A wide variety of diseases can affect the brain, many of which are caused by bacterial or viral infections. One of the best known of such diseases is meningitis, an acute inflammation of the membranes encasing the brain and spinal cord. Meningitis can be caused by bacteria, viruses, fungi, or other organisms that enter the bloodstream. Symptoms of meningitis often include headache, a stiff neck, and sensitivity to light, as well as muscle pain, chills, and fever. Convulsions may develop as a complication of meningitis and the condition can be fatal if not treated in a timely manner. Viral forms of meningitis are the most common and they tend to be less severe than bacteria-induced meningitis.

A horizontal section of rat brain was immunofluorescently labeled for phosphorylated neurofilaments with mouse anti-NF-P antibodies followed by goat anti-mouse secondary antibodies conjugated to Alexa Fluor 488. Neurofilaments are specialized intermediate filaments solely found in neurons, especially in their axons. In addition, glial fibrillary acidic protein, which is expressed in various astroglia and neural stem cells, was targeted with rabbit anti-GFAP antibodies visualized with goat anti-rabbit secondary antibodies conjugated to Alexa Fluor 568. Cell nuclei were labeled with the popular nuclear counterstain Hoechst 33342. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.