Prelude. Cycle 1. Introduction. Cycle 2. Structure defines function. Cycle 3. Diversity of cortical functions is provided by inhibition. Cycle 4. Windows on the brain. Cycle 5. A system of rhythms: from simple to complex dynamics. Cycle 6. Synchronization by oscillation. Cycle 7. The brain's default state: self-organized oscillations in rest and sleep. Cycle 8. Perturbation of the default patterns by experience. Cycle 9. The gamma buzz: gluing by oscillations in the waking brain. Cycle 10. Perceptions and actions are brain state-dependent. Cycle 11. Oscillations in the "other cortex:" navigation in real and memory space. Cycle 12. Coupling of systems by oscillations. Cycle 13. The tough problem. References.

Rhythms of the brain

1980 Preface * 1999 Preface * 1999 Acknowledgements * Introduction * 1 Circular Logic * 2 Phase Singularities (Screwy Results of Circular Logic) * 3 The Rules of the Ring * 4 Ring Populations * 5 Getting Off the Ring * 6 Attracting Cycles and Isochrons * 7 Measuring the Trajectories of a Circadian Clock * 8 Populations of Attractor Cycle Oscillators * 9 Excitable Kinetics and Excitable Media * 10 The Varieties of Phaseless Experience: In Which the Geometrical Orderliness of Rhythmic Organization Breaks Down in Diverse Ways * 11 The Firefly Machine 12 Energy Metabolism in Cells * 13 The Malonic Acid Reagent ('Sodium Geometrate') * 14 Electrical Rhythmicity and Excitability in Cell Membranes * 15 The Aggregation of Slime Mold Amoebae * 16 Numerical Organizing Centers * 17 Electrical Singular Filaments in the Heart Wall * 18 Pattern Formation in the Fungi * 19 Circadian Rhythms in General * 20 The Circadian Clocks of Insect Eclosion * 21 The Flower of Kalanchoe * 22 The Cell Mitotic Cycle * 23 The Female Cycle * References * Index of Names * Index of Subjects

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/596B270197FE27DE5FABB598B6210622/S0025557200150892a.pdf/div-class-title-span-class-italic-the-geometry-of-biological-time-span-by-a-t-winfree-pp-544-dm68-corrected-second-printing-1990-isbn-3-540-52528-9-springer-div.pdf

The geometry of biological time , by A. T. Winfree. Pp 544. DM68. Corrected Second Printing 1990. ISBN 3-540-52528-9 (Springer)

Corticalgammaoscillations(20280Hz)predictincreasesinfocusedattention,andfailureingammaregulationisahallmark of neurological and psychiatric disease. Current theory predicts that gamma oscillations are generated by synchronous activity of fast-spiking inhibitory interneurons, with the resulting rhythmic inhibition producing neural ensemble synchrony by generating a narrow window for effective excitation. We causally tested these hypotheses in barrel cortex in vivo by targeting optogenetic manipulation selectively to fast-spiking interneurons. Here we show that light-driven activation of fast-spiking interneurons atvariedfrequencies (82200Hz) selectivelyamplifies gamma oscillations. Incontrast, pyramidal neuron activation amplifies only lower frequency oscillations, a cell-type-specific double dissociation. We found that the timing of a sensory input relative to a gamma cycle determined the amplitude and precision of evoked responses. Our data directly support the fast-spiking-gamma hypothesis and provide the first causal evidence that distinct network activity states can be induced in vivo by cell-type-specific activation.

/pdf/driving-fast-spiking-cells-induces-gamma-rhythm-and-controls-2nph5x6a2e.pdf

Driving fast-spiking cells induces gamma rhythm and controls sensory responses

Synchronized oscillations and inhibitory interneurons have important and interconnected roles within cortical microcircuits. In particular, interneurons defined by the fast-spiking phenotype and expression of the calcium-binding protein parvalbumin have been suggested to be involved in gamma (30-80 Hz) oscillations, which are hypothesized to enhance information processing. However, because parvalbumin interneurons cannot be selectively controlled, definitive tests of their functional significance in gamma oscillations, and quantitative assessment of the impact of parvalbumin interneurons and gamma oscillations on cortical circuits, have been lacking despite potentially enormous significance (for example, abnormalities in parvalbumin interneurons may underlie altered gamma-frequency synchronization and cognition in schizophrenia and autism). Here we use a panel of optogenetic technologies in mice to selectively modulate multiple distinct circuit elements in neocortex, alone or in combination. We find that inhibiting parvalbumin interneurons suppresses gamma oscillations in vivo, whereas driving these interneurons (even by means of non-rhythmic principal cell activity) is sufficient to generate emergent gamma-frequency rhythmicity. Moreover, gamma-frequency modulation of excitatory input in turn was found to enhance signal transmission in neocortex by reducing circuit noise and amplifying circuit signals, including inputs to parvalbumin interneurons. As demonstrated here, optogenetics opens the door to a new kind of informational analysis of brain function, permitting quantitative delineation of the functional significance of individual elements in the emergent operation and function of intact neural circuitry.

