Development of a Novel High Resolution Optical Neuroimaging Method
Koski, Mikko (2010)
2010
Sähkötekniikan koulutusohjelma
Tieto- ja sähkötekniikan tiedekunta
Luonnontieteiden ja ympäristötekniikan tiedekunta
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Hyväksymispäivämäärä
2010-11-03
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201011161367
https://urn.fi/URN:NBN:fi:tty-201011161367
Tiivistelmä
The purpose of this thesis was to develop new high resolution neuroimaging method, which allows detection of neuronal activity from neuronal tissue samples in laboratory conditions. Neuroimaging methods utilizing high spatial and temporal resolution pro- vide highly useful information about the functioning and information processing especially in functional neuronal networks.
High resolution neuroimaging methods for monitoring the functioning of neuronal tissue have been developed. These methods are based on the specimen fluorescence, which is achieved by using fluorescent dyes, which are harmful for the cells. However, the studied new neuroimaging method is based purely on the natural functioning of the neuronal tissue, without using any dye substances. Method utilizes the microscope observations of fast intrinsic optical signals (FIOS), which arise from the natural action potential induced changes in the optical properties of the neuronal cells.
Based on the literature review, in which some successful FIOS measurements were found, the theories concerned with the work are thoroughly described in this thesis. However, earlier measurements employed only single photodiode elements. In this the- sis, the single photodiode element is replaced by digital imaging sensor, which is able to provide spatial image of the functioning of the neuronal network. Regardless of the extensive literature search, no earlier studies with high resolution sensor and using same type of specimens were found.
The measurements related to this thesis were conducted by simultaneously imaging and electrically measuring functional networks of neuronal cells derived from human embryonic stem cells. Imaging was conducted using optical light microscopy equipped with a scientific grade CCD imaging sensor, whereas electrical measurements were conducted using microelectrode array (MEA) technique, which provided spatial measuring information. MEA data was used to verify the imaging results and thus the functioning of the developed method.
The measurements and the development task of this new neuroimaging method failed primarily due to the bad condition of the imaging equipment, especially the mi- croscope and the illumination used. Unfortunately, it was not possible to fix these issues within the resources allocated for this thesis.
However, this thesis focused to cover thoroughly the theory of the studied imaging method and the requirements related to it. Also a plan was made for the required imaging equipment as well as for implementing the method itself. Based on this thesis and with proper devices, the proposed imaging method should be straightforward to implement. /Kir10
High resolution neuroimaging methods for monitoring the functioning of neuronal tissue have been developed. These methods are based on the specimen fluorescence, which is achieved by using fluorescent dyes, which are harmful for the cells. However, the studied new neuroimaging method is based purely on the natural functioning of the neuronal tissue, without using any dye substances. Method utilizes the microscope observations of fast intrinsic optical signals (FIOS), which arise from the natural action potential induced changes in the optical properties of the neuronal cells.
Based on the literature review, in which some successful FIOS measurements were found, the theories concerned with the work are thoroughly described in this thesis. However, earlier measurements employed only single photodiode elements. In this the- sis, the single photodiode element is replaced by digital imaging sensor, which is able to provide spatial image of the functioning of the neuronal network. Regardless of the extensive literature search, no earlier studies with high resolution sensor and using same type of specimens were found.
The measurements related to this thesis were conducted by simultaneously imaging and electrically measuring functional networks of neuronal cells derived from human embryonic stem cells. Imaging was conducted using optical light microscopy equipped with a scientific grade CCD imaging sensor, whereas electrical measurements were conducted using microelectrode array (MEA) technique, which provided spatial measuring information. MEA data was used to verify the imaging results and thus the functioning of the developed method.
The measurements and the development task of this new neuroimaging method failed primarily due to the bad condition of the imaging equipment, especially the mi- croscope and the illumination used. Unfortunately, it was not possible to fix these issues within the resources allocated for this thesis.
However, this thesis focused to cover thoroughly the theory of the studied imaging method and the requirements related to it. Also a plan was made for the required imaging equipment as well as for implementing the method itself. Based on this thesis and with proper devices, the proposed imaging method should be straightforward to implement. /Kir10