• The dark matter of the brain

    From ScienceDaily@1:317/3 to All on Tue Apr 5 22:30:38 2022
    The dark matter of the brain
    Electrical synapses - omnipresent and yet hardly explored

    Date:
    April 5, 2022
    Source:
    Max-Planck-Gesellschaft
    Summary:
    They are part of the brain of almost every animal species, yet
    they remain usually invisible even under the electron microscope.



    FULL STORY ==========================================================================
    They are part of the brain of almost every animal species, yet they remain usually invisible even under the electron microscope. "Electrical synapses
    are like the dark matter of the brain," says Alexander Borst, director
    at the MPI for Biological Intelligence, in foundation (i.f). Now a team
    from his department has taken a closer look at this rarely explored
    brain component: In the brain of the fruit fly Drosophila, they were
    able to show that electrical synapses occur in almost all brain areas
    and can influence the function and stability of individual nerve cells.


    ========================================================================== Neurons communicate via synapses, small contact points at which chemical messengers transmit a stimulus from one cell to the next. We may remember
    this from biology class. However, that is not the whole story. In addition
    to the commonly known chemical synapses, there is a second, little-known
    type of synapse: the electrical synapse. "Electrical synapses are much
    rarer and are hard to detect with current methods. That's why they have
    hardly been researched so far," explains Georg Ammer, who has long been fascinated by these hidden cell connections. "In most animal brains, we therefore don't know even basic things, such as where exactly electrical synapses occur or how they influence brain activity." An electrical
    synapse connects two neurons directly, allowing the electrical current
    that neurons use to communicate, to flow from one cell to the next
    without a detour. Except in echinoderms, this particular type of synapse
    occurs in the brain of every animal species studied so far. "Electrical synapses must therefore have important functions: we just do not know
    which ones!" says Georg Ammer.

    Distribution in the brain To track down these functions, Ammer and his
    two colleagues, Rene'e Vieira and Sandra Fendl, labelled an important
    protein building block of electrical synapses. In the brain of fruit
    flies, they were thus able to show that electrical synapses do not occur
    in all nerve cells, but in almost all areas of the brain. By selectively switching off the electrical synapses in the area of visual processing,
    the researchers could show that the affected neurons' reaction to certain stimuli is much weaker. Furthermore, without electrical synapses, some
    nerve cell types became unstable and began to oscillate spontaneously.

    "The results suggest that electrical synapses are important for diverse
    brain functions and can play very different functional roles, depending on
    the type of neuron," Ammer summarizes. "These synapses should therefore
    also be integrated in connectome studies." The connectome is a map of
    all neurons and their connections in a brain or brain area. Often, this information is reconstructed from electron microscope images -- where electrical synapses are largely invisible. How these can be integrated
    into connectome investigations and what other secrets electrical synapses
    hold, is subject for further studies.


    ========================================================================== Story Source: Materials provided by Max-Planck-Gesellschaft. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Georg Ammer, Rene'e M. Vieira, Sandra Fendl, Alexander
    Borst. Anatomical
    distribution and functional roles of electrical synapses in
    Drosophila.

    Current Biology, 2022; DOI: 10.1016/j.cub.2022.03.040 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220405143540.htm

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