https://web.stanford.edu/group/dlab/media/papers/Sohal%20Nature%202009.pdf

Parvalbumin neurons and gamma rhythms enhance cortical circuit performance

Gamma rhythms are commonly observed in many brain regions during both waking and sleep states, yet their functions and mechanisms remain a matter of debate. Here we review the cellular and synaptic mechanisms underlying gamma oscillations and outline empirical questions and controversial conceptual issues. Our main points are as follows: First, gamma-band rhythmogenesis is inextricably tied to perisomatic inhibition. Second, gamma oscillations are short-lived and typically emerge from the coordinated interaction of excitation and inhibition, which can be detected as local field potentials. Third, gamma rhythm typically concurs with irregular firing of single neurons, and the network frequency of gamma oscillations varies extensively depending on the underlying mechanism. To document gamma oscillations, efforts should be made to distinguish them from mere increases of gamma-band power and/or increased spiking activity. Fourth, the magnitude of gamma oscillation is modulated by slower rhythms. Such cross-frequency coupling may serve to couple active patches of cortical circuits. Because of their ubiquitous nature and strong correlation with the "operational modes" of local circuits, gamma oscillations continue to provide important clues about neuronal population dynamics in health and disease.

/pdf/mechanisms-of-gamma-oscillations-4cjmph5v1o.pdf

Mechanisms of Gamma Oscillations

[PDF]  [Full Text]  [Abstract] , March 15, 2006; 90 (6): 1925-1938. Biophys. J. K. Morita, K. Tsumoto and K. Aihara Bidirectional Modulation of Neuronal Responses by Depolarizing GABAergic Inputs [PDF]  [Full Text]  [Abstract] , November 1, 2006; 18 (11): 2617-2650. Neural Comput. Whittington and N. J. Kopell D. D. Pervouchine, T. I. Netoff, H. G. Rotstein, J. A. White, M. O. Cunningham, M. A. Low-Dimensional Maps Encoding Dynamics in Entorhinal Cortex and Hippocampus

Neurons to Transient Inputs Phase-Response Curves Give the Responses of

It is now clear that electrical signaling via gap junctions plays a key role in the generation and maintenance of normal cortical activity in the adult brain Gap junctions consist of specific proteins (connexins and pannexins) that allow direct communication between the cytoplasm of two distinct neurons Gap junctions occur both between principal excitatory cells and between interneurons, particularly between interneurons of the same subclass Recent work now suggests that a number of different, anatomically discrete, gap junction-mediated networks may exist in the central nervous system that function to generate different patterns of synchronized neuronal activity

Gap Junctions and Neuronal Oscillations

There has recently been a large increase in the number of children placed in foster care in the United States and Europe. While this is the least worst scenario for those with a lack of appropriate biological care, it is recognised that these children are exposed to major stressors correlated with behavioural changes, particularly in the realm of social cognition into adulthood. Here we model foster care in rodents: rat pups are removed from their biological mother and placed with a non-genetically related dam. This prevented the entorhinal cortex from generating patterns of gamma rhythms required for normal parahippocampal function relevant to social interaction. These changes correlate with a reduction in NMDA receptor-mediated excitation, and changes in parvalbumin expression in	 interneurons. These data suggest that early life care delivered by a non-biological parent may disrupt social behaviour but, in contrast, generate neurobiological changes antagonistic to those currently associated with psychosis.

/pdf/cross-fostering-in-rodents-causes-region-specific-31su12b0je.pdf

Cross-fostering in rodents causes region-specific alterations in entorhinal cortical gamma rhythms associated with NMDA receptor dysfunction

on Entorhinal Cortical Neurons NR2B-Containing NMDA Autoreceptors at Synapses

The seminal in vivo work of Mircea Steriade and his colleagues has, as is always the case with the most insightful and creative scientists, raised many serious questions: questions, for example, of the detailed cellular and molecular mechanisms of the phenomena they discovered. In our tribute to this great investigator, we shall present some examples, based on our in vitro and modeling work, that shed light on some of his remarkable breakthroughs: the slow oscillation of sleep ( 70 Hz) oscillations.

Mark O. Cunningham

Papers

Neurons to Transient Inputs Phase-Response Curves Give the Responses of

Gap Junctions and Neuronal Oscillations

Cross-fostering in rodents causes region-specific alterations in entorhinal cortical gamma rhythms associated with NMDA receptor dysfunction

on Entorhinal Cortical Neurons NR2B-Containing NMDA Autoreceptors at Synapses

Fast oscillations in activated neocortical brain slices: An in vitro continuation of the pioneering in vivo studies of Mircea Steriade and colleagues