The Kolk lab
Developmental Neurobiology

Dr. Sharon Kolk

Associate Professor of Developmental Neurobiology

After my graduation in the field of Neuroendocrinology at the University of Utrecht I started my PhD at the Radboud University Nijmegen. After graduation, I went to the US to do a postdoc at the Yale University Medical School, followed by a postdoc position at the Rudolf Magnus Brain Institute in Utrecht. In 2009, I started my lab at the Radboud University Nijmegen focusing on the molecular and cellular underpinnings of developing brain areas. Currently PI of several large collaboration grants such as the NWA-ORC ProMiSe, ITN Serotonin&BEYOND and BRAINCHAIN.

 Dr. Jasper Visser, MD

Neurologist and visiting researcher

I am a neurologist, specialized in movement disorders, and a medical biologist. I graduated in Biology and Medicine at Utrecht University and trained as a neurologist at RadboudUMC. At the same time, I did a PhD at Radboud university focusing on the role of certain brain regions (the 'basal ganglia') in the control of posture and balance. Later I joined the Kolk lab as a researcher studying brain development, particularly of dopamine neurons and their role in Lesch-Nyhan disease — a metabolic disorder with unique neurobehavioral features — in order to contribute to future treatment strategies. Bridging clinical neurology and neuroscience is a major objective in my work.

Jet Coenen-van der Spek, MD, MSc

PhD candidate

I obtained my bachelor's degree at University College Utrecht (Utrecht University, the Netherlands), where I followed the pre-medical track. Then I was accepted into the Selective Utrecht Medical Master (SUMMA) program, training me to become a medical doctor and a researcher. I moved to the Radboud University Medical Center to work as a resident (ANIOS) in Clinical Genetics, seeing patients with general genetic problems, including neurodevelopmental disorders. I became really interested in this patient group, which is why I joined the Kolk Lab for a PhD from October 2020. Here I study monogenetic neurodevelopmental disorders using several approaches, varying from clinical to organoid studies.

 Sara Sebastiani, MSc

PhD candidate

I graduated in the bachelor's course of Medical Biotechnology at the University of Milan and I have a master's degree in Medical Biotechnology and molecular medicine – curriculum Neuroscience (Faculty of Medicine, University of Milan). 

Later, I joined the Kolk Lab in October 2020, as a PhD candidate. Within the ProMiSe project, I study the pathogenic mechanism of neurodevelopmental disorders in which the prefrontal cortex is affected, by means of cortical brain organoids and animal models.


Marta Samina, MSc

PhD candidate

I received my bachelor's degree in Molecular and Cellular Biology at the Faculty of Science and Technology, New University of Lisbon. Later, in 2020, I obtained a master's degree in Neurobiology at the Faculty of Medicine, University of Porto. Back in September 2021, I joined the Kolk Lab as ESR7 for Serotonin&BEYOND. In my PhD project, I aim to causally delineate how lifelong increases and decreases in serotonin levels affect PFC microstructure, behavior, and cognition.

Jurjan Havelaar, MSc

PhD candidate

I graduated from the University of Wageningen with a bachelor's degree in Biology - specialization in human and animal health biology. After my bachelor's, I moved to Nijmegen where I obtained a master's degree in Medical Biology at the Radboud University. I first joined the Kolk lab during my master's as an intern and then as a PhD in 2021. My PhD project aims to investigate the molecular mechanisms underlying the neurodevelopmental disorder Lesch-Nyhan disease, with a special focus on the timing of pathogenic events.

Willemijn Claassen, MSc

PhD candidate

I obtained my bachelor's degree in Applied Science at the Fontys in Eindhoven and graduated from Radboud University with a pre-master and master Medical Biology in 2021. After my studies, I started working as a research assistant at the Max Planck Institute for Psycholinguistics where I supported researchers in differentiating iPSCs into cerebral organoids. I joined the Kolk lab in February 2024 as a PhD student within the ProMiSe consortium and will be working on studying the molecular mechanisms of different neurodevelopmental disorders by means of cerebral organoids.

Juliette Monquil, MSc 

Assistant teacher and research assistant

I obtained my bachelor's degree in Biology and master's in Medical Biology, with a specialization in (molecular) Developmental Biology, from Radboud University, Nijmegen. I joined the Kolk lab in October 2021 as an assistant teacher in Developmental (Neuro)Biology, additionally working as a coordinator for the ProMiSe ​​project. I am primarily involved in our bachelor courses - Medical Embryology and Neurodevelopment.

Daan Roelofs, BSc

Student assistant

I just obtained my bachelor's degree in Molecular Life Sciences at Radboud University. I am currently enrolled in the Neurobiology's master and helping the different research projects in the Kolk group.