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Published on: August 7, 2017
Functional connectivity in vergence and saccade eye movement tasks assessed using Granger Causality analysis
Yelda Alkan1, Tara L Alvarez, Suril Gohel
1Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA.
Summary
This study used Granger Causality Analysis (GCA) to map brain connections during eye movements. Predictive tasks and vergence movements showed more neural interactions than simple tracking.
Area of Science:
- Neuroscience
- Cognitive Science
- Ophthalmology
Background:
- Human visual system uses saccade and vergence eye movements for information acquisition.
- Functional MRI (fMRI) reveals activated brain regions but not their interactions.
- Granger Causality Analysis (GCA) quantifies directional influences between neural regions.
Purpose of the Study:
- To investigate the number and direction of neural influences among regions of interest (ROIs) during saccade and vergence eye movements.
- To compare neural interactions during simple visual tracking versus cognitively demanding predictive tasks.
Main Methods:
- Employed GCA to analyze fMRI data from eight subjects across four experiments.
- Utilized two stimulus protocols: fixation vs. random movements, and random vs. predictable movements.
- Tested both saccadic and vergence eye movements under each protocol.
Main Results:
- Predictive tasks elicited significantly more connections between ROIs compared to simple tracking.
- The vergence prediction task showed more neural connections than the saccade prediction task.
- Increased cognitive demand and vergence movements correlated with greater ROI interconnectedness.
Conclusions:
- Neural network complexity increases with cognitive demand during eye movement tasks.
- Vergence eye movements may involve more extensive neural interactions than saccadic movements.
- GCA provides valuable insights into the dynamic interactions within the human visual system.
