Is interneuron only found in the CNS? Is there no interneuron in the PNS?

[m25]

Is interneuron only found in the CNS? Is there no interneuron in the PNS?

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[rraidermd]

CNS: Interneurons
PNS: Sensory & motor neurons

Sensory neurons (pns) I touch a hot stove [sends afferent single toward brain] ---> Interneurons (cns) my brain tells me I shouldn't keep my hand there to prevent burn ---> Motor neurons (pns) I lift my hands to prevent further tissue damage [efferent signal response].

 

[El-Rami]

Yup. Remember that interneurons are found within the spinal cord, thus they are part of the CNS. Not all reflex arcs use interneurons (such as patellar reflex) while others do (such as withdrawal reflex). The purpose of reflex arcs is to prevent injury without waiting for the brain to tell you to move your hand from a hot stove or to lift your foot from a nail. The information still reaches the brain by afferent neurons, but the reflex is triggered before that happens.

 

[m25]

Yup. Remember that interneurons are found within the spinal cord, thus they are part of the CNS. Not all reflex arcs use interneurons (such as patellar reflex) while others do (such as withdrawal reflex). The purpose of reflex arcs is to prevent injury without waiting for the brain to tell you to move your hand from a hot stove or to lift your foot from a nail. The information still reaches the brain by afferent neurons, but the reflex is triggered before that happens.

CNS: Interneurons
PNS: Sensory & motor neurons

Sensory neurons (pns) I touch a hot stove [sends afferent single toward brain] ---> Interneurons (cns) my brain tells me I shouldn't keep my hand there to prevent burn ---> Motor neurons (pns) I lift my hands to prevent further tissue damage [efferent signal response].

So interneuron has integrative function that acts either in the brain or the spinal cord?

 

[El-Rami]

As I understand it, the interneurons in the spinal cord interface with afferent (cell body of interneuron is post-synaptic membrane) and efferent (motor neuron cell bodies are the post-synaptic membranes) nerves. The afferent nerves still synapse with their respective higher structures in the CNS.

 

[m25]

As I understand it, the interneurons in the spinal cord interface with afferent (cell body of interneuron is post-synaptic membrane) and efferent (motor neuron cell bodies are the post-synaptic membranes) nerves. The afferent nerves still synapse with their respective higher structures in the CNS.

So are you basically saying that the order they synapse is sensory/afferent--> interneuron--> motor/efferent.
So the sensory/afferent nerves that are synapsing with higher structures in the CNS actually just synapsing to another interneuron? Since out of all 3 types of neuron, only interneuron is located in the CNS while sensor and motor are located in PNS.
And are you saying that interneurons are located both in the brain and spinal cord(which are what CNS is comprised of), or just in the spinal cord?

 

[EverStriving]

All neurons in the brain and spinal cord are interneurons. All neurons in the peripheral nervous system are either afferent or efferent.

 

[jd989898]

Glad I saw this thread lol. Never knew about the distinction between local interneurons and relay interneurons.

 

[lmladdno84]

All neurons in the brain and spinal cord are interneurons. All neurons in the peripheral nervous system are either afferent or efferent.

Are interneurons found in the brain? I thought it was only SC.

 

[lmladdno84]

Are interneurons found in the brain? I thought it was only SC.

Nm, I stand corrected

 

[El-Rami]

Are interneurons found in the brain? I thought it was only SC.

"Inter-" = "Between." There are many neurons that take place in transmitting a neural cascade from one region of the brain to another. Therefore, they are interneurons. If there is one or more neuron between two neurons, it is an interneuron.

 

[TheRelevant]

The term interneuron is a bit convoluted when referring to the brain. Some texts consider all neurons within the brain to be Interneurons. However, in literature, Interneurons are classically referred to inhibitory GABAergic local circuit relay neurons, similar to the ones seen in the spinal cord that coordinate reflex arcs.

 

[El-Rami]

The term interneuron is a bit convoluted when referring to the brain. Some texts consider all neurons within the brain to be Interneurons. However, in literature, Interneurons are classically referred to inhibitory GABAergic local circuit relay neurons, similar to the ones seen in the spinal cord that coordinate reflex arcs.

Yeah this is the source of confusion for many people. I believe for the former, they take a literal interpretation of the word "interneuron" as a neuron that is between other neurons.