p.p1 neurons is that they are able to carry

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In the scientific community there is much debate about how NG2 cells communicate with the surrounding neuronal community. NG2 cells are currently believed to be glial cells that eventually develop into oligodendrocytes or oligodendrocyte precursor cells (OPC’s) (Bergles et al., 2000). OPC and NG2 can be used interchangeably  During gestation and shortly after birth mammals develop oligodendrocytes that will myelinate axons (Bergles et al., 2000). OPC’s are a stellate shape with many thin branches that elongate from a small soma (Bergles et al., 2000). Previous research has shown that activation of glutamate receptors on OPC’s leads to a decrease in total mature oligodendrocytes eventually leading to over excitation and finally to cell death (Bergles et al., 2000). Bergles et al., 2000 examined how glutamate reached ?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors found on the OPC’s in the mammalian hippocampus by whole cell patch-clamping techniques to view afferent excitatory axonal responses.
Bergles et al., 2000 found that when electrical currents were mediated by AMPA receptors they were reversibly blocked by calcium. This showed that OPC’s were dependent on calcium. Bergles et al., 2000 postulated that afferent glutamatergic axons are associated with calcium in order to communicate with OPC. Through patch-clamp techniques Bergles et al., 2000 was also able to find that CA3 pyramidal neurons excite OPC’s and CA1 pyramidal neurons. These findings were present in both adult and young models of mammals. A second synaptic relationship between surrounding neurons and OPC’s became apparent and Bergles speculated that OPC’s have tight synaptic clefts that are able to fire quickly and receive up to 800 synapses within a set amount of time. A key feature of neurons is that they are able to carry an action potential (Biase et al., 2010). This finding could change the definition of a NG2/OPC as they are typically believed to be glial cells. 
In another study done by Biase et al., 2010 looking at NG2 cells researchers used mice models to look at brain slices of the hippocampus, corpus callosum, cerebellar white matter and cerebellar molecular layer for changes in physiological properties as the mice aged. Previous evidence showed that NG2 cells were found in grey and white matter and as Bergles research showed, were able to carry an action potential (Biase et al., 2010). To build on Bergles research, Biase et al., 2010 examined which stages of mammalian development do NG2 cells communicate with surrounding neurons. 
Biase et al., 2010 found that all NG2 cells had sodium channel mediated currents although they were unable to fire an action potential when mice were mature. Younger mice models were able to fire action potentials in grey and white matter within the first week after birth following the development of glutamatergic synapses (Biase et al., 2010). This finding competed with Bergles’s previous finding meaning that there is still debate about rather NG2 cells are able to carry action potentials into adulthood. Interestingly, NG2 cells were still differentiating in the adult brain even thought they were not firing action potentials. Biase et al., 2010 found that as the mice aged their NG2 cells experienced a rapid decrease in synapses, AMPA and NMDA receptors. Other findings from Biase’s study showed that early NG2 cells had a higher potassium resting conductance which is potentially why NG2 cells are not always able to carry an action potential when they are older. NG2 cells were found to have sodium channels and synapses specifically within the corpus callosum although, this may not be true for all areas of the cerebral cortex where NG2 cells can be found (Biase et al., 2010). Biase et al., 2010 states that NG2 cells may communicate through paracrine hormones from surrounding neurons.
More recently Nagy et al., 2017 performed an experiment to examine OPC communication based on surrounding neural firing patterns to the OPC, specifically in the corpus callosum. Nagy  et al., 2017 investigated how axon stimulation would change turnover to mature oligodendrocytes, neurotransmitter release, proliferation and differentiation of OPC’s. Researchers found that glutamate was released in vesicles by OPC’s and that after electrical stimulation was withdrawn there was a short spike in glutamate release to the surrounding neural environment. This finding coincides with Biase’s finding that OPC’s may communicate through paracrine hormones. Nagy et al., 2017 also found that OPC’s  intracellular ion concentrations of sodium and calcium were expressed and played a key role in OPC’s ionic communication. Nagy speculated that proliferation, turnover and migration is dependent on intracellular concentrations of ions as different firing patterns changed how the OPC’s matured. Finally Nagy et al., 2017 concluded that axonal-OPC synapses may activate a variety of enzymatic pathways within the OPC. Previous research has shown that oligodendrocyte maturation is affected by ATP, adenosine, neural growth factors and nitric oxide (Nagy et al., 2017) These factors are brought about by downstream pathways which are stimulated by different firing patterns from surrounding neurons (Nagy et a., 2017).  Certain firing patterns had better outcomes then others as 5 Hz caused more differentiation in OPC populations then 25 Hz or 300 Hz of stimulation (Nagy et al., 2017). 
Future research in NG2 cells has many directions. NG2 cells have been found to respond to the surrounding neuronal community differently depending on where they are located in the cerebral cortex. Also it appears that NG2/OPC’s have different responses to stimulus as the oligodendrocyte and mice matures. Since these cells eventually turn into myelinating cells (oligodendrocytes) future research could go into the direction of demyelinating disorders or when one experiences ischemia. Research is still unsure why some NG2 cells lose their receptors as they age and others don’t. Finally research could look at neurotransmitters affects on NG2/OPC’s.

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