Eline Kupers is a Postdoctoral Research Fellow working with Professor Kalanit Grill-Spector in the Psychology Department. Her research focuses on how visual information is processed in space and time in the human brain. She uses psychophysics, eye tracking, and neuroimaging techniques (MRI, EEG/MEG) in combination with computational modeling to answer her research questions.
Eline received her PhD from New York University, working with Professor Jonathan Winawer and Professor Marisa Carrasco. During her graduate studies, she worked on models of the human visual system that describe the first steps in seeing (from the retina to primary visual cortex). In her postdoctoral work, she continues to work on computational models of vision, but focuses on the neural mechanisms involved in high-level vision.
Doctor of Philosophy, New York University (2020)
Master of Philosophy, New York University (2020)
Master of Arts, New York University (2018)
Master of Science, Universiteit Van Amsterdam (2015)
Bachelor of Science, Utrecht University (2012)
Modeling visual performance differences "around' the visual field: A computational observer approach
PLOS COMPUTATIONAL BIOLOGY
2019; 15 (5): e1007063
Visual performance depends on polar angle, even when eccentricity is held constant; on many psychophysical tasks observers perform best when stimuli are presented on the horizontal meridian, worst on the upper vertical, and intermediate on the lower vertical meridian. This variation in performance 'around' the visual field can be as pronounced as that of doubling the stimulus eccentricity. The causes of these asymmetries in performance are largely unknown. Some factors in the eye, e.g. cone density, are positively correlated with the reported variations in visual performance with polar angle. However, the question remains whether these correlations can quantitatively explain the perceptual differences observed 'around' the visual field. To investigate the extent to which the earliest stages of vision-optical quality and cone density-contribute to performance differences with polar angle, we created a computational observer model. The model uses the open-source software package ISETBIO to simulate an orientation discrimination task for which visual performance differs with polar angle. The model starts from the photons emitted by a display, which pass through simulated human optics with fixational eye movements, followed by cone isomerizations in the retina. Finally, we classify stimulus orientation using a support vector machine to learn a linear classifier on the photon absorptions. To account for the 30% increase in contrast thresholds for upper vertical compared to horizontal meridian, as observed psychophysically on the same task, our computational observer model would require either an increase of ~7 diopters of defocus or a reduction of 500% in cone density. These values far exceed the actual variations as a function of polar angle observed in human eyes. Therefore, we conclude that these factors in the eye only account for a small fraction of differences in visual performance with polar angle. Substantial additional asymmetries must arise in later retinal and/or cortical processing.
View details for DOI 10.1371/journal.pcbi.1007063
View details for Web of Science ID 000471040500063
View details for PubMedID 31125331
View details for PubMedCentralID PMC6553792
A non-invasive, quantitative study of broadband spectral responses in human visual cortex
2018; 13 (3): e0193107
Currently, non-invasive methods for studying the human brain do not routinely and reliably measure spike-rate-dependent signals, independent of responses such as hemodynamic coupling (fMRI) and subthreshold neuronal synchrony (oscillations and event-related potentials). In contrast, invasive methods-microelectrode recordings and electrocorticography (ECoG)-have recently measured broadband power elevation in field potentials (~50-200 Hz) as a proxy for locally averaged spike rates. Here, we sought to detect and quantify stimulus-related broadband responses using magnetoencephalography (MEG). Extracranial measurements like MEG and EEG have multiple global noise sources and relatively low signal-to-noise ratios; moreover high frequency artifacts from eye movements can be confounded with stimulus design and mistaken for signals originating from brain activity. For these reasons, we developed an automated denoising technique that helps reveal the broadband signal of interest. Subjects viewed 12-Hz contrast-reversing patterns in the left, right, or bilateral visual field. Sensor time series were separated into evoked (12-Hz amplitude) and broadband components (60-150 Hz). In all subjects, denoised broadband responses were reliably measured in sensors over occipital cortex, even in trials without microsaccades. The broadband pattern was stimulus-dependent, with greater power contralateral to the stimulus. Because we obtain reliable broadband estimates with short experiments (~20 minutes), and with sufficient signal-to-noise to distinguish responses to different stimuli, we conclude that MEG broadband signals, denoised with our method, offer a practical, non-invasive means for characterizing spike-rate-dependent neural activity for addressing scientific questions about human brain function.
View details for DOI 10.1371/journal.pone.0193107
View details for Web of Science ID 000427189300014
View details for PubMedID 29529085
View details for PubMedCentralID PMC5846788