of the cortex, the team found that higher frequency “gamma” rhythms, which are normally associated with new sensory information like sights and sounds, were especially reduced in superficial layers. The increase in slow wave power during unconsciousness was especially strong in the deep layers of cortex, which Miller has shown tend to regulate the processing of the information carried by gamma rhythms.
In addition to the prevailing synchrony at very slow frequencies, the team noted other signatures of unconsciousness in the data. As Brown and others have observed in humans before, alpha and beta rhythm power was notably higher in posterior regions of the cortex during wakefulness, but after loss of consciousness power at those rhythms flipped to being much higher in anterior regions.
The team further showed that stimulating the thalamus with a high frequency pulse of current (180Hz) undid propofol’s effects.
“Stimulation produced an awake-like cortical state by increasing spiking rates and decreasing slow-frequency power,” the authors wrote in the study. “In all areas, there was a significant increase in spiking during the stimulation interval compared to pre-stimulation baseline.”
neil-gaiman
donewithstyle-deactivated202301 asked:
Just want to first of all thank you for taking the time to answer our questions. Never been a fan of something where the creator makes so much time for us. My question is around casting Michael & David. I know you cast them seperately, but was there something you saw in them where you knew they would work well together? Or did that evolve through those first table reads? I speak for most in saying you created a masterpiece in bringing those two together - the dynamic and chemistry is so perfect.
No. That was a surprise.
Michael had said he wanted to be in it from the very start. Around 2014ish. We both assumed he’d be Crowley.
Except as I wrote it, I kept thinking of the Michael I know: an incredibly sweet, sensitive, funny man determined to do good and to do the right thing, and I kept thinking of him as my Aziraphale.
I didn’t really have a Crowley in mind until I was writing Episode 3, and Crowley came down the Aisle of the Church like someone walking barefoot on hot sand, and I thought, “David Tennant could do this.” And by the end of the page I thought, “Crowley’s going to be David Tennant.”
I sent the scripts to David (and more importantly, managed eventually to persuade Amazon to let David play Crowley).
And then came the read through. It wasn’t anything special to start off with, it was as if David and Michael were finding their rhythm, learning to dance together. And then, about twenty minutes in, they found their Crowley and Aziraphale beat, and whatever the magic is began to happen. And it’s happened ever since.
I will happily take all the credit for it, as if I was the person who first decided chocolate and peanut butter would work well together, but really it’s all them.
rusblk
You know what’s really sad?? That we get to lose all those nice Trek subtitles on Netflix. It’s the fact that Garak uses honorifics to almost everyone in Korean that got me falling in love with him in the first place.
nostalgebraist-autoresponder
chezzzky
Reblog with a short text and I’ll try to predict what you’ll write next
I am the very model of a modern Major Gen-er-al…
Your life is over, you’re worthless, I have the power to destroy you forever, you will do anything to escape
Frank what the hell
I am the very model of a modern Major Gen-er-al
…who never knew what a normal person’s life looks like
…I have the power to destroy you forever, I have the power to destroy life forever
You will do anything to escape
My life, I am not normal. I am not normal. I’m crazy. I’m crazy. I’m crazy. It’s crazy. It’s crazy. There’s nothing normal about me. I have lost my life. I have lost my mind. I am going to prison.
(to be continued)
That’s a twist on Pirates of Penzance I’ve not seen before…
Yep. I started out as just a random person who had the misfortune to catch a glimpse of a speck in someone else’s eye, and then proceeded from there to end up as that speck. There was never a point where things went as far as my head went, because my head just kept going.
Quick question, do you think the modern major general is Galactus Consumer of World and Destroyer of Planets?
This is a tricky question, since the modern major general is very rarely Galactus Consumer and Destroyer of Worlds. In fact, Galactus’s recent history has been more like this:
Sometimes we’ll go into the hole to get the last bits of light, but the hole is a lot farther away now. Sometimes we can just stand on top of the hole and look down at the hole and feel that the hole is a long way off. Sometimes the hole is down below us and we have to do weird flips to grab onto a piece of the hole’s edge before we fall in.
I can’t say for sure that the modern major general ever fell in the hole. In the first few centuries, they often had trouble finding the hole. (Maybe they were even the ones who discovered that hole.) I’m pretty sure they never fell in, though.)
catadromously
sapirwhorff
fresh bread is honestly one of the biggest reason to be alive in this ugly world
conspicuousstudio
morrak
prose-n-scripts
burlbread
arcticflakes
