Here, we describe and illustrate our methods for recording multiple single neurons and local field potential in behaving rodent; fabrication of microdrives for chronic recordings with silicon probes and our surgical procedures.
Here, we demonstrate that seizure-triggered, feedback TES can dramatically reduce spike-and-wave episodes in a rodent model of generalized epilepsy. Closed-loop TES can be an effective clinical tool to reduce pathological brain patterns in drug-resistant patients.
We introduce a new head-fixed paradigm where all changing stimuli are controlled by the locomotion of the mouse. We demonstrate how division of labor between perisomatic (parvalbumin (PV) expressing) or dendrite-targeting (somatostatin (SOM) expressing) interneurons affect the rate, bursting and timing of pyramidal neurons, using optogenetic methods combined with large-scale silicon probe recordings of unit activity.
Because of their ubiquitous nature and strong correlation with the “operational modes” of local circuits, gamma oscillations provide important clues about neuronal population dynamics in health and disease. Here, we review the cellular and synaptic mechanisms underlying gamma oscillations and outline empirical questions and controversial conceptual issues.
Here we propose that mechanisms of memory and planning have evolved from mechanisms of navigation in the physical world and hypothesize that the neuronal algorithms underlying navigation in real and mental space are fundamentally the same. We review experimental data in support of this hypothesis and discuss how specific firing patterns and oscillatory dynamics in the entorhinal cortex and hippocampus can support both navigation and memory.
Today's cognitive science largely follows the tradition of empiricism by looking for correspondences between 'stimuli' in the external world and their responses or 'representations' in the brain. This approach works well (sort of) in primary sensory areas but typically fails when cognitive or emotional mechanisms are to be investigated. The empiricist method is a bit like learning words in a foreign language, i.e., collecting correspondences between a known and a new language. The initial progress is fast. One can get by in a foreign country with just 100 words of vocabulary. However, when it comes to truly understanding a language, one needs to know the grammar, the syntactical rules that allow for the generation of virtually infinite combinations from finite numbers of lexical elements. Syntax allows for the segmentation of information into a temporal progression of discrete elements with ordered and hierarchical relationships (e.g. tempo, punctuation, etc), resulting in congruent interpretation of meaning. We endeavor to study the syntax, and not just the vocabulary, of the brain.
Our working hypothesis is that in brain networks, especially those serving cognitive functions, the packaging and segmentation of neural information is supported by the numerous self-organized rhythms the brain generates. Brain rhythms allow for temporal correlations to occur at multiple time scales which can be mathematically defined. Rhythms and other non-rhythmic 'chunking' patterns can be thought of as 'order parameters' and are often recognized in the local field potentials. These mesoscopic patterns are telltale signs of the grouping and segregation of transient cell assemblies and their evolving sequences.
Brain oscillations form a hierarchical structure: slower oscillations phase-modulate the power of faster rhythms. These mesoscopic temporal structures (i.e., brain oscillations) have been fully preserved throughout mammalian evolution and have constrained both the evolutionary and ontogenetic scaling of brain structures. Some rhythms are region-specific while others are ubiquitous. Oscillations are robust and easily quantifiable phenotypes and various brain systems have unique constellations of oscillations. Twin studies show just how tightly genetic factors control brain rhythms. In some cases, both the genes and mode of inheritance have been determined. Every psychiatric disease is associated with some kind of rhythm problem. Importantly, mice and rats have brain oscillations with the same pharmacological profiles as humans, and therefore serve as important targets for drug discovery. Our actions and perceptions are strongly affected by the constellation of rhythms. For example, rhythms can strongly bias which part of the text you are reading now will be remembered tomorrow.
Work in our lab focuses largely on the generation of these various oscillations, their spatial and temporal relationships, and the role of inhibition in the enforcement of syntactic rules. We monitor large-scale neuronal firing patterns and the local fields they generate in behaving rodents in order to relate the assembly patterns and order parameters to overt and covert behaviors. Perturbation of the various oscillations or the neuronal components that give rise to these rhythms--using closed-loop optogenetics and other methods--is a complementary approach. The main focus of our investigations is the hippocampus and we reach out from this structure to its numerous cortical and subcortical partners.
