Steven Scholte and I are now accepting applications for a new PhD position funded by the UvA's Data Science Center's Interdisciplinary PhD Programme! You can find details on the position and how to apply on the UvA's vacancy website and on academic transfer. Feel free to email me with inquiries on the position. Looking forward to hearing from you!
New paper in TICS
This new review paper in Trends in Cognitive Sciences is the result of a really fun collaboration with Tomas Knapen (VU), Tessa Dekker (UCL) and Edward Silson (U Edinburgh)! We review evidence for visuospatial coding throughout the brain and discuss the role that visuospatial coding plays in higher-order perception, cognitive development and action-perception integration. We propose that visuospatial coding (our window onto the world) is not thrown away by the brain but rather is retained to facilitate the exchange of visual information with other functional systems to the benefit of cognition.
Data Science grant
Pleased to announce that together with Steven Scholte from the Dept. of Psychology, I was awarded a grant from the UvA's Data Science Center (DSC) to hire a PhD student to work on integrating precortical processing models of vision with deep learning. The recruitement ad will be posted soon!
New preprint online
In this ECoG study done in collaboration with New York University and University Medical Center Utrecht, we measured and modeled temporal dynamics of visual responses at millisecond resolution in human cortex. We show that a simple computational model predicts a wide variety of complex neural response shapes that we induced experimentally by manipulating the duration, repetition and contrast of visual stimuli. By comparing data and model predictions, we uncover systematic properties of temporal dynamics of neural signals, allowing us to better understand how the human brain processes dynamic sensory information.
Two posters at ECVP 2021
Amber and Clemens will be attending ECVP 2021 and presenting work from their PhDs for the first time! Check out the program here: Amber will presenting "Adaptation of neural responses to naturalistic visual categories in low- and high-level visual cortex" on Monday Aug 23rd, 11:00am CEST and Clemens will be presenting "Human Perception of Navigational Affordances in Real-world Scenes" on Wednesday Aug 25th, 11:00 am CEST.
New preprint online
In this fMRI study, we performed a direct comparison of the relative visual field position of stimuli (contra- vs ipsilateral) and category (face or scene) to determine which of these two drives fMRI responses more strongly throughout visual cortex. Our results suggest that ventral-temporal visual regions are less position-sensitive than lateral-occipital regions, and that the 'transition' between category vs. position-dominance does not map cleanly onto known boundaries of retinotopic or category-selective cortex.
TMS-fMRI study published
Our study on the effect of theta-burst TMS on fMRI responses in category-selective brain regions in visual cortex is now out in NeuroImage! See this twitter thread for a short summary of the findings plus some extra information on our publication process for this paper, for which the data were collected during my first post-doc at NIH.
Neuromatch talk online
The talk I gave last month at Neuromatch 3.0 on the temporal dynamics of ECoG responses in visual cortex was recorded and can be freely watched online! It can be found here on Neuromatch's YouTube channel starting at 1.32.05 hrs in. The talk is about 12 minutes + a few minutes of questions. A cut-out recording of each talk separately should be made available soon!
New preprint: TMS-fMRI in lateral occipital cortex
Happy to share this preprint on a labor intensive experiment (4 fMRI sessions per subject!). Our findings suggest that the effect of TMS on fMRI responses to visual stimuli is not as specific as we might have expected from behavioral TMS findings, raising questions about the separability of cortical visual information processing networks with theta-burst fMRI.
New ECoG paper in Brain Topography
In collaboration with colleagues from Utrecht University and Lausanne we found evidence that neural responses to visual and tactile stimuli co-localize in visual cortex. I contributed only a small part (to the computational modeling of the visual responses), but the results provide an interesting case study of how sensory information processing can be input modality independent. Plus it's my first contribution to an ECoG paper!
New paper on scene complexity and decision-making
I co-authored a paper by Noor Seijdel and colleagues at the University of Amsterdam on the influence of scene statistics on perception. We found that image complexity as reflected in image statistics affects model parameters such as drift rate (rate of evidence accumulation) and boundary in drift diffusion decision-making models fitted to reaction time data when human observers perform a rapid object categorization task. The image statistics themselves were task-irrelevant, but they still had a strong influence on behavior. This suggests that in naturalistic settings (i.e. when viewing real-world images), very basic, low-level properties of our natural visual environment influence perceptual decision-making!
V-VSS 2020 presentation video
I am pleased to announce that next year I will be starting as an assistant-professor at the Faculty of Science of the University of Amsterdam sponsored by a MacGillavry Fellowship! I'm very excited about entering a new phase and starting my own research group in 2020.
Veni grant from NWO
NeuroImage paper out
In this paper, we tested how well human groupings of naturalistic images was reflected in patterns of fMRI activity in visual cortex. Contrary to what is commonly assumed, there was not a clear-cut mapping of the brain responses in ventral-temporal cortex to behavior, and comparisons with deep network models suggested that activity in these regions reflected lower level processing than what guided behavior. This suggests there's still a lot we don't understand about the representations in higher-order visual regions, especially not for naturalistic images! Note that the stimuli and data are freely available so others can test more models of visual representation against these behavioral and fMRI data!
NYU FAS Travel Award
I received the NYU Faculty of Arts and Sciences Postdoctoral Travel Award to sponsor my attendance at OHBM this year! I will be presenting our ECoG and fMRI work on temporal dynamics in visual cortex, in both a poster and a (selected) talk session.
Talk in Japan
On February 21st 2019, I will be giving an invited talk at the 5th CiNet Conference themed ‘Computation and Representation in Brains and Machines’, Center for Information and Neural Networks (CiNet) in Osaka, Japan.
I'm very excited to be among this line-up of esteemed speakers! It promises to be a very interesting meeting.
New paper in PLoS Comp Biol
It took a while, but I finally published the last chapter of my PhD thesis! The wonderful Sara Jahfari and I led this project together, looking at the influence of scene complexity (as determined by low-level image statistics) on detection of animal in natural scenes. It turns out that scene complexity affects the degree of evidence accumulation (as formalized in a drift diffusion) which for highly complex scenes appears to be driven by feedback activity.
New paper in eLife!
In this paper, we tested how well scene categorization behavior and patterns of fMRI activity in scene-selective cortex could be explained by three different models of scene information, quantifying the unique contributions of each. We found that the relative contributions of each model differ depending on whether you're looking at behavior or the brain - suggesting we have more work to do in terms of developing computational models that can explain both behavior and neural responses in the human brain.