Interneuron

In the human brain, approximately 20–30% of the neurons in the neocortex are interneurons, and the remaining majority of neurons are pyramidal. Investigations into the molecular diversity of neurons is impeded by the inability to isolate cell populations born at different times for gene expression analysis. An effective means of identifying coetaneous interneurons is neuronal birthdating. This can be achieved using nucleoside analogs such as EdU. Spinal cord • Ia inhibitory interneuron: Found in lamina VII. Responsible for inhibiting antagonist motor neuron. 1a spindle afferents activate 1a inhibitory neuron. • (relay neuron) forms part of a reflex arcIb inhibitory interneuron: Found in lamina V, VI, VII. Afferent or Golgi tendon organ activates it. Cortex • Parvalbumin-expressing interneurons • CCK-expressing interneurons • VIP-expressing interneurons • SOM-expressing interneurons Cerebellum • Molecular layer (basket cells, stellate cells) • Golgi cells • Granule cells • Lugaro cells • Unipolar brush cells Striatum • Parvalbumin-expressing interneurons • Cholinergic interneurons • Tyrosine hydroxylase-expressing interneurons • Calretinin-expressing interneurons • Nitric oxide synthase-expressing interneurons ==Function==

Interneurons in the CNS are primarily inhibitory, and use the neurotransmitter GABA or glycine. However, excitatory interneurons using glutamate in the CNS also exist, as do interneurons releasing neuromodulators like acetylcholine. In addition to these general functions, interneurons in the insect CNS play a number of specific roles in different parts of the nervous system, and also are either excitatory or inhibitory. For example, in the olfactory system, interneurons are responsible for integrating information from odorant receptors and sending signals to the mushroom bodies, which are involved in learning and memory. In the visual system, interneurons are responsible for processing motion information and sending signals to the optic lobes, which are involved in visual navigation. Interneurons are also important for coordinating complex behaviors, such as flight and locomotion. For example, interneurons in the thoracic ganglia are responsible for coordinating the activity of the leg muscles during walking and flying. Interneurons' main function is to provide a neural circuit, conducting flow of signals or information between sensory neurons and motor neurons. == References ==