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Updated: Jul 15, 2026
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Using Saccadometry with Deep Brain Stimulation to Study Normal and Pathological Brain Function
Published on: July 14, 2016
Parietal stimulation destabilizes spatial updating across saccadic eye movements
Adam P Morris1, Christopher D Chambers, Jason B Mattingley
1Cognitive Neuroscience Laboratory, School of Behavioral Science, University of Melbourne, Melbourne, Victoria 3010, Australia. morrisa@unimelb.edu.au
Summary
Human intraparietal sulcus (IPS) plays a key role in spatial updating during saccadic eye movements. Stimulating the posterior IPS (IPSp) disrupted accurate second-saccade targeting, revealing its importance for visual stability.
Area of Science:
- Neuroscience
- Cognitive Science
- Human Vision
Background:
- Saccadic eye movements rapidly shift visual input, yet our perception of space remains stable.
- Neural mechanisms for transsaccadic spatial updating are well-studied in macaques but less understood in humans.
- The intraparietal sulcus (IPS) is implicated in spatial representation and sensorimotor integration.
Purpose of the Study:
- To investigate the role of human intraparietal areas in transsaccadic spatial updating.
- To determine if noninvasive cortical stimulation of the IPS can modulate spatial updating.
- To examine the temporal dynamics of spatial updating within the human IPS.
Main Methods:
- Used a double-step saccade task combined with noninvasive cortical stimulation (e.g., TMS) over human intraparietal areas.
- Stimulated the posterior termination of the intraparietal sulcus (IPSp) and an adjacent IPS site.
- Analyzed the endpoints of second saccades to assess the impact of stimulation on spatial updating.
Main Results:
- Stimulation over the right hemisphere IPSp broadened and shifted second-saccade endpoints when the initial saccade was contralateral.
- These endpoint shifts were persistent, suggesting enduring modulation of neural function (e.g., neuronal gain).
- The spatial representation in IPSp was updated immediately after the first saccade, while adjacent IPS stimulation had no effect.
Conclusions:
- The posterior intraparietal sulcus (IPSp) is critical for updating spatial representations following saccadic eye movements in humans.
- Stimulation of IPSp appears to distort eye position or displacement signals essential for transsaccadic updating.
- This sensory-motor integration in IPSp is vital for maintaining visual stability and guiding actions across saccades.
