Research

EWI - SACS

Current BSc or MSc project:

  • Marissa Frijns (MSc)
  • Abel Hanssen (MSc)
  • Niek Huttinga (MSc)
  • Normen Oude Booiink (MSc)
  • Manu Kalia (Msc) start Nov. 2016
  • Nick Luiken (MSc)
  • Wei Zong (MSc) start Jan. 2017 

You can find above mentionned students in the SACS MSc room: ZI-3070


Finished MSc projects

This list (under construction, by no means complete) is meant to give you an impression about what could be achieved during your final project period, and how a thesis in our area could look like.


Vacant Msc projects

  • Two projects on "Electrical Activity Mapping of the Subthalamic Nucleus: improvement of DBS protocols in Parkinson's Disease
Project 1.: Source reconstruction to optimize steering

Deep brain stimulation (DBS) for Parkinson's Disease is an effective treatment for many patients for whom medication is no longer sufficient. It consists of placing an electrode with a stereotactic procedure in the subthalamic nucleus (STN), a brain structure in the basal ganglia involved in motor control. Next, continuous high frequency current stimulation diminishes symptoms. The stimulation amplitude must be high enough to achieve a therapeutic effect but cannot be too high as that will cause unwanted side effects. Then the stimulation also affects other brain nuclei and fiber bundles leading to muscle contractions, sensory deficits but also mood changes.
Side effects may be diminished using directional steering of the applied electrical field. The aim is to target only the desired part of the STN and not on the surrounding nerve fibers. This claim has been proven in a recent study [1] where stimulation with steering induced side effects at higher stimulation amplitudes. During that study also local field potentials (LFP) were recorded [2]. The lead, i.e. electrode, has a new design with 32 contact points in a checkerboard pattern. The current electrode only has 4 simple circular contact points, and typically only two of them lie within the desired subregion of the STN. Hence these new high resolution LFP data enable two new explorative studies.

The STN is the preferred target for DBS, but its size is small comparable to a peanut. Despite careful planning the electrode might be placed suboptimally within the STN. As a result, the stimulation amplitude required for a therapeutic effect may be out of reach as the electrical field could activate neural tissue outside the STN or the wrong, non-sensomotoric part of the STN [3]. In this case, the use of steering is very attractive as it enables a much more specific modulation of STN electrical activity.

It is not so clear, however, which directional mode would be optimal for stimulation. A manual optimization of the 32 contact points is clearly unfeasible. LFP measurements through the same contact points as with which stimulation is performed, could reveal which part of the STN displays pathological beta activity. This requires inverse modelling where the source should be required to lie within the STN. In addition, multiple sources may be found. The results of this project will allow to optimize which electrodes to use for stimulation. In this way the LFP recordings can be used as an automatic feedback for the stimulation parameters and no extensive clinical testing to optimize the stimulation parameters is necessary.


Literature:
Directional steering: A novel approach to deep brain stimulation.
Contarino, M.F., Bour, L.J., Verhagen, R., Lourens, M.A.J., de Bie, R.M.A., van den Munckhof, P. and P.R. Schuurman, Neurology (2014) vol. 83(13): 1163-1169Directional Recording of Subthalamic Spectral Power Densities in Parkinson's Disease and the Effect of Steering Deep Brain Stimulation.
Bour, L.J., Lourens, M.A.J., Verhagen, R., de Bie, R.M., van den Munckhof, P., Schuurman, P.R. and Contarino, M.F., Brain Stimulation (2015) vol. 8(4):730-741.Functional neuronal activity and connectivity within the subthalamic nucleus in Parkinson's disease.
Lourens, M.A.J., Meijer, H.G.E., Contarino, M.F., van den Munckhof, P., Schuurman, P.R., van Gils, S.A. and Bour, L.J., Clin Neurophysiol (2013) vol. 124(5):967-981Coordinated reset stimulation in a large-scale model of the STN-GPe circuit. 
Ebert, M., Hauptmann, C. and Tass, P.A., Front Comput Neurosci (2014) 8:154Long-term electrical inhibition of deep brain targets in movement disorders. 
Benabid A.L., Benazzouz, A., Hoffmann, D., Limousin, P., Krack, P. and Pollak, P., Mov Disord (1998) Vol. 13 Suppl 3: 119-125Subthalamic nucleus phase-amplitude coupling correlates with motor impairment in Parkinson's disease, 
van Wijk, B.C., Beudel, M., Jha, A., Oswal, A., Foltynie, T., Hariz, M.I., Limousin, P., Zrinzo, L., Aziz, T.Z., Green, A.L., Brown, P. and Litvak, V., Clin Neurophysiol (2016) vol. 127(4): 2010-2019

