Dendrite - Wikipedia
Dendrites are tree-like extensions at the beginning of a neuron that help . different problems, such as diseases that impact axon myelination. The axon of one neuron, a dendrite of another, and the gap between "Our work suggests that some problems with learning and memory are. Disorders & Issues · Signs, Symptoms, & Effects Of Addiction As neurons grow, their dendrites reach out and make contact with the axons of adjacent neurons.
They can keep splitting off like that. I want to do a fairly reasonable drawing so I'll spend a little time doing that. So these right here, these are dendrites. And these tend to be-- and nothing is always the case in biology. Sometimes different parts of different cells perform other functions, but these tend to be where the neuron receives its signal.
Anatomy of a neuron
And we'll talk more about what it means to receive and transmit a signal in this video and probably in the next few. So this is where it receives the signal.
So this is the dendrite. This right here is the soma. This is the body of the neuron. And then we have kind of a-- you can almost view it as a tail of the neuron. It's called the axon. A neuron can be a reasonably normal sized cell, although there is a huge range, but the axons can be quite long. They could be short.
Sometimes in the brain you might have very small axons, but you might have axons that go down the spinal column or that go along one of your limbs-- or if you're talking about one of a dinosaur's limbs. So the axon can actually stretch several feet. Not all neurons' axons are several feet, but they could be. And this is really where a lot of the distance of the signal gets traveled. Let me draw the axon.
So the axon will look something like this. And at the end, it ends at the axon terminal where it can connect to other dendrites or maybe to other types of tissue or muscle if the point of this neuron is to tell a muscle to do something. So at the end of the axon, you have the axon terminal right there. I'll do my best to draw it like that. Let me label it. So this is the axon.
This is the axon terminal. And you'll sometimes hear the word-- the point at which the soma or the body of the neuron connects to the axon is as often referred to as the axon hillock-- maybe you can kind of view it as kind of a lump. It starts to form the axon. And then we're going to talk about how the impulses travel.
Neuron - Wikipedia
And a huge part in what allows them to travel efficiently are these insulating cells around the axon. We're going to talk about this in detail and how they actually work, but it's good just to have the anatomical structure first. This is possible because detailed information is now available on the identity and synaptic connections of the main types of neuron. Results The probabilities of synapses between 7 types of identified spinal neuron were measured directly by making electrical recordings from pairs of neurons.
For the same neuron types, the dorso-ventral distributions of axons and dendrites were measured and then used to calculate the probabilities that axons would encounter particular dendrites and so potentially form synaptic connections. Surprisingly, synapses were found between all types of neuron but contact probabilities could be predicted simply by the anatomical overlap of their axons and dendrites.
How Drugs Affect The Brain
These results suggested that synapse formation may not require axons to recognise specific, correct dendrites. To test the plausibility of simpler hypotheses, we first made computational models that were able to generate longitudinal axon growth paths and reproduce the axon distribution patterns and synaptic contact probabilities found in the spinal cord.
To test if probabilistic rules could produce functioning spinal networks, we then made realistic computational models of spinal cord neurons, giving them established cell-specific properties and connecting them into networks using the contact probabilities we had determined.
- Frontiers for Young Minds
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A majority of these networks produced robust swimming activity. Conclusion Simple factors such as morphogen gradients controlling dorso-ventral soma, dendrite and axon positions may sufficiently constrain the synaptic connections made between different types of neuron as the spinal cord first develops and allow functional networks to form. Our analysis implies that detailed cellular recognition between spinal neuron types may not be necessary for the reliable formation of functional networks to generate early behaviour like swimming.
Background To function properly, nervous systems rely on highly specific synaptic connections between neurons. This specificity is achieved during development by many mechanisms, for example, correct neuronal specification and differentiation, axon path finding, cell recognition and synapse conditioning by neuronal activities.