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.

Underlying principles are considered in the context of a variety of EEG and MEG data, including spontaneous activity and transient and steady-state evoked potentials. Several connections between general theoretical ideas concerning predictions of coherent spatial structure in neocortical dynamics, such as standing waves, and actual data are also discussed.

Sensory perception is fundamentally limited by the coding accuracy of sensory neural ensembles. Although a substantial body of work suggests that populations of sensory neurons exhibit correlated fluctuations that may bound the precision of neural coding, the extent to which these fluctuations extend across multiple cortical areas and interact with sensory coding during active animal behavior remain poorly understood. To examine the impact of correlated fluctuations on information coding and communication across sensory cortical areas, we imaged the Ca2+ activity of > 21,000 individual neurons across 11 neocortical areas in mice performing a Go/No-Go visual decision-making task. Multiple neocortical areas accurately encoded the visual stimulus, as well as the animal's decision to respond. Our analysis also revealed positively correlated noise fluctuations across neural populations in multiple neocortical areas. The mean strength of these noise correlations varied as a function of time across the visual stimulus presentation, delay, and response periods of our decision-making assay. Notably, sensory cortical neurons generally exhibited noise fluctuations that were more positively correlated at the start of visual stimulation, but then less so as a decision-making trial proceeded. Our results reveal that 60% of the total power of cortical variability stems from correlated fluctuations of neural populations spanning multiple distinct cortical areas. The strongest cortical fluctuation was a decision-coding activity mode that encompassed all brain areas under observation. We also found several fluctuation modes that encoded visual stimulus information but were shared across fewer brain areas. Overall, our analyses suggest that information regarding sensory stimuli and perceptual decisions are processed and shared between cortical areas through mutually non-interfering orthogonal channels. The timing of informative activity in these channels suggests that sensory information is first processed through intercommunications between multiple sensory areas, followed by a propagation of the final decision to all cortical areas involved.

An examination of how widely distributed and specialized activities of the brain are flexibly and effectively coordinated. A fundamental shift is occurring in neuroscience and related disciplines. In the past, researchers focused on functional specialization of the brain, discovering complex processing strategies based on convergence and divergence in slowly adapting anatomical architectures. Yet for the brain to cope with ever-changing and unpredictable circumstances, it needs strategies with richer interactive short-term dynamics. Recent research has revealed ways in which the brain effectively coordinates widely distributed and specialized activities to meet the needs of the moment. This book explores these findings, examining the functions, mechanisms, and manifestations of distributed dynamical coordination in the brain and mind across different species and levels of organization. The book identifies three basic functions of dynamic coordination: contextual disambiguation, dynamic grouping, and dynamic routing. It considers the role of dynamic coordination in temporally structured activity and explores these issues at different levels, from synaptic and local circuit mechanisms to macroscopic system dynamics, emphasizing their importance for cognition, behavior, and psychopathology. Contributors Evan Balaban, György Buzsáki, Nicola S. Clayton, Maurizio Corbetta, Robert Desimone, Kamran Diba, Shimon Edelman, Andreas K. Engel, Yves Fregnac, Pascal Fries, Karl Friston, Ann Graybiel, Sten Grillner, Uri Grodzinski, John-Dylan Haynes, Laurent Itti, Erich D. Jarvis, Jon H. Kaas, J.A. Scott Kelso, Peter König, Nancy J. Kopell, Ilona Kovács, Andreas Kreiter, Anders Lansner, Gilles Laurent, Jörg Lücke, Mikael Lundqvist, Angus MacDonald, Kevan Martin, Mayank Mehta, Lucia Melloni, Earl K. Miller, Bita Moghaddam, Hannah Monyer, Edvard I. Moser, May-Britt Moser, Danko Nikolic, William A. Phillips, Gordon Pipa, Constantin Rothkopf, Terrence J. Sejnowski, Steven M. Silverstein, Wolf Singer, Catherine Tallon-Baudry, Roger D. Traub, Jochen Triesch, Peter Uhlhaas, Christoph von der Malsburg, Thomas Weisswange, Miles Whittington, Matthew Wilson

