REYIS OF SUNSHINE

infinity-imagined:

The Hippocampus

cannot believe this is what i’m studying. it looks infinitely more captivating here than in the dull pages of my textbook. 

ilovecharts:

Your Brain In Love

Also: http://www.youtube.com/watch?v=WAigCKiqYvw

:)  

ohyeahdevelopmentalbiology:

itllbejustastory:

Why don’t our arms grow from the middle of our bodies? The question isn’t as trivial as it appears. Vertebrae, limbs, ribs, tailbone … in only two days, all these elements take their place in the embryo, in the right spot and with the precision of a Swiss watch.

During the development of an embryo, everything happens at a specific moment. In about 48 hours, it will grow from the top to the bottom, one slice at a time — scientists call this the embryo’s segmentation. “We’re made up of thirty-odd horizontal slices,” explains Denis Duboule, a professor at EPFL and Unige. “These slices correspond more or less to the number of vertebrae we have.”

Every hour and a half, a new segment is built. The genes corresponding to the cervical vertebrae, the thoracic vertebrae, the lumbar vertebrae and the tailbone become activated at exactly the right moment one after another. “If the timing is not followed to the letter, you’ll end up with ribs coming off your lumbar vertebrae,” jokes Duboule. How do the genes know how to launch themselves into action in such a perfectly synchronized manner? “We assumed that the DNA played the role of a kind of clock. But we didn’t understand how.”

When DNA acts like a mechanical clock

Very specific genes, known as “Hox,” are involved in this process. Responsible for the formation of limbs and the spinal column, they have a remarkable characteristic. “Hox genes are situated one exactly after the other on the DNA strand, in four groups. First the neck, then the thorax, then the lumbar, and so on,” explains Duboule. “This unique arrangement inevitably had to play a role.”

The process is astonishingly simple. In the embryo’s first moments, the Hox genes are dormant, packaged like a spool of wound yarn on the DNA. When the time is right, the strand begins to unwind. When the embryo begins to form the upper levels, the genes encoding the formation of cervical vertebrae come off the spool and become activated. Then it is the thoracic vertebrae’s turn, and so on down to the tailbone. The DNA strand acts a bit like an old-fashioned computer punchcard, delivering specific instructions as it progressively goes through the machine.

“A new gene comes out of the spool every ninety minutes, which corresponds to the time needed for a new layer of the embryo to be built,” explains Duboule. “It takes two days for the strand to completely unwind; this is the same time that’s needed for all the layers of the embryo to be completed.”

This system is the first “mechanical” clock ever discovered in genetics. And it explains why the system is so remarkably precise.

…

The Hox clock is a demonstration of the extraordinary complexity of evolution. One notable property of the mechanism is its extreme stability, explains Duboule. “Circadian or menstrual clocks involve complex chemistry. They can thus adapt to changing contexts, but in a general sense are fairly imprecise. The mechanism that we have discovered must be infinitely more stable and precise. Even the smallest change would end up leading to the emergence of a new species.”

(via From blue whales to earthworms, a common mechanism gives shape to living beings)

This is why developmental biology (and evolution and molecular biology and everything) is awesome.

LOVE seeing the two models i studied, the two DEVELOPMENTAL models i studied, being examined in the same infographic :] <3 

best feeling. 

sciencecenter:

Brainwave delay makes rats feel teleported

A bit of a long post, but definitely worth a read.

Snuffling around in a Plexiglas box that it knows well, a black and white rat catches a whiff of chocolate cookies. It scampers toward them—but suddenly, it finds itself teleported into another, equally familiar box. One could hardly blame the poor rat for being confused and disoriented for at least a fraction of a second, and researchers have now figured out why: cells in the memory center of its brain compete over where it is for exactly one-eighth of a second.

The “teleportation” effect in rats is similar to the momentary disorientation you feel when elevator doors open and you step out onto the wrong floor. It occurs because the place you expect to see and the place you actually do are “mutually exclusive,” says Edvard Moser, a neuroscientist at the Norwegian University of Science and Technology in Trondheim. Normally, the brain orients itself gradually as you move. The hippocampus, the brain’s memory center, contains neurons known as place cells, which record both your environment and your movement within it in order to form memories that ensure you always know where you are. To update the brain on your position, place cells fire in a rhythm called a theta oscillation, which repeats itself every 125 milliseconds and is especially prominent when you’re moving.

To teleport rats, Edvard Moser and his wife, neuroscientist May-Britt Moser, built two rat boxes connected by a tunnel. One box had a circle of white light-emitting diodes shining up through the clear floor, and the other had a row of green LEDs around the ceiling. The researchers let a rat run back and forth between the two boxes and forage for food until it became familiar with both. They also implanted an electrode array into the rat’s hippocampus and recorded firing patterns from individual neurons while the rat was in each box.

Then the researchers played a mean trick. They put the rat into the white box and placed some cookie crumbles at one end. While the rat was running toward the treat, they switched the light pattern, fooling the rat into thinking it was suddenly in the green box.

The rat still managed to find its cookies, but when the researchers looked at the recordings from the place cells, they saw a war going on. At the moment of “teleportation,” one group of cells was firing with the pattern that it had used in the white box, but another group fired with the pattern corresponding to the green box. The neurons sorted it out eventually: Within 125 milliseconds, they were all firing together, which is the amount of time that a theta cycle takes to complete, the researchers report online today in Nature. The fact that the two distinct patterns stuck around to fight it out rather than slowly drifting from one pattern to the other suggests that the brain puts memories into discrete, 125-millisecond packages, preventing itself from mixing them up.

ofmiceandbren:

This is someone dying while having an MRI scan. Before you die, your brain releases tons and tons of endorphins that make you feel a range of emotions. Tragically beautiful.

Every time I just watch it for so long.

all of us are the same. i hope that the mice feel the same rush of endorphins in the least painful way. this is probably what “life flashing before my eyes” looks like.

houseofmind:

fuckyeahbiomedicina:

Chemical synapses are specialized junctions through which neurons signal to each other and to non-neuronal cells such as those in muscles or glands.

Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie perception and thought. They allow the nervous system to connect to and control other systems of the body. At a chemical synapse, one neuron releases a neurotransmitter into a small space (the synapse) that is adjacent to another neuron.

Neurotransmitters must then be cleared out of the synapse efficiently so that the synapse can be ready to function again as soon as possible. The adult human brain is estimated to contain from 1014 to 5 × 1014 (100–500 trillion) synapses. Every cubic millimeter of cerebral cortex contains roughly a billion of them.[2] The word “synapse” comes from “synaptein”, which Sir Charles Scott Sherrington and colleagues coined from the Greek “syn-” (“together”) and “haptein” (“to clasp”).

Chemical synapses are not the only type of biological synapse: electrical and immunological synapses also exist. Without a qualifier, however, “synapse” commonly means chemical synapse.

Thought this post was adequate, even though I know most of you are familiar with chemical synapses. Maybe it can serve as a quick recap, considering that I’ve posted information related to chemical synapses and aspects of neurotransmission. I’m planning to make a post on electrical synapses later. 

the beauty of the human mind.