Bill Gibson, School of Mathematics and Statistics, University of Sydney Most modeling of brain function concentrates on neurons, with emphasis on their connectivity and electrical activity. However, the brain and nervous system contain another class of cells, the glia, that actually outnumber neurons. These cells were first observed over a century ago, but were thought to be mainly a support system for the much more important neurons. This view is now changing, with the increasing realization that glia, and in particular the type known as astrocytes, form an important communication system in their own right and are responsible for controlling many aspects of brain function. Indeed, one author has suggested that "science has missed one-half of the brain". This talk will survey modeling work involving glial cells that I have been involved in over the past 5 years, in collaboration with Max Bennett and Les Farnell. Topics to be covered are signal transmission in artificially constructed astrocyte networks, the pathway relating neural activity to changes in blood flow in the cortex (of significance in brain imaging), the role astrocytes play in cortical spreading depression (related to migraine and stroke damage) and the involvement of spinal cord astrocytes and microglia in neuropathic (persistent) pain.