Simulation in neurobiology: theory or experiment?

Investigation in neurophysiology usually involves measurements of large population-average signals or small sample recordings. There is an underlying assumption that the observations express activity of large groups of similarly acting neurons that is the result of a bottom-up scenario in which individual cells, via their synaptic interactions, lead to the large scale phenomena. The connection between the levels must be provided by theory, which must also provide the relevant variables for observation. It is suggested that between the experiment and the full theory there is a creative, mixed role for simulation: both experimental and theoretical. A simulation presents complex dynamics and hence is an empirical board for testing theoretical tools, yet its controlled behaviour can make predictions about the biological system.