The supplementary eye field (SEF) of the macaque monkey is commonly thought to be an oculomotor area. This view is seemingly supported by the fact that SEF neurons fire when monkeys prepare to make eye movements, with each neuron firing preferentially before eye movements to targets within a restricted response field. However, planning eye movements involves remembering the locations of targets and deploying attention to those locations. Thus neuronal activity in the SEF may be related to high-order functions accompanying eye movements rather than to the programming of eye movements in itself. To resolve this issue is the aim of the proposed experiments. Monkeys will be trained to perform both a memory guided saccade task (in which they mast plan eye movements to a remembered location) and a spatial working memory task (in which they must remember a location but suppress any tendency to look at it). In the context of each kind of task, they will be trained to process locations as defined with respect to the retina and with respect to reference objects. During task performance, neuronal activity will be monitored in the SEE The data will be analyzed to test the hypothesis that neurons in the SEF represent locations being held in working memory regardless of whether or not those locations are the targets of intended eye movements. The results will clarify the neural mechanisms underlying spatial working memory and will help to explain the nature of behavioral impairments occurring after mum and in cases of neuropsychiatric disorder with frontal lobe involvement.