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Constanze Schmitt, Milosz Krala, Frank Bremmer; The neural basis of actively controlled visually simulated self-motion. Journal of Vision 2018;18(10):42. doi: 10.1167/18.10.42.
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Navigating through an environment requires knowledge not only about one's direction of self-motion (heading), but also about traveled distance. Previous behavioral studies have shown that human observers are able to actively reproduce a previously observed travel distance purely based on visual information. Here, we employed EEG to determine the neural substrate of actively controlled simulated self-motion as well as of distance reproduction. We measured event-related potentials (ERPs) during visually simulated straight forward self-motion across a ground plane. The stimulus was presented on a computer monitor 68 cm in front of the human observers, subtending the central 37° * 11° degrees of the visual field. The participants' task was to reproduce (active condition) a previously seen self-displacement (passive condition). Subjects had full control over travel speed, using a gamepad. We recorded the trajectories of self-motion during the active condition and played it back to the subjects in another set of trials (replay condition). A motor control condition was included to control for purely action-related ERPs. EEG-data were aligned to the onset or to the offset of the simulated self-motion. Additionally, if participants' actively traveled distance was longer than the remembered (control) distance, we aligned behavioral and EEG data also to the time point ToCD (Time of Control Distance) when the control distance had been passed. Evoked ERPs revealed higher amplitudes in the passive as compared to the active condition. This result is in line with the idea of attenuated responses to self-induced vs. externally-induced sensory stimulation. Wavelet based temporal-frequency analyses revealed activation in the theta-band in the active condition about 600 ms – 300 ms before the end of the movement. Interestingly, this time window coincides with the ToCD. This theta-band activation could be indicative of a neural comparator for action-related predictions and sensory outcomes.
Meeting abstract presented at VSS 2018
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