- Myelin acts as an insulator.
Neuron action potential spike
Types of neurons
According to morphology
Neurons in the Cortex can be classified as belonging to two types:
- Pyramidal neurons – excitatory.
- Have an apical dentrite (from the apex) which shoots upwards to the surface of the cortex. It branches little until it reaches the cortex, where it branches a lot (cortical tuft).
- Many branching dentrites from the base of the neuron, which only connect to the local region
- An axon that most often goes down into the white matter, but sometimes it has a lateral branch that reaches to another part of the cortex.
- The synapses it forms (from axon) are excitatory (asymmetric).
- The synapses it receives are mostly inhibtory when in its body or branches, but excitatory at the far ends of the dentrites.
- As most excitatory neurons, they have a many Neural spines
- Stellate neuron
- Axons and dendrites reach only local regions of the cortex where they are located.
- As for pyramidal neurons. The synapses it receives are mostly inhibtory when in its body or branches, but excitatory at the far ends of the dentrites.
- Main types:
- Spiny stellate neurons. Have neural spines and are excitatory.
- Smooth stellate neurons. Don't have neural spines and are inhibitory.
- Sparsely spiny stellate neurons. Have only sparse spines, and can be excitatory or inhibitory.
- A particular type (sometimes considered separate) is the Martinotti cell, situated at the depth of the cortex, and whose axon grows toward the cortical surface, extending few collaterals on its way up, but branching out profusely under the cortical surface, where it makes synapses on the apical dentricit tufts of the pyramidal cells.
- Chandelier cells. Chandelier neurons synapse exclusively to the axon initial segment of pyramidal neurons, near the site where action potential is generated.
- Basket cells
One can of course, just divide them into
Synapse
Neurotransmitter
Symmetric or inhibitory synapses
Asymmetric or excitatory synapses