Signal molecules leave one neuron from that bulby thing, float across a gap, and are picked up by receptors on the other neuron. In this way, information is transmitted from cell to cell … and thinking is possible.
But thanks to a bunch of German scientists - we now have a much more complete and accurate picture. They’ve created the first scientifically accurate 3D model of a synaptic bouton (that bulby bit) complete with every protein and cytoskeletal element.
This effort has been made possible only by a collaboration of specialists in electron microscopy, super-resolution light microscopy (STED), mass spectrometry, and quantitative biochemistry.
says the press release. The model reveals a whole world of neuroscience waiting to be explored. Exciting stuff!
Credit: Benjamin G. Wilhelm, Sunit Mandad, Sven Truckenbrodt, Katharina Kröhnert, Christina Schäfer, Burkhard Rammner, Seong Joo Koo, Gala A. Claßen, Michael Krauss, Volker Haucke, Henning Urlaub, Silvio O. Rizzoli
Neuron cell body (purple) with numerous synapses (blue) magnified 80,000x under a scanning electron microscope.
Everone talks about synapses even though some seem to use it to sound cool without actually knowing what it is. So for those persons (and everyone willing to become a bit more educated), here’s a simple explanation.
Information from one neuron flows to another neuron across a synapse. The synapse contains a small gap separating neurons.
The synapse consists of:
a presynaptic ending that contains neurotransmitters, mitochondria and other cell organelles,
a postsynaptic ending that contains receptor sites for neurotransmitters,
a synaptic cleft or space between the presynaptic and postsynaptic endings.
At the synaptic terminal (the presynaptic ending), an electrical impulse will trigger the migration of vesicles containing neurotransmitters toward the presynaptic membrane. The vesicle membrane will fuse with the presynaptic membrane releasing the neurotransmitters into the synaptic cleft.
Scientists to simulate human brain inside a supercomputer
Scientists at its forerunner, the Switzerland-based Blue Brain Project, have been working since 2005 to feed a computer with vast quantities of data and algorithms produced from studying tiny slivers of rodent gray matter.
Last month they announced a significant advancement when they were able to use their simulator to accurately predict the location of synapses in the neocortex, effectively mapping out the complex electrical brain circuitry through which thoughts travel.
Henry Markram, the South African-born neuroscientist who heads the project, said the breakthrough would have taken “decades, if not centuries” to chart using a real neocortex. He said it was proof their concept, dubbed “brain in a box” by Nature magazine, would work.
Now the team are joining forces with other scientists to create the Human Brain Project. As its name suggests, they aim to scale up their model to recreate an entire human brain.
It is a step that will need both a huge increase in funding and access to computers so advanced that they have yet to be built.
If their current bid for €1 billion ($1.3 billion) of European Commission funding over the next 10 years is successful, Markram predicts that his computer neuroscientists are a decade away from producing a synthetic mind that could, in theory, talk and interact in the same way humans do.
Humans and most mammals can determine the spatial origin of sounds with remarkable acuity. We use this ability all the time—crossing the street; locating an invisible ringing cell phone in a cluttered bedroom. To accomplish this small daily miracle, the brain has developed a circuit that’s rapid enough to detect the tiny lag that occurs between the moment the auditory information reaches one of our ears, and the moment it reaches the other. The mastermind of this circuit is the “Calyx of Held,” the largest known synapse in the brain. EPFL scientists have revealed the role that a certain protein plays in initiating the growth of these giant synapses.
Disorder in proper neural circuit formation during development is thought to underlie the pathogenesis of schizophrenia and neurodevelopmental diseases. Neural circuits are shaped by activity-dependent elimination of unnecessary synapses during postnatal development. This process is known as synapse elimination and is widely considered to be a critical step in creating mature neural circuits. Neural activity has been shown to be essential for synapse elimination, but the underlying mechanisms remain largely unknown.
Professor Masanobu Kano and his colleagues at the Graduate School of Medicine have reported that the immediate early gene Arc, one of a class of genes that respond transiently and rapidly to cellular stimuli, mediates activity-dependent synapse elimination in the developing cerebellum. First, they showed that the elevation of Purkinje cell activity in the mouse cerebellum accelerated climbing fiber synapse elimination. Then, they elucidated that the expression of Arc induced by Ca2+ influx into Purkinje cells was crucial for the acceleration of synapse elimination. Furthermore, they demonstrated that Arc is essential for accomplishing synapse elimination by removing the redundant climbing fiber synapses on the cell bodies of Purkinje cells.
Disordered expression of Arc has recently been reported in several mouse models of neurodevelopmental diseases, including Fragile X syndrome and tuberous sclerosis. This study may provide a new approach to unraveling the pathogenesis of such diseases in the light of synapse elimination.
The image above depicts a false-colored cross-section view of a synapse – the junction where signals pass from a neuron to another cell. The green-colored synaptic bouton (button) is a knoblike swelling at the end of a neuronal axon. It’s the megaphone, so to speak, through which a neuron talks to the rest of the world.
In this image, the bouton is surrounded by an insulating glial cell (speckled purple) that bumps up against a muscle fiber, the recipient of neuronal signals.
The thin, dark purple gap between the bouton and fiber is the synaptic cleft. Signal molecules are released by the bouton into this space and taken up by receptors on the receiving cell. Inside the bouton itself are mitochondria (dark blue circles), the power plants of cells, and vesicles (smaller, green circles) filled with yellow neurotransmitters.
In citing their work, the Nobel Prize committee explained that the newly minted laureates had solved the mystery of how cells organize their transport system.
“Each cell is a factory that produces and exports molecules,” wrote the committee in their announcement. “For instance, insulin is manufactured and released into the blood and chemical signals called neurotransmitters are sent from one nerve cell to another. These molecules are transported around the cell in small packages called vesicles. The three Nobel Laureates have discovered the molecular principles that govern how this cargo is delivered to the right place at the right time in the cell.”