Fig. 7
Double dissociation of SC microsaccade-related discharge for visually- and memory-guided microsaccades. a Movement RF’s of an example SC neuron. Left shows peri-movement discharge (like in Fig. 6b) for memory-guided microsaccades; right shows the same for corrective, visually-guided microsaccades. The neuron was silent for the visually-guided movements, but not for similar-sized memory-guided ones. b Peri-movement discharge of the same neuron under the two conditions. The black curve (when visible) shows the neuron’s activity during fixation before trial onset; the neuron only discharged for memory-guided, but not visually guided, microsaccades. Error bars denote 95% confidence intervals. c, d Same as a, b but for an example neuron only showing microsaccade-related discharge for visually guided movements (similar to visually dependent saccade-related, VDSR, neurons46). The inset shows (as an example) the analyzed eye movements (like Fig. 6a) in the two conditions, demonstrating clear overlap (similar overlap was present in a, b). e Distribution of the different neuron types (V = Visual; VM = Visual-motor; M = Motor; VDSR = Visually-dependent saccade-related; ER = Exclusively responding for memory-guided microsaccades). f Movement RF hotspots for the neurons. ER-Neurons tended to be more eccentric than other neurons exhibiting microsaccade-related discharge, consistent with a foveal expansion for memory-guided microsaccades (see text and Supplementary Fig. 5). g, h Peri-stimulus (g) or peri-microsaccadic (h) discharge for all of our encountered neuron types during microsaccade generation. Each neuron’s response was first normalized before averaging responses across neurons. V- and VM-Neurons exhibited strong visual responses; VM- and M-Neurons showed movement-related activity regardless of stimulus; VDSR-Neurons only showed movement-related activity in the presence of a visual target; ER-Neurons only showed movement-related activity in the absence of a visual target. In all cases, we analyzed neural activity for microsaccades (<1o) toward the RF. Error bars denote 95% confidence intervals