The advantage of our 'inside-out' approach to brain function is that it is free of philosophical connotations and takes brain mechanisms as independent variables, as opposed to attempts to finding 'correspondences' or 'representations' between subjectively derived categories and boundaries and brain responses. If you are still skeptical of our approach, just ask any practicing psychiatrist how well the boundaries set up by DSM-IV translate to the diseases they treat. We submit that a syntactical approach to brain function is an alternative, and perhaps more effective, strategy
Rhythms of the Brain, György Buzsáki
2012 |
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David Sullivan, Shigeyoshi Fujisawa, Rony Eichler, Lisa Roux, Antal Berényi, Brendon Watson, John Long, Andres Grosmark, György Buzsáki, Zoltán Somogyvári, Celina Caban-Nieves, Adrien Peyrache, Thomas Allen, Eran Stark, Jagdish Patel, Marie LaCroix, Esther Holleman. Missing: Mariano Belluscio, Kenji Mizuseki, Gautam Agarwal |
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2009 - Alumni Reunion |
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2008 |
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| Jagdish Patel, Shigeyoshi Fujisawa, Kamaran Diba, Anton Sirota, György Buzsáki, Asohan Amarasingham, Sean Montgomery, Kenji Mizuseki, Simal Ozen, Mariano Belluscio, Marie Vandecasteele, Andres Grosmark, Caroline Geisler , Pascale Quillicini, David Sullivan, Eva Pastalkova |
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2006 |
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2006 |
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| Celina Caban-Nieves, Kamaran Diba, Eva Pastalkova , Caroline Geisler , Asohan Amarasingham, Jagdish Patel, Kenji Mizuseki, Simal Ozen, György Buzsáki, David Sullivan, Anton Sirota, David Robbe, Sebastien Royer, Shigeyoshi Fujisawa, Sean Montgomery, Pascale Quillicini |
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2005 |
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| Eva Pastalkova , Sean Montgomery, György Buzsáki, Pavel E. Rueda-Orozco, Anton Sirota, Simal Ozen, Yoshikazu Isomura, David Robbe, Kenji Mizuseki, Dirk Isbrandt, Sebastien Royer, Stephan Marguet, Shazu Sakata |
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2002 |
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2000 |
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Front row: Hajime Hirase, Erzsebet Borok, Gyorgy Buzsaki, Darrell Henze, Lisa Marshall. Back row: Derek Buhl, Xavier Leinekugel, Ken Harris, Jozsef Csiicsvari. Missing: Zoltan Nadasdy, Andras Czurko , George Dragoi |
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1995 |
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1994 |
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| Man-Gee Lee, Adam Kandel, Zoltan Nadasdy, Daniel Carpi, Aarne Ylinen, Markku Penttonen, Attila Sik, György Buzsáki, Melissa Hsu |
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Rhythms of the Brain.
Buzsáki, G. Rhythms of the Brain. Oxford University Press (2006)
Animal Learning.
Buzsáki, G. Natura Press, Budapest, 1984, (in Hungarian) pp.1-142.
http://www.amazon.com/Rhythms-Brain-Gyorgy-Buzsaki/dp/0199828237
Temporal Coding in the Brain
Synaptic plasticity in the hippocampus.
Electrical activity of the archicortex.
Hilar mossy cells: functional identification and activity in vivo. In: The Dentate Gyrus: a comprehensive guide to structure function and clinical applications
Henze, DA, Buzsáki G. (Helen E. Scharfman, ed.) 2007. 787 pages
Inhibition: Diversity of cortical functions.
Buzsáki, G. In: H.L. Roediger III, Y. Dudai , SM Fitzpatrick (eds) Science of Memory: Concepts. Oxford University Press. 2007 pp. 285-289.
Maintenance and modification of firing rates and sequences in the hippocampus: does sleep play a role?
Buzsáki, G. Carpi, D., Csicsvari, J., Dragoi, G, Harris, K.D., Henze, D. A., Hirase, H. In: Maquet, P., Smith, C., and Stickgold, R. (eds). Sleep and Plasticity. Oxford University Press., Oxford. 2003. Pp. 247-270.
Single cell contribution to network activity in the hippocampus.
Henze, D. A., and Buzsáki, G. In: T. Ono, G. Matsumoto, R. R. Llinas, A. Berthoz, R. Norgren, H. Hishijo, R. Tamura (eds) Cognition and emotion in the brain. Excerpta Medica. Ingernational congress series 1250. 2003. pp. 161-182.
The cellular synaptic generation of EEG. In: Current Practice of Clinical Encephalography.
Buzsáki, G., Traub, R. D. and Pedley, T., (J. S. Ebersole and T. A. Pedley, eds). Lippincott-Williams and Wilkins, Philadelphia (3rd edition), 2003. pp. 1-11.
Network oscillations in the hippocampal formation.
Buzsáki, G. In: Frontiers of Life. D. Baltimore, R., Dulbecco, F. Jacob, R. Levi-Montalcini (eds). Academic Press, New York. 2000. Volume 4. Pp 575-588.
Two-phase computational model training long-term memories in the entorhinal-hippocampal region.
Lörincz, A. and Buzsáki, G. Annals of the New York Academy of Sciences 911:83-111, 2000.
GABAergic interneuronal networks in the hippocampus.
Buzsáki, G., Dragoi, G., Csicsvari, J., Hirase, H., Czurko, A. and Henze D. (2000) D. L. Martin and Olsen, R. W. (eds) GABA in the Nervous System. Lipincott Williams & Wilkins, Philadelphia. Pp. 317-336.
