TABLE 1.

Distribution of SNr and SC neurons

	Hemisphere
	Crossed	Uncrossed
A. SNr neurons
Visual	2	4
Visual delay	2	1
Visual delay saccade	15	10
Visual saccade	1	5
Saccade	0	2
Total	20	22
B. SC neurons
Visuomotor (burst)	2	2
Buildup (prelude)	18	20
Total	20	22
C. Response field

Overlapped		Nonoverlapped/Opposite
Crossed	Uncrossed	Crossed	Uncrossed
0/20	18/22	20/20	4/22

The response characteristics of the SC and SNr neurons were determined as described in methods. SNr neuron types are listed and the numbers of each type indicated under the columns labeled “Crossed” or “Uncrossed.” If the SNr neuron was located in the hemisphere opposite the recorded SC neuron, the SNr neuron type is indicated in the column labeled “Crossed.” If the SNr neuron was located in the same hemisphere as the recorded SC neuron, the type is indicated in the column labeled “Uncrossed.” A total of 20 SNr stimulation sites and 20 SC neurons were from opposite sides of the brain (crossed). In all, 22 SNr sites and SC neurons were stimulated and recorded from the same side of the brain (uncrossed). The SC neuron types are indicated and included in the columns labeled “Crossed” and “Uncrossed” according to the same criteria as for SNr neuron types. The same RFs indicate that the approximate centers of the SNr and SC neurons were located in the same hemifield. Nonoverlapping RFs indicate that the centers did not overlap. Most were located in the opposite hemifield.