The Neural Control of Visually Guided Eye Movements
C. Cortical Mechanisms of Visually Guided Saccadic Eye Movements

In summary, electrical stimulation in the lower layers of V1 and V2 produces facilitation, whereas in the upper layers it produces interference. In LIP both of these effects can be obtained in different subregions. In addition, at those sites where cells discharge with fixation, stimulation prolongs fixation time. In the medial and frontal eye fields only facilitatory effects were found. Lastly, in V4 electrical stimulation was ineffective.

The next step in learning more about target selection with eye movements entailed examination of the consequences of local injection of pharmacological agents into various brain areas. To accomplish this, electrodes were devised that enabled us to first record or stimulate and to then inject selected agents. The procedures were simlar to those described with stimulation (see Figures 15 and 16). After establishing the location of the visual or motor field of the neurons two targets were presented with one centered in the field. Data were then collected before, during and after injecting pharmacological agents in minute quantities.