WHEN INTERESTED PLEASE CONTACT:  DR. H.G.E. MEIJER

Project 2.: Analysis of phase-amplitude coupling in the STN for coordinated-reset stimulation

Deep brain stimulation (DBS) for Parkinson's Disease is an effective treatment for many patients for whom medication is no longer sufficient. It consists of placing an electrode with a stereotactic procedure in the subthalamic nucleus (STN), a brain structure in the basal ganglia involved in motor control. Next, continuous high frequency current stimulation diminishes symptoms. The stimulation amplitude must be high enough to achieve a therapeutic effect but cannot be too high as that will cause unwanted side effects. Then the stimulation also affects other brain nuclei and fiber bundles leading to muscle contractions, sensory deficits but also mood changes.
Side effects may be diminished using directional steering of the applied electrical field. The aim is to target only the desired part of the STN and not on the surrounding nerve fibers. This claim has been proven in a recent study [1] where stimulation with steering induced side effects at higher stimulation amplitudes. During that study also local field potentials (LFP) were recorded [2]. The lead, i.e. electrode, has a new design with 32 contact points in a checkerboard pattern. The current electrode only has 4 simple circular contact points, and typically only two of them lie within the desired subregion of the STN. Hence these new high resolution LFP data enable two new explorative studies.

Coordinated reset (CR) has been proposed as a more efficient stimulation protocol for deep brain stimulation [4] as opposed to continuous stimulation, which is being used conventionally [5]. This novel stimulation protocol consists of stimulation with a cycling pattern of brief high-frequency pulse trains at multiple electrode contacts. This type of stimulation is done to consecutively reset the phases of the different stimulated neuronal subpopulations. This is hypothesized to divide the neuronal population into phase-shifted subpopulations, causing an unlearning of both pathological neuronal synchrony and pathological synaptic connectivity. This means that once the connectivity has been changed, in contrast to the conventional stimulation, the high frequency stimulation temporarily can be turned off. If the mean frequency of stimulation, pulse amplitude can be reduced with CR stimulation, less energy is needed, and batteries can be replaced or recharged after longer intervals. Moreover, smaller stimulators can be developed. Most importantly, a reduced stimulation current could result in less side effects. Such improvements can result in a further improved quality of life for patients undergoing DBS. Hypothetically the CR protocol by plastic changes would affect the pathological neural circuits and reset them in a persistent way.

To apply CR stimulation optimally the new LFP data will allow to investigate the synchronization within the STN in a much higher spatial and temporal resolution. In particular it could reveal whether the synchronization in the STN is homogeneous, or that there are substructures with a particular phase difference in their activity. This can be revealed through a Phase-Amplitude Coupling (PAC) analysis [6]. This kind of analysis may reveal substructures within the STN and thismay aid in the design of CR-protocols. Also our understanding of the spatial distribution of neural activity at particular frequencies in STN will be increased.

