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17 november 2017

Understanding how the brain orchestrates our thoughts and actions and how it is affected in disease are arguably among the most complex questions facing science today. Although classic biophysical work has firmly established how neuronal signals can emerge from the interplay between different types of (voltage-gated) ion channels, much less is known about the precise generation, propagation and integration of electrical signals within the highly branched and extended morphology of individual neurons embedded in intact neuronal systems. For example, how signals propagate reliably through neuronal branch points is unknown. In addition, how the nanoscale spatial organization of ion channels at the initiation site shapes action potentials (APs) and how signals can be spatially shaped by modulating inputs is poorly understood. This is largely due to the difficulty of obtaining dynamic information from neurons within intact brain circuits.
Although the past decade has seen a wave of breakthroughs in light-based imaging and stimulation techniques to probe neuronal organization and activity at high spatial and temporal resolution, these techniques suffer from dramatic optical distortions as one proceeds deeper inside the tissue. Currently, wavefront shaping methods are emerging that could correct for these tissue-induced aberrations and allow deeper imaging at improved resolution. Within the Programme Neurophotonics, experts in the field of single-neuron physiology (Kole, Wierenga) join forces with experts in advanced imaging and wavefront shaping technology (Mosk, Vellekoop, Gerritsen, Kapitein). The goal is to use advanced light-based methodology to unravel the physical principles underlying signal generation, propagation and integration in neurons embedded in functional circuits.
In this PhD project, digital holography will be used to detect mechanical and optical changes that accompany the propagation of the action potential through an axon in an intact 3D neuronal network. Different forms of wavefront-shaping will be employed to optimize contrast and reduce background signals.

Job description
In this PhD project, digital holography will be used to detect mechanical and optical changes that accompany the propagation of the action potential through an axon in an intact 3D neuronal network. Different forms of wavefront-shaping will be employed to optimize contrast and reduce background signals.
The key challenge in this project is the detection of 10-nm changes in diameter of a living neuron in a 3D tissue slice. Optical interferometry can typically detect much smaller signals in rigid media, and interferometric detection of these signals in neurons that lie flat on a glass plate has been accomplished. To achieve the same in 3D, wave-front shaping and digital optical phase conjugation methods will be developed to suppress background and filter out the signals due to the action potential.
You will learn to design and apply digital wavefront shaping optics as well as advanced signal processing methods to separate signal from background, first in model systems, and later in living neurons. You will also learn to handle and study living tissue samples, provided by our partners, using state of the art methods from biophysics including two-photon calcium microscopy.
You will report on your results at national and international meetings, through peer-reviewed publications, and in the form of a PhD thesis. You will benefit from the expertise of the Light in Complex Systems group (led by Allard Mosk) and the Biophysics group (led by Hans Gerritsen) of the Debye Institute for Nanomaterials Science. As a member of both groups you will have access to a wide range of laboratory infrastructure, instrumentation and technical support.

We are looking for a creative and open-minded physicist with a strong interest in physical optics and microscopy and biophysics. Experience with programming and data acquisition is considered advantageous.
Scientific curiosity, skill in design and integration of experiments and integration of analytic capabilities with a decisive approach will bring you toward success in this project.
In addition, because you will be part of a multidisciplinary consortium, good communication skills and a genuine interest in different branches of science are very important.

Conditions of employment
When fulfilling a PhD position at NWO-I, the Institutes Organisation of NWO, you will get the status of junior scientist. You will have an employee status and can participate in all the employee benefits NWO-I offers. You will get a contract for four years. Your salary will be up to a maximum of 2,834 euro gross per month. The salary is supplemented with a holiday allowance of 8 percent and an end-of-year bonus of 8.33 percent. You are supposed to have a thesis finished at the end of your four year term with NWO-I. A training programme is part of the agreement. You and your supervisor will make up a plan for the additional education and supervising that you specifically need. This plan also defines which teaching activities you will be responsible (up to a maximum of ten percent of your time). The conditions of employment of NWO-I are laid down in the Collective Labour Agreement for Research Centres (Cao-Onderzoekinstellingen), more exclusive information is available at this website under Personeelsinformatie (in Dutch) or under Personnel (in English). General information about working at NWO-I can be found in the English part of this website under Personnel. The 'Job interview code'applies to this position.

University of Utrecht.
This position is one of the five PhD positions of the Neurophotonics programme and will benefit from the interactions between local partners (Wierenga, Kapitein) and the other consortium members (Kole and Vellekoop).

Prof.dr. Allard P. Mosk.

Please upload a motivation letter, CV, a summary of your grades and the contact details of two references.
Important: do not upload scans of personal documents or certificates.

Closing time
 15 August 2017.




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