Focal injections of substances that temporally disable small populations of cells in a particular structure can be used to provide evidence about the functional role of these cells in controlling saccadic eye movements. In these studies the discharge characteristics of cells at the injection site are first established by single-cell recording techniques as the animal performs a variety of saccadic behaviors. Then microliter or smaller amounts of the lesioning substance is then injected at the same site, and the change in saccade performance is recorded. We are currently using lidocaine or muscimol to make reversible lesions in the superior colliculus (SC) in order to effect the production of the curved saccades that we have reported to occur in a visual search paradigm. We also examine target selection biases in a search paradigm following the placement of focal lesions. In another study we have made reversible lesions using muscimol in the nucleus reticularis tegmenti pontis (NRTP). These temporary lesions in NRTP have produced dramatic reductions in saccade accuracy within a sector of directions. The NRTP is known to provide one of the main avenues of communication between both the SC and the frontal eye fields (FEF), and the cerebellum, another structure that is important for the accurate production of saccades. The figure below shows preliminary results in the lesion study of the NRTP.