Inhibitory interneurons are thought to play a crucial role in several features of neocortical processing, including dynamics on the timescale of milliseconds. Their anatomical and physiological characteristics are diverse, suggesting that different types regulate distinct aspects of neocortical dynamics. Interneurons expressing parvalbumin (PV) and somatostatin (SOM) form two non-overlapping populations. Here, I describe computational, correlational (neurophysiological) and causal (optogenetic) studies testing the role of PV and SOM neurons in dynamic regulation of sensory processing. First, by combining extra- and intracellular recordings with optogenetic and sensory stimulation and pharmacology, we have shown that PV cells play a key role in the generation of neocortical gamma oscillations, confirming the predictions of prior theoretical and correlative studies. Following this experimental study, we used a biophysically plausible model, simulating thousands of neurons, to explore mechanisms by which these gamma oscillations shape sensory responses, and how such transformations impact signal relay to downstream neocortical areas. We found that the local increase in spike synchrony of sensory-driven responses, which occurs without decreasing spike rate, can be explained by pre- and post-stimulus inhibition acting on pyramidal and PV cells. This transformation led to increased activity downstream, constituting an increase in gain between the two regions. This putative benefit of PV-mediated inhibition for signal transmission is only realized if the strength and timing of inhibition in the downstream area is matched to the upstream source. Second, we tested the hypothesis that SOM cells impact a distinct form of dynamics, sensory adaptation, using intracellular recordings, optogenetics and sensory stimulation. In resting neocortex, we found that SOM cell activation generated inhibition in pyramidal neurons that matched that seen in in-vitro studies. Optical SOM cell activation also transformed sensory-driven responses, decreasing evoked activity. In adapted responses, optical SOM cell inactivation relieved the impact of sustained sensory input, leading to increased membrane potential and spike rate. In contrast, SOM cell inactivation had minimal impact on sensory responses in a non-adapted neocortex, supporting the prediction that this class of interneurons is only recruited when the network is in an activated state. These findings present a previously unappreciated mechanism controlling sensory adaptation.

This book reviews recent progress in cortical development research, focusing on the mechanisms of neural stem cell regulation, neuronal diversity and connectivity formation, and neocortical organization. Development of the cerebral cortex, the center for higher brain functions such as cognition, memory, and decision making, is one of the major targets of current research. The cerebral cortex is divided into many areas, including motor, sensory, and visual cortices, each of which consists of six layers containing a variety of neurons with different activities and connections. As this book explains, such diversity in neuronal types and connections is generated at various levels. First, neural stem cells change their competency over time, giving sequential rise to distinct types of neurons and glial cells: initially deep layer neurons, then superficial layer neurons, and lastly astrocytes. The activities and connections of neurons are further modulated via interactions with other brain regions, such as the thalamocortical circuit, and via input from the environment. This book on cortical development is essential reading for students, postdocs, and neurobiologists.

The conference from which this book derives took place in Tsukuba, Japan in March 2004. The fifth in a continuing series of conferences, this one was organized to examine dynamic processes in "lower order" cognition from perception to attention to memory, considering both the behavioral and the neural levels. We were fortunate to attract a terrific group of con tributors representing five countries, which resulted in an exciting confer ence and, as the reader will quickly discover, an excellent set of chapters. In Chapter 1, we will provide a sketchy "road map" to these chapters, elu cidating some of the themes that emerged at the conference. The conference itself was wonderful. We very much enjoyed the vari ety of viewpoints and issues that we all had the opportunity to grapple with. There were lively and spirited exchanges, and many chances to talk to each other about exciting new research, precisely what a good confer ence should promote. We hope that the readers of this book will have the same experience—moving from careful experimental designs in the cogni tive laboratory to neural mechanisms measured by new technologies, from the laboratory to the emergency room, from perceptual learning to changes in memory over decades, all the while squarely focusing on how best to explain cognition, not simply to measure it. Ultimately, the goal of science is, of course, explanation. We also hope that the reader will come away absolutely convinced that cognition is a thoroughly dynamic, interactive system.