to the frontal and oculomotor cortex. Hikosaka and Wurtz devoted four papers to "the visual and oculomotor functions of the monkey substantia nigra pars reticulata". This is largely involved in orientation and the control of eye movements in stabilisation of gaze and in saccades. Pars reticulata sends inhibitory projections to the superior colliculus, inhibiting eye movement, and this inhibition is 'lifted', i.e. the projecting neurons cease firing, during saccades. Pathology The function of the neurons of the pars compacta (not reticulata) is profoundly changed (60% of Dopamine secreting neurons, 80% decrease in dopamine in striatum) in parkinsonism and epilepsy. These changes are thought to be mostly secondary to pathology elsewhere in the brain, but may be crucial to understanding the generation of the symptoms of these disorders. References Basal ganglia Midbrain