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Modern optical in vivo methods in neurophysiological research
Tomáška, Filip ; Novák, Ondřej (advisor) ; Elsnicová, Barbara (referee)
Accurate visualization of structures and events at subcellular level is one of the major challenges of current neuroscience. Optical methods based on fluorescence imaging were optimized to record and control neural activity, thus presenting a powerful approach complementary to historically dominant electrophysiological techniques. The employment of two-photon excitation enabled in vivo imaging of neurons up to 1 mm from the sample surface without causing significant photodamage. The application of methods of molecular biology has yielded protein-based genetically targetable indicators of neural activity, possessing performance comparable to the traditional organic dyes. Moreover, heterologous expression of microbial opsins proved capable of light-induced neural excitation or silencing in a single-component manner. The combination of these optogenetic tools offers two-way control over neuronal populations with single cell resolution. If coupled with calcium or voltage fluorescent indicators and transgenic animal models, such systems represent a non- invasive, all-optical tool for simultaneous control and imaging of specific neuronal subtypes. Its application supported by electrical recordings may finally provide the data necessary for the uncovering of fundamental principles of neural functioning.
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Modern optical in vivo methods in neurophysiological research
Tomáška, Filip ; Novák, Ondřej (advisor) ; Elsnicová, Barbara (referee)
Accurate visualization of structures and events at subcellular level is one of the major challenges of current neuroscience. Optical methods based on fluorescence imaging were optimized to record and control neural activity, thus presenting a powerful approach complementary to historically dominant electrophysiological techniques. The employment of two-photon excitation enabled in vivo imaging of neurons up to 1 mm from the sample surface without causing significant photodamage. The application of methods of molecular biology has yielded protein-based genetically targetable indicators of neural activity, possessing performance comparable to the traditional organic dyes. Moreover, heterologous expression of microbial opsins proved capable of light-induced neural excitation or silencing in a single-component manner. The combination of these optogenetic tools offers two-way control over neuronal populations with single cell resolution. If coupled with calcium or voltage fluorescent indicators and transgenic animal models, such systems represent a non- invasive, all-optical tool for simultaneous control and imaging of specific neuronal subtypes. Its application supported by electrical recordings may finally provide the data necessary for the uncovering of fundamental principles of neural functioning.
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Mechanisms of growth of the cardiac conduction system
Skuhrová, Kristýna ; Sedmera, David (advisor) ; Elsnicová, Barbara (referee)
The ability to produce regular rhythm and independence of nervous system and are some of the features of the cardiac conduction system. The conduction system comprises the sinoatrial node, internodal tracts, the atrioventricular node, the atrioventricular (His) bundle, its right and left branches, and the terminal network of Purkinje fibers. However, this system is frequently the cause of the cardiac rhythm disorders, i.e., arrhythmias. There are many unanswered questions about the conduction system, even though its development is closely connected to the growth of the whole heart. The heart undergoes many dramatic changes during its development, such as modification of linear heart tube into the mature four-chamber organ. Looping and forming chambers cause change of localization first "pacemaker" from the caudal end of the heart tube to the area of the right atrium. Prenatal growth of the heart is based upon cell proliferation or hyperplasia. The cell divisions are rapidly stopped soon after birth and the cells start to grow by increase in volume, i.e., hypertrophy. The cells of some species can expand hyperplasia or hypertrophy in early postnatal period. The mouse is one of the organisms with the cell expansion provided by combination of proliferation and hypertrophy. Most of the adult...
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