Literature:
Directional steering: A novel approach to deep brain stimulation.
Contarino, M.F., Bour, L.J., Verhagen, R., Lourens, M.A.J., de Bie, R.M.A., van den Munckhof, P. and P.R. Schuurman, Neurology (2014) vol. 83(13): 1163-1169Directional Recording of Subthalamic Spectral Power Densities in Parkinson's Disease and the Effect of Steering Deep Brain Stimulation.
Bour, L.J., Lourens, M.A.J., Verhagen, R., de Bie, R.M., van den Munckhof, P., Schuurman, P.R. and Contarino, M.F., Brain Stimulation (2015) vol. 8(4):730-741.Functional neuronal activity and connectivity within the subthalamic nucleus in Parkinson's disease.
Lourens, M.A.J., Meijer, H.G.E., Contarino, M.F., van den Munckhof, P., Schuurman, P.R., van Gils, S.A. and Bour, L.J., Clin Neurophysiol (2013) vol. 124(5):967-981Coordinated reset stimulation in a large-scale model of the STN-GPe circuit. 
Ebert, M., Hauptmann, C. and Tass, P.A., Front Comput Neurosci (2014) 8:154Long-term electrical inhibition of deep brain targets in movement disorders. 
Benabid A.L., Benazzouz, A., Hoffmann, D., Limousin, P., Krack, P. and Pollak, P., Mov Disord (1998) Vol. 13 Suppl 3: 119-125Subthalamic nucleus phase-amplitude coupling correlates with motor impairment in Parkinson's disease, 
van Wijk, B.C., Beudel, M., Jha, A., Oswal, A., Foltynie, T., Hariz, M.I., Limousin, P., Zrinzo, L., Aziz, T.Z., Green, A.L., Brown, P. and Litvak, V., Clin Neurophysiol (2016) vol. 127(4): 2010-2019

WHEN INTERESTED PLEASE CONTACT:  DR. H.G.E. MEIJER

  • E-Nose
Development of an electronic nose wavelet for medical diagnostics

Supervisors: Bernard Geurts (University of Twente),

Jan Willem Gerritsen (The eNose Company, Zutphen)

Since ancient times, it has been known that smell contains information on a person’s physical condition. A possible source of smell is the exhaled breath, containing large numbers of different volatile substances. Detecting specific volatiles, e.g., using an electronic nose (eNose), would make it possible to distinguish between sick and healthy individuals. Such technology enables new, non-invasive diagnostic opportunities, easing patients’ lives, and supporting physicians in their diagnostic decisions. Finally, the eNose has the potential to contribute to decreasing the financial burden of healthcare for the community. The eNose Company (located in Zutphen) is capable of manufacturing electronic noses for dedicated high-volume applications. Composed of standard electronic components, small and robust devices can be produced at low costs. Calibration models for specific diseases can be developed and subsequently transferred to an unlimited number of electronic noses. For the first time, this enables high-volume application of electronic noses. A dedicated eNose has been developed in recent years for exhaled-breath analysis: the Aeonose. The patient should breathe gently into this battery-powered instrument for a couple of minutes. The data obtained are analysed using embedded software as well as computing power available remotely. This can give a screening result within minutes, after which further medical steps can be initiated if the results so indicate. After replacing the mouth piece and carbon filters, the device is ready for the next measurement. A major component for the robust and reliable operation of an eNose is the analysis and interpretation of the data that are collected. Currently, data analysis is being performed using standard data compression and classification techniques. In order to achieve higher sensitivity and specificity for the device, we aim at developing a wavelet, dedicated for the signal structures of the Aeonose. For this purpose, knowledge on the excitation and chemo/ physical properties of the sensors will be incorporated to arrive at new compression methods tailored for the specific device and disease-specific volatiles. Specific steps are:·

  • Literature study on (a) thermo-physical properties of the Aeonose-sensors and gas mixtures and on (b) wavelet transform
  • Creating specific wavelet transforms for the eNose based on a mathematical model and analysis of the main processes on which it relies
  • Comparing results obtained with the new wavelet and existing techniques. A software module for comparing different approaches is available.
  • Optimization of the preferred wavelet transform and testing it on a number of diseases
  • Writing a report documenting the findings, developments, and recommendations

To apply for this position, please send your email to: Bernard Geurts

  • MSc Thesis student: CFD - Thermal mixing
CFD- Thermal mixing

Supervisor: B.J. Geurt, E. Komen
Starting date: as soon as possible
Location: NRG

Read more...

  • MSc Thesis student: CFD - Two-phase flow mixing
CFD- Two-phase flow mixing

Supervisor: B.J. Geurt, E. Komen
Starting date: as soon as possible
Location: NRG

Read more...