Neurons, Glial Cells and Imaging

Scientists at the European Molecular Biology Laboratory have investigated how embryonic stem cells become mature nerve cells. They assessed the complex interplay of molecules during the differentiation process. Consequently, new insights into the role of a protein called SOX2 in neurons emerged. This protein is expressed by a gene, SOX2, located on chromosome 3 in humans. This gene is a sex-determining Yrelated HMG box2 and serves as a marker for neural stem and progenitor cells [1]. Progenitor stem cells become neurons and glial cells. The ratio of glia to neurons in the human brain is 10:1. This suggests that glial cells play significant roles in cognitive functions. Glial cells of CNS are divided into microglia and macroglia. The microglia are macrophage-like cells, which function as a phagocyte. Macroglia consist of astrocytes and oligodendrocytes. Oligodendrocytes act as CNS equivalent to myelinating Schwann cells in the peripheral nervous system (PNS).

Neuroimaging is a branch of medical imaging that focuses on the brain. Among all imaging techniques, magnetic resonance imaging (MRIs) and MEGs (Magnetoencephalographs) are favorites of medical doctors. MRI has two variants: functional MRI and structural MRI. In this chapter, both of them are discussed. Detection and monitoring of the progression of neurodegenerative diseases are performed with MEG by analyzing neural complexity and the Grassberger-Procaccia correlation dimension. Lempel-Ziv complexity is a better option. Positron emission tomography (PET) is a useful procedure to measure the metabolic activity of the cells of body tissues. PET helps monitor biochemical changes in the body. Electroencephalography is used to characterize states of consciousness of the brain. EEG is not discussed in the present chapter since the aim of the chapter is not to present all neuroimaging techniques but to cover a select few depending on the author’s own background and experience.