RESEARCH PROJECTS
LIDER project
MNiSW project
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Project description
The thematic area of the project is Fourier domain Optical Coherence Tomography (FdOCT)
imaging of neural tissue functioning. The research focuses on development of methods
and devices for activity detection in model neurons and in the retina. The study
is a contribution to functional OCT which uses Optical Coherence Tomography techniques
for detection of biological tissue functioning.
The project is carried at the
Medical Physics Group,
Department of Biophysics and Medical Physics,
Faculty of Physics, Astronomy and Informatics,
Nicolaus Copernicus University,
in collaboration with the Department of Biophysics,
Faculty of Biology and Earth Sciences,
Nicolaus Copernicus University, Poland.
The funds for project realization were obtained from the
National Centre for Research and Developmnet, LIDER Programme.
The project consists of two research aims:
1) development of low coherence interferometry methods for detection of activity in model neurons,
2) development of FdOCT reflectometry techniques and instrumentation for detection of neural activity in the retina.
Aim 1. Development of low coherence interferometry methods
for detection of activity in model neurons
The main hypothesis of the research is that changes in optical and mechanical
properties of neurons induced by their activation can be detected by Fourier
domain OCT technology. These changes include scattering properties, birefringence,
absorption and volume changes (shortening, shrinkage, swelling). Although OCT
has been successfully used for detection of functioning of different neural tissues
little has been done for understanding possibilities and limitations of OCT methods
for detection of neural activity. The purpose of this study is to investigate how
neuronal activity influences different parameters of the OCT signal and to identify
possible detection techniques and methods for further development of functional OCT.
Changes in the OCT signal may be related to intensity variations and polarization
changes of the scanning beam of light, to the phase shifts of the interference signal,
or to the spectral changes of light propagating inside the object. This suggests four
OCT detection techniques which perhaps could be applied for imaging of activity
of neurons: OCT reflectometry, polarization sensitive OCT, phase sensitive OCT
and spectroscopic OCT.
This project focuses on development of reflectometry and phase sensitive methods.
Neurons partially or completely isolated from the nervous system of American cockroach
will serve as a model.
Aim 2. Development of FdOCT reflectometry techniques and instrumentation
for detection of neural activity in the retina
The main assumption of this research subject is that the neural activity may
change optical properties of retinal tissue which can be detected by
high speed, high resolution OCT with Fourier domain detection. Visual processes
(conversion of light into electrical signals during phototransduction) and propagation
of electrical pulses in neural cells can cause changes in reflectivity of
different retinal layers. These functional changes can be estimated by a very
sensitive analysis of the intensity variations of the OCT signal.
This project focuses on development of methods for reflectivity changes detection
in the photoreceptor layer. The function of the photoreceptor layer can be impaired
by degenerative retinal diseases like age related macular degeneration (AMD).
Study on reflectivity changes in the nerve fiber layer and in the optic nerve
head will be also undertaken. Pathology development in these structures can be
a result of eye diseases (e.g. glaucoma) or central nervous system diseases
(e.g. multiple sclerosis).
There are several motivations to undertake studies on functional OCT in the retina.
Eye diseases are a growing problem in industrialized countries with increased life
expectancy. Diseases like age related macular degeneration (AMD) or glaucoma are
leading causes of legal blindness. However, their pathogenesis and causes of progression
remain unknown in most cases. More interestingly, retinal health is dependent on
condition of other vital systems of the human organism, e.g. the central nervous
system of which the retina is a part, or cardiovascular system. Retinal disease
may be a symptom of development of pathology in these systems. Two important
examples are diabetes mellitus causing diabetic retinopathy and multiple sclerosis
causing optic neuritis.
Development of sight threatening diseases whether connected to the eye only or
being a result of other pathology, influences retinal morphology and physiology.
The methods of detection of changes in both of them would constitute a powerful
tool for elucidating disease pathogenesis and for early diagnosis and monitoring
disease progression as well as effectiveness of medical procedures.
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