This can lead to allodynia, which is thought as pain because of a stimulus that does not normally provoke pain. Nerve injury activates a receptor on microglia, called P2X4, which, in turn causes the release of a molecule called Brain Derived Neurotrophic Element, or BDNF. BDNF offers been shown to possess a role in learning in the engine cortex, where its launch results in enhanced engine functionality. Dr. Salter proposes that whenever microglia-derived BDNF facilitates the output of the dorsal horn pain-transmitting network, the result is enhanced pain.This is an ideal disease for a screening check. The technique used to screen for this disease is the Papanicolaou smear .The Pap smear is conducted by viewing the cervix through a speculum and using an instrument called an Ayer speculum to gently scrape the surface of the cervix. This leaves a residue of cells on the spatula. These cells are then spread over a microscope slide and fixed with a particular chemical. The slides are then viewed under a microscope. All females who are sexually energetic, or higher age 18 years, must have a regular Pap smear. How they should have these is available to some debate regularly. Most obstetrician-gynecologists in the United States recommend a Pap test every year.