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Spatio-temporal brain activation profiles associated with line bisection judgments and double simultaneous visual
R L Billingsley1, P G Simos, S Sarkari
1Division of Clinical Neurosciences, Department of Neurosurgery, Vivian L. Smith Center for Neurologic Research, University of Texas-Houston Medical School, 1333 Moursund Street, Suite H114, Houston, TX 77030, USA. rebecca.i.billingsley@uth.tmc.edu
Behavioural Brain Research
|May 12, 2004
Summary
Magnetic source imaging reveals right parietal cortex activity during visual perception tasks. Increased brain activity in right occipital and parietal areas may explain visual extinction.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Brain Imaging
Background:
- Line bisection and simultaneous visual stimulation are used to study spatial attention and visual perception.
- Previous studies implicated the right parietal cortex in these functions using lesion and hemodynamic methods.
Purpose of the Study:
- To investigate the spatio-temporal brain activity patterns during line bisection and double simultaneous visual stimulation using magnetic source imaging (MSI).
- To explore the neural basis of visual extinction and compare it with the hemispheric rivalry account.
Main Methods:
- Magnetic Source Imaging (MSI) was employed on 14 healthy adult participants.
- Participants performed line bisection judgments and responded to single and double simultaneous visual stimuli.
Main Results:
- The right inferior parietal cortex showed the highest concentration of activity sources, particularly between 200-300 ms post-stimulus onset.
- Bilateral stimulus presentation elicited more significant activity in the right inferior parietal, occipital, and prefrontal cortices compared to unilateral presentation.
Conclusions:
- The findings support the role of the right inferior parietal cortex in spatial attention and visual perception.
- A revised physiological explanation for visual extinction suggests increased neuronal excitation in right occipital and parietal cortices is necessary for accurate bilateral visual perception, rather than solely hemispheric rivalry.