Why Neurons have thousands of synapses
What I learned
- dendrites are connected to many synapses
- each neuron has roughly 7,000 synapses
- there are 3 types of dedrites
- proximal (feedforward)
- represent the receptive field of a neuron
- reside in layer 1 in a cortical column
- 20 neurons are enough to trigger an action potential
- basal (prediction)
- apical (feedback from the synapses, also prediction)
each of them delivers another input, leading to small depolarizations, but basal and apical not always to an action potential.
These depolarizations are predictions. The neurons with a prediction fire first and inhibit surrounding neurons.
- proximal (feedforward)
In a cortical cellular layer all neurons activate when an unknown (unpredicted) stimulus arrives. The more often this happens the more likely one neuron will be first.
Therefore you have less activations in the future and many ways to code information in a column.
The combinations of neuron activity lead to hundreds of possibilities to code information in a single column.
Why do they have so many synapses and dendrites?
With many synapses closing onto one dendrite (40 or so), the dendrite can make sure it only responds to the particular pattern which evokes an action potential. It reduces face positives by a sheer number of synapses.
Because in general, only 2% of all cells are active simultaneously, making it highly unlikely to evoke an action potential without the demanded sequence.
evaluation
easy to read. You notice that Jeff Hawkins is a book author. And also very interesting about how neurons learn. I love it.
see also
Tags: neurobiology science
Superlink: 051 ☣Neurobiology 050 🧠Neuroscience
Neuron Cell
Synapse
Dendrites
|Hawkins, J., & Ahmad, S. (2016). Why neurons have thousands of synapses, a theory of sequence memory in neocortex. Frontiers in neural circuits, 10, 174222.|
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Created: 13-09-24 21:08