ORCID Profile
0000-0003-1597-7407
Current Organisation
University of Marburg
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Publisher: Elsevier BV
Date: 02-2012
Publisher: Elsevier BV
Date: 05-2021
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 12-2009
DOI: 10.1167/9.13.1
Publisher: Cold Spring Harbor Laboratory
Date: 08-02-2022
DOI: 10.1101/2022.02.05.479227
Abstract: Temporal information is ubiquitous in natural vision and must be represented accurately in the brain to allow us to interact with a constantly changing world. Recent studies have employed a random stimulation paradigm to map the temporal response function (TRF) to luminance changes in the human EEG. This approach has revealed that the visual system, when presented with broadband visual input, actively selects distinct temporal frequencies, and retains their phase-information for prolonged periods of time. This non-linear response likely originates in primary visual cortex (V1), yet, so far it has not been investigated on a neural level. Here, we characterize the steady-state response to random broadband visual flicker in marmoset V1. In two experiments, we recorded from i) marmosets passively stimulated under general anesthesia, and ii) awake marmosets, under free viewing conditions. Our results show that LFP coupling to the stimulus was broadband and unselective under anesthesia, whereas in awake animals, it was restricted to two distinct frequency components, in the alpha and beta range. Within these frequency bands, coupling adhered to the receptive field (RF) boundaries of the local populations. The responses outside the RF did not provide evidence for a propagation of stimulus information across the cortex, contrary to results in human EEG studies. This result may be explained by short fixation durations, warranting further investigation. In summary, our findings show that during awake behavior V1 neural responses to broadband information are selective for distinct frequency bands, and that this selectivity is likely controlled actively by top-down mechanisms.
Publisher: Springer Science and Business Media LLC
Date: 04-2020
DOI: 10.1007/S00221-020-05782-2
Abstract: Vision plays a central role in maintaining balance. When humans perceive their body as moving, they trigger counter movements. This results in body sway, which has typically been investigated by measuring the body’s center of pressure (COP). Here, we aimed to induce visually evoked postural responses (VEPR) by simulating self-motion in virtual reality (VR) using a sinusoidally oscillating “moving room” paradigm. Ten healthy subjects participated in the experiment. Stimulation consisted of a 3D-cloud of random dots, presented through a VR headset, which oscillated sinusoidally in the anterior–posterior direction at different frequencies. We used a force platform to measure subjects’ COP over time and quantified the resulting trajectory by wavelet analyses including inter-trial phase coherence (ITPC). Subjects exhibited significant coupling of their COP to the respective stimulus. Even when spectral analysis of postural sway showed only small responses in the expected frequency bands (power), ITPC revealed an almost constant strength of coupling to the stimulus within but also across subjects and presented frequencies. Remarkably, ITPC even revealed a strong phase coupling to stimulation at 1.5 Hz, which exceeds the frequency range that has generally been attributed to the coupling of human postural sway to an oscillatory visual scenery. These findings suggest phase-locking to be an essential feature of visuomotor control.
Publisher: Frontiers Media SA
Date: 24-02-2016
Publisher: Society for Neuroscience
Date: 24-07-2013
No related grants have been discovered for Frank Bremmer.