Depressive episodes as reversible mental states are likely to be associated with equally reversible brain states. These can be examined with a variety of functional imaging methods using repeated measures designs. Studies using such an approach are reviewed. Changes in medial frontal, and in particular, cingulate cortex are reported in a majority of studies. Similarities and differences between different study results are discussed on the background of the functional neuroanatomy of the anterior cingulate, taking into account a variety of neurotransmitter systems. It is concluded that neuroimaging techniques are starting to equip us to conceptualize functional changes in the limbic loop containing the anterior cingulate as the common denominator of change and therapy effects in depressive states.