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Updated: Jun 23, 2026
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Assessing Corticospinal Excitability During Goal-Directed Reaching Behavior
Published on: December 2, 2022
Brain activation during immediate and delayed reaching in optic ataxia
Marc Himmelbach1, Marion Nau, Ida Zündorf
1Hertie-Institute for Clinical Brain Research, Eberhard Karls University, Tübingen, Germany. marc.himmelbach@uni-tuebingen.de
Neuropsychologia
|May 12, 2009
Summary
Patients with optic ataxia show improved accuracy in delayed movements, suggesting the dorsal stream
Area of Science:
- Neuroscience
- Cognitive Psychology
- Neuroimaging
Background:
- Optic ataxia patients exhibit movement deviations to peripheral targets.
- Paradoxical accuracy improvement in delayed movements suggests non-dorsal stream involvement.
- Previous assumptions questioned the dorsal stream's role in localization for these patients.
Purpose of the Study:
- Investigate brain activity during immediate and delayed movements in an optic ataxia patient.
- Compare visuomotor network activation in patients and healthy controls.
- Test the hypothesis that residual visuospatial abilities rely on systems outside the dorsal stream.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used.
- Brain activity was recorded during immediate and delayed pointing tasks.
- Data from one optic ataxia patient (I.G.) and 16 healthy subjects were analyzed.
Main Results:
- Intact dorsal occipital and parietal areas showed similar activation for both movement types in the patient.
- Healthy subjects activated the same visuomotor network for immediate and delayed movements.
- Healthy subjects showed additional activation in occipito-parietal and occipito-temporal areas for visible targets.
Conclusions:
- Dorsal areas are involved in both immediate and delayed reaching in healthy individuals and the optic ataxia patient.
- The findings challenge the notion that optic ataxia patients' residual visuospatial skills are solely mediated by non-dorsal stream systems.
