Voluntary saccades performed in total darkness provide the opportunity to investigate the brain system active during saccades without confounding effects caused by the saccade induced shifts of the retinal image. Using this approach saccade related activation has been demonstrated not only in parietal but also in striate cortex. Currently no information is available about the reference frame in which this activation is represented in parietal and in striate cortex. However, knowledge about how the brain codes spatial information about saccades in the absence of visual input is potentially relevant to our understanding of visually guided behaviour. The present study combines functional magnetic resonance imaging (fMRI) with simultaneous electrooculogram-recordings to provide evidence that volitional saccades executed in total darkness are represented in a retinotopic reference frame in a parietal brain area, the putative homologue of human LIP, and in a head/body centred egocentric reference frame in human V1. The potential co-existence of retinotopic and egocentric space representations in the primary visual cortex indicates that V1 may be involved in visuo-motor integration.
- Egocentric reference frame
- Functional magnetic resonance imaging
- Parietal cortex
- Retinotopic reference frame
- Striate cortex
- blood oxygenation level dependent
- functional magnetic resonance imaging