Saccadic eye movements evoked by microstimulation of striate cortex

• Published in: The European journal of neuroscience 2003-02, Vol.17 (4), p.870-878
• Main Authors: Tehovnik, Edward J., Slocum, Warren M., Schiller, Peter H.
• Format: Article
• Language: English
• Subjects: Animals; Behavior, Animal; Chronaxy - radiation effects; current thresholds; Dose-Response Relationship, Radiation; Electric Stimulation - methods; electrical stimulation; Electrodes; eye movements; Fixation, Ocular - radiation effects; Macaca mulatta; occipital cortex; phosphenes; Probability; Reaction Time - radiation effects; Reinforcement (Psychology); rhesus monkeys; Saccades - physiology; Saccades - radiation effects; Sensory Thresholds - radiation effects; Visual Cortex - anatomy & histology; Visual Cortex - physiology; Visual Cortex - radiation effects; Visual Fields
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1046/j.1460-9568.2003.02489.x

Experiments were performed to assess the excitability of neural elements activated while inducing saccadic eye movements electrically from different cortical layers of striate cortex (area V1) in rhesus monkeys. Excitability was assessed by measuring current thresholds, saccadic latencies, chronaxies, and the effectiveness of anode‐first vs. cathode‐first pulses. Minimum current thresholds for the evocation of saccades (i.e. less than 5 µA) were observed when the deepest layers of V1 were stimulated. The shortest saccadic latencies were also observed at these depths. The shortest latency at 10 times the threshold current was 49 ms on average. The chronaxies of the elements mediating saccades were less in deep V1 (i.e. 0.17 ms) than in superficial V1 (i.e. 0.23 ms). Anode‐first pulses were more effective at evoking saccades from superficial V1, whereas cathode‐first pulses were more effective at evoking saccades from deep V1. These results indicate that the excitability properties of superficial and deep V1 are distinct for the generation of saccades. Moreover, the excitability of elements mediating saccades in V1 of monkeys is comparable to that of elements mediating phosphenes in human V1.