Optical Imaging Of Brain Function And Metabolism

• . . . . At last the doctor will be freed from the tedious interpretation of screens and photographs. Instead, he will examine and scan through his patient directly. Wearing optical-shutter spectacles and aiming a pulsed laser torch, he will be able to peer at the beating heart, study the movement of a joint or the flexing of a muscle, press on suspect areas to see how the organs beneath respond, check that pills have been correctly swallowed or that an implant is savely in place, and so on. A patient wearing white cotton or nylon clothes that scatter but hardly absorb light, may not even have to undress . . . . •. David Jones, Nature (1990) 348:290 Optical imaging of the brain is a rapidly growing field of heterogenous techniques that has attracted considerable interest recently due to a number of theoretical advantages in comparison with other brain imaging modalities: it uses non ionizing radiation, offers high spatial and temporal resolution, and supplies new types of metabolic and functional information. From a practical standpoint it is important that bedside examinations seem feasible and that the implementations will be considerably less expensive compared with competing techniques. In October 1991, a symposium was held at the Eibsee near Garmisch, Germany to bring together the leading scientists in this new field.

This volume covers the latest developments in optical imaging of the brain which is becoming an increasingly important functional neuroimaging method. Optical intrinsic signals offer unrivaled temporal and spatial resolution of functional measurements of the exposed brain cortex in animals and humans. Near-infrared spectroscopy and imaging ap proaches permit the noninvasive functional assessment of the human brain at bedside. Main advantages of these optical techniques are the biochemical specificity of the meas urements and the potential of measuring correlates of intracellular and intravascular oxy genation simultaneously. Recent data indicate that one may also measure a more direct correlate of neuronal activity associated with changes in light scattering. In this volume, recent technical progress of the optical method is covered as well as the physiological basis of the measurements. In simultaneous studies, near-infrared spec troscopy measurements are directly compared to other functional methods, especially PET and fMRI and examples are given for new applications of the NIRS-method. Based on re sults obtained with optical methods and other functional techniques the latest in our under standing of the coupling of neuronal activity and cerebral blood flow response is reviewed. This is an important basis for a better understanding of all functional neuroi maging methods which rely on neurovascular coupling such as PET, SPET and fMRI. Fi nally the optical method is put into the perspective of presently available functional neuroimaging methods including fMRI, PET, MEG and EEG.

These are exciting times for the field of optical imaging of brain function. Rapid developments in theory and technology continue to considerably advance understanding of brain function. Reflecting changes in the field during the past five years, the second edition of In Vivo Optical Imaging of Brain Function describes state-of-the-art techniques and their applications for the growing field of functional imaging in the live brain using optical imaging techniques. New in the Second Edition: Voltage-sensitive dyes imaging in awake behaving animals Imaging based on genetically encoded probes Imaging of mitochondrial auto-fluorescence as a tool for cortical mapping Using pH-sensitive dyes for functional mapping Modulated imaging Calcium imaging of neuronal activity using 2-photon microscopy Fourier approach to optical imaging Fully updated chapters from the first edition Leading Authorities Explore the Latest Techniques Updated to reflect continuous development in this emerging research area, this new edition, as with the original, reaches across disciplines to review a variety of non-invasive optical techniques used to study activity in the living brain. Leading authorities from such diverse areas as biophysics, neuroscience, and cognitive science present a host of perspectives that range from a single neuron to large assemblies of millions of neurons, captured at various temporal and spatial resolutions. Introducing techniques that were not available just a few years ago, the authors describe the theory, setup, analytical methods, and examples that highlight the advantages of each particular method.

If a picture is worth a thousand words, then dynamic images of brain activity certainly warrant many, many more. This book will help users learn to decipher the dynamic imaging data that will be critical to our future understanding of complex brain functions. In recent years, there have been unprecedented methodological advancements in the imaging of brain activity. These techniques allow the measurement of everything from neural activity (e.g., membrane potential, ion ?ux, neurotransmitter ?ux) to energy metabolism (e.g., glucose consumption, oxygen consumption, creatine kinase ?ux) and functional hyperemia (e.g., blood ?ow, volume, oxygenation). This book deals with a variety of magnetic resonance, electrophysiology, and optical methods that are often used to measure some of these dynamic processes. All chapters were written by leading experts, spanning three continents, specializing in state-of-the-art methods. Brie?y, the book has ?ve sections. In the introductory section, there are two chapters; the ?rst one contains a brief pre- ble to dynamic brain imaging and the other presents a novel, analytical approach to processing of dynamically acquired data. The second section has four chapters and delves into a wide range of optical imaging methods. I am privileged to include a chapter from Lawrence B. Cohen, considered by many to be the authority on optical imaging and spectroscopy, both in vitro and in vivo [Cohen LB (1973) Physiol Rev.

The application of optical methods for investigating neocortical circuit dynamics has greatly expanded in recent years, providing novel insights into the fascinating world of brain function. Optical Imaging of Neocortical Dynamics presents a guide to these indispensible tools, which cover a broad range of spatiotemporal scales and a large variety of signaling aspects, ranging from voltage changes to metabolic states. This detailed volume specifically explores methods that are applied in experiments on living brains (in vivo) and that relate to functional properties on the spatial scale of cortical circuits. Beginning with an introductory section that focuses on physical fundamentals of optical imaging as well as molecular tools used for in vivo optical imaging and optogenetic control, the book continues with the most relevant methods and their applications to investigate changes in neuronal and glial activity states as well as optical imaging methods probing metabolic states. Written for the Neuromethods series, this volume contains the kind of detail and key implementation advice that ensures successful results in the lab. Practical and easy to use, Optical Imaging of Neocortical Dynamics serves as an ideal guide for researchers who aim to apply these highly valuable tools to their own neuroscientific studies.

Monitoring brain function with light in vivo has become a reality. The technology 33 of detecting and interpreting patterns of reflected light has reached a degree of 34 maturity that now permits high spatial and temporal resolution visualization at both 35 the systems and cellular levels. There now exist several optical imaging methodolo- 36 gies, based on either hemodynamic changes in nervous tissue or neurally induced 37 light scattering changes, that can be used to measure ongoing activity in the brain. 38 These include the techniques of intrinsic signal optical imaging, near-infrared optical 39 imaging, fast optical imaging based on scattered light, optical imaging with voltage 40 sensitive dyes, and two-photon imaging of hemodynamic signals. The purpose of 41 this volume is to capture some of the latest applications of these methodologies to 42 the study of cerebral cortical function. 43 This volume begins with an overview and history of optical imaging and its use 44 in the study of brain function. Several chapters are devoted to the method of intrin- 45 sic signal optical imaging, a method used to record the minute changes in optical 46 absorption due to hemodynamic changes that accompanies cortical activity. Since the 47 detected hemodynamic changes are highly localized, this method has excellent 48 spatial resolution (50–100 μm ), a resolution sufficient for visualization of fundamen- 49 tal modules of cerebral cortical function.