5

As Virginia Hughes noted in a recent piece for National Geographic’s Phenomena blog, the most common depiction of a synapse (that communicating junction between two neurons) is pretty simple:

External image

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!

You can access the full video of their 3D model here.

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

Incredible and rare micrograph of a synapse 

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. 

read more from Neurons Want Food 

3

Gary Carlson  
Medical and Biological Illustration
[website]

OSTEOCLAST ACTIVITY
Osteoclasts remove excess bone by etching away at the bone surface. When they become overactive, osteoporosis may occur. [source]

ADIPOGENESIS
Adipocytes, or fat cells, greatly increase in size over time as lipid droplets accumulate within the cytoplasm.  [source]

SYNAPTIC JUNCTION
Schematic representation of neurotransmitters crossing between neurons showing the action of a drug for treating Alzheimer’s disease.[source]

Unutarnji pismonose / Internal letter-carriers
by ~strybor  [Croatia]

ALLEGORICAL SCIENTIFIC ILLUSTRATION
SYNAPSES & NEUROTRANSMITTERS

  • The cages are pre-synaptic vesicles,
  • freeing the bird-neurotransmitters, which,
  • when they position themselves on the branches - receptors,
    activate the trees which then
  • make their roots transfer more messages into the neuron’s body.

Scientists Discover the Origin of a Giant Synapse

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.

Continue Reading

2

A new mechanism of synapse elimination

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.