Spinal Ia interneuron
From NeuronBankWiki
Spinal Ia is a inhibitory spinal interneuron found in Humans and other mammals.
The Spinal Ia Interneuron is found in the spinal cord. It recieves monosynaptic input from one agonist muscle and then sends monosynaptic output to an atagonist muscle. [1] The Ia Interneuron is involved with locomotion of mammals, more specifically it is involved with the muscle movement. It is achieved by the interactions between it and Renshaw Cells. [3]
Neuronal Type: Spinal Interneuron
Contents |
Anatomy
The Cell body of the Ia interneuron is located inside the spinal cord in the ventral horn of the spinal cord. There are two types of these cell types in the body. One is of course the Ia Interneuron while the second one is the Ib Interneuron. [1 ]
Molecular profile
The neurotransmitter is believed to be glycine.[1] Another possible chemical involved is GABA although there has been no hard data to indicate this as truth. [1]
Physiology
This particular cell type has a special joint in which the cell interacts with the muscle afferent. The antagonist and agonist work on a joint that prevents them from being activated simultaneously. [1 ] It is silenced by the ventral root stimulation [1 ]
Synaptic Connections
Synaptic Inputs
The Ia Interneuron recieves its input from the Renshaw neurons. [3 ] Once the Ia interneuron trigger motion setting off a α-motoneurons. [ 1] The connections are vital to an animal's movement.
Synaptic Outputs
The Ia interneurons connect to alpha motor nuerons which stimulate muscle movement. [1 ]
Spiking properties
Due to the nature of the interneuron itself the Ia internueron is silent when not in use. The reason for this silence is to avoid any interference between the antagonist and agonist relationship of the axons. [ 1]
Behavior
This Neuron is involved with the movement of muscles in an animal's body. It works along side the Renshaw Cells which it recieves monosynaptic input from one agonist muscle and then sends monosynaptic output to an antagonist muscle. [1 ] It Is in the ventral horn where the Renshaw makes a synaptic connection with Ia Inhibitory neurons. [ 1] It is believed that the Glycine, a naturally occuring amino acids, is responsible for triggering reciprocal innervation. There is also speculation that GABA may be involved in this process though it has not been proven by any independant research [1 ]. This process is believed to happen around a joint which prevents the agonist muscle and antagonistsmuscles activate simultaneously. [ 1] These messages come directly from the muscle Ia afferents that are located in each muscle. [1]
References
1. Conn, P. Michael. Neuroscience in Medicine. 3rd. Totowa: Humana Press, 2008.
2. Hammar I,Jankowska E. "Modulatory Effects of α1-, α2-, and β-Receptor Agonists on Feline Spinal Interneurons with Monosynaptic Input from Group I Muscle Afferents." J Neurosci. 2003 Jan 1;23(1):332-8.
3. Pratt CA, Jordan LM. "Ia inhibitory interneurons and Renshaw cells as contributors to the spinal mechanisms of fictive locomotion." J Neurophysiol. 1987 Jan;57(1):56-71.
