A classic case of Brain freeze
17 Mar 2010 by Evoluted New Media
Three-dimensional images of structures involved in communication in the brain have been obtained using a novel technique that cools cells so quickly that their biological structures can be frozen while fully active.
Three-dimensional images of structures involved in communication in the brain have been obtained using a novel technique that cools cells so quickly that their biological structures can be frozen while fully active.
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3D tomography electronic synapses: synaptic vesicles (yellow), cell membrane (purple), connectors between vesicles (red), filaments that anchor the vesicles to the cell membrane (blue), microtubule (dark green), material synaptic space (light green) and postsynaptic density (orange). Credit: Fernandez-Busnadiego et al. |
Electron cryotomography is a new technique based on ultra-fast freezing of cells, and has enabled scientists at the Max Plank Institute of Biochemistry to observe 3D images of synapses, the cellular structure in which communication between neurons take place.
Researchers focussed on the tiny vesicles – measuring around 40nm in diameter – which transport and release neurotransmitters from presynaptic terminals.
“It is possible to observe the huge range of filamentous structures that are within the presynaptic terminal and interact directly with the synaptic vesicles, as well as to learn about their crucial role in responding to the electrical activity of the brain,” said Rubén Fernández-Busnadiego, physicist and lead author of the study.
During synapsis, a presynaptic cell – an emitter – releases neurotransmitters to a recipient, post-synaptic one. This generates an electrical impulse within the recipient, and allows nervous information to be transmitted. Filaments connect tiny vesicles within the cell to each other, and to the active area, the part of the cellular membrane where neurotransmitters are released.
Fernández-Busnadiego says these filaments act as barrier – they block the free movement of vesicles, keeping them in their position until an electrical impulse arrives – as well as determining the ease with which they will fuse with the membrane.
During electron cryotomography, the cells are vitrified – frozen so fast that water inside them cannot crystallise and remains in a solid state. This makes it possible to obtain 3D images of inside cells and minimise changes to their structure. Samples – which are maintained at -140°C – can be viewed using specially-equipped microscopes.
