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Microstimulation of macaque V1 disrupts target selection: effects of stimulation polarity
Edward J Tehovnik1, Warren M Slocum
1Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, E25-634, Cambridge, MA 02139, USA. tehovnik@mit.edu
Abstract:
Microstimulation of the intermediate layers of V1 in rhesus monkeys disrupts target selection with saccadic eye movements. To study target selection, one visual target was presented in the receptive-field location of the stimulated neurons and a second target was presented outside this location. Microstimulation delivered with the appearance of the two targets decreased the probability that the monkey would select the target placed in the receptive-field location when intermediate layers of V1 were stimulated. This interference effect was more pronounced when anodal-first pulse pairs were used as compared to when cathodal-first pulse pairs were used. The superior effectiveness of anodal pulses suggests that the interference effect is due to activation of axonal terminals residing within intermediate V1.
Insights
Researchers stimulated V1 brain layers in monkeys, disrupting visual target selection for eye movements. Anodal stimulation proved more effective, suggesting axonal terminal activation in V1 interferes with saccadic eye movements.
Area of Science:
- Neuroscience
- Ophthalmology
- Primate Studies
Background:
- The intermediate layers of the primary visual cortex (V1) are crucial for visual processing.
- Understanding how V1 activity influences visually guided behaviors like target selection is essential.
Purpose of the Study:
- To investigate the causal role of V1 intermediate layer microstimulation in disrupting target selection during saccadic eye movements.
- To determine the effect of different stimulation polarities (anodal vs. cathodal) on this disruption.
Main Methods:
- Microstimulation was applied to V1 intermediate layers in rhesus monkeys.
- Two visual targets were presented: one within the stimulated neurons' receptive field and one outside.
- Monkey's target selection behavior was recorded and analyzed.
Main Results:
- Microstimulation of V1 intermediate layers significantly decreased the probability of selecting the target within the receptive field.
- This interference effect was more pronounced with anodal-first pulse pairs compared to cathodal-first pulse pairs.
- The findings suggest that V1 intermediate layer stimulation activates axonal terminals, disrupting target selection.
Conclusions:
- Microstimulation of V1 intermediate layers causally disrupts target selection in saccadic eye movements.
- Anodal stimulation is more effective in causing this disruption, supporting the role of axonal terminal activation.
- These findings enhance our understanding of V1's role in sensorimotor control and decision-making.