Ephaptic coupling of cortical neurons. Article (PDF Available) in Nature Neuroscience 14(2) · February with Reads. Request PDF on ResearchGate | Ephaptic Coupling of Cortical Neurons: Possible Contribution of Astroglial Magnetic Fields? | The close. Yet the extracellular field activity feeds back onto the electrical potential across the neuronal membrane via ephaptic coupling (Jefferys et al.
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This means of communication, called ephaptic coupling, results when the electric field produced by one neuron silences its neighbor, instead of sending neurotransmitters across a synapse.
In the antennae of Drosophila melanogasterolfactory neurons are bundled into fluid-filled hairs called sensilla. Each sensillum contains two to four neurons, couplimg are all tuned to different smells and grouped in specific ways.
When Su exposed flies couplihg a steady stream of methyl hexanoate, the A neuron fired continuously. If she wafted a brief burst of 2-heptanone, the B neuron spiked, and the A neuron suddenly shut down.
Ephaptic coupling in cortical neurons
cohpling The opposite also happened—a brief burst of dortical in A silenced the steady activity of B. Su found the same interactions in four other types of sensilla in the fruit fly, as well as one in the malarial mosquito Anopheles gambiae.
Despite these clear interactions, neurons within a sensillum do not share any synapses. Su confirmed this by showing that the neighboring neurons can inhibit each other even after a dose of synapse-blocking chemicals, even if their spiking patterns do not coordinate, and even if the antennae are severed, cutting off contact from any central neurons.
Instead of synapses, the neurons are probably communicating via the fluid that surrounds them. When one fires, it creates an electric field that directly changes the flow of ions through the other and shuts down its electrical activity. Although this ephaptic coupling has been seen in the cerebellum of rats, within a group of neurons called Purkinje cellsno one knew what effect it had. Their vinegar neuron, while severed from the brain, could still inhibit its neighboring carbon dioxide neuron.
Neurons Talk Without Synapses | The Scientist Magazine®
When both chemicals were in the air, the flies were no longer repelled by carbon dioxide. According to the authors, these responses could be useful to flies, which might be swamped by some local odor and need to detect faint hints of a new chemical blowing on the wind.
For years, scientists believed that the brain is responsible for integrating the responses of different neurons, which individually detect the presence of different chemicals.
The same thing might happen in humans too. Does ephaptic coupling happen when we eat and drink? Carlson also thinks that the discovery has practical value, as disease-carrying and crop-destroying insects use their sense of smell to find hosts and food.
New Cortical Neuron Types. Getting Synapses Ready to Fire.