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Visual cortex excitability increases during visual mental imagery--a TMS study in healthy human subjects
Roland Sparing1, Felix M Mottaghy, Giorgio Ganis
1Laboratory for Magnetic Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02214, USA.
Brain Research
|May 29, 2002
Summary
Visual mental imagery enhances visual cortex excitability, as shown by a reduced phosphene threshold. This task-dependent modulation indicates early visual areas actively participate in visual imagery.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Visual Perception
Background:
- Neuroimaging studies suggest primary visual cortex involvement in visual mental imagery.
- Motor imagery is known to increase motor cortex excitability.
Purpose of the Study:
- To investigate if visual imagery similarly increases visual cortex excitability.
- To test the hypothesis that visual imagery decreases the phosphene threshold (PT).
Main Methods:
- Transcranial magnetic stimulation (TMS) was used to elicit phosphenes in the primary visual cortex.
- The phosphene threshold (PT) was determined by applying TMS with increasing intensity.
- Participants performed a visual imagery task and an auditory control task.
Main Results:
- Visual imagery task significantly decreased the phosphene threshold (PT) compared to baseline.
- The auditory control task did not alter the PT.
- This modulation of PT was observed regardless of the location of the visual image.
Conclusions:
- Visual mental imagery causes a short-term, task-dependent modulation of visual cortex excitability.
- These findings provide evidence for the participation of early visual areas in visual imagery processing.
Keywords:
Non-programmatic