State-dependent changes in network activity of the hippocampal formation.
Chrobak, J. and Buzsáki, G. In: Handbook of Behavioral State Conrol: Cellular and Molecular Mechanism. R. Lydic and H. A. Baghdoyan (Eds.) CRC Press, Boca Raton, FL.1999. pp. 349-362.
Oscillazioni di reti neuronali nell’ippocampo (Network oscillations in the hippocampal formation)
Buzsáki, G., D. Baltimore, R., Dulbecco, F. Jacob, R. Levi-Montalcini (eds). Frontiere Della Vita, Instituto della Enciclopedia Italiana, vol. III. (537-548), 1999.
Extracellular recording and analysis of electrical activity: from single cells to ensembles.
Nadasdy, Z., Csicsvari J, Penttonen, M. and Buzsáki, G. (1998) In: Neuronal ensembles: Strategies for recording and decoding. (H. Eichenbaum and J. L. Davis, eds.) Wiley-Liss, New York. Pp. 17-55.
The constraint of synaptic potentiation and memory formation by entorhinal-hippocampal network dynamics.
Chrobak, J. and Buzsáki, G. In: Long-term potentiation. Vol. 3. HM. Baudry and J. L. Davis (Eds.) MIT Press, Boston, 1997. Pp. 215-232.
Generation of EEG.
Buzsáki, G. and Traub, R. D. In: Epilepsy: a comprehensive textbook. (J. Engel, Jr. and T. A. Pedley, eds). Lippincott-Raven Press (1996)
Structural impairment of hippocampal neurons following a single epileptic afterdischarge.
Horváth, Z. Hsu, M., Pierre, E., Vadi, D., Gallyas, F. and Buzsáki, G. In: Chronic epilepsy models (U. Heinemann and J. Engel eds.). Raven, NY (1996)
Memory consolidation in the "non-aroused" brain: a physiological perspective.
Buzsáki, G., Bragin, A., Chrobak, J. J. and Nadasdy, Z. In: Maturational windows and cortical plasticity: is there a reason for an optimistic view? (B. Julesz, G. Cowan and I. Kovacs, eds.), SFI Studies in the Sciences and Complexity. Addison-Wesley, (1995)
Short-term and long-term changes in the postischemic hippocampus
Hsu, M, Sik, A., Gallyas, F., Horvath, Z., Buzsáki, G. (V. Luine and C. F. Harding, eds.) Annals of the NY Academy of Sciences, NY vol. 743: 121-140, (1994)
Oscillatory and intermittent synchrony in the hippocampus: relevance to memory trace formation.
Buzsáki, G., Bragin, A., Chrobak, J. J. , Nadasdy, Z., Sik, A. , Hsu, M. and Ylinen, A. In: Temporal Coding in the Brain (G. Buzsáki, R. Llinas, A. Singer, W. Berthoz and Y. Christen), Springer, Heidelberg, pp. 145-172, (1994).
Kindling-induced changes of protein kinase C levels in hippocampus and neocortex.
Buzsáki, G., Hsu, M., Horvath, Z., Hogsburgh, K., Sundsmo, M., Masliah, E. and Saitoh, T. In: Molecular Neurobiology of Epilepsy (G. Avanzini, E. A. Cavalheiro, U. Heinemann, C. Wasterlain and J. Engel., Jr., eds). Elsevier, Amsterdam, pp. 279-284, (1992)
Network properties of the thalamic clock: role of oscillatory behavior in mood disorders.
Buzsáki, G. In: Induced rhythms of the brain (E. Basar and T. H. Bullock, eds.) Birkhäuser, Boston, pp. 235-250, (1992)
Neuronal grafts in epilepsy research.
Buzsáki, G. and Gage, F. H. In: Surgery of Epilepsy (H. Lüders, ed.), Raven Press, New York, pp. 737-740, (1992)
Fetal tissue grafts modulate neuronal excitability in a chronic model of epilepsy.
Buzsáki, G. and Gage, F. H. In: Neurotransmitters in epilepsy (G. Avanzini, J. Engel, Jr., R. Fariello and U. Heinemann, eds.). Elsevier, Amsterdam. pp. 271-282, (1992).
Excitatory amino acid receptors in human temporal lobe epilepsy and in animal models.
Geddes, J. W., Ulas, J., Buzsáki, G., and Cotman, C. W. In: Excitatory Amino Acids (B. S. Meldrum, F. Moroni, and J. H. Woods, eds.). Raven Press, New York, pp. 749-757, (1991)
Physiological function of granule cells: a hypothesis. In: The hippocampal dentate gyrus and its role in seizures
Buzsáki, G. and Czeh, G. (C. E. Ribak, C. M. Gall and I. Mody, eds.) Elsevier, Amsterdam, pp. 281-290, (1991)
Long-term potentiation: Does it happen in the normal brain? When and how?
Buzsáki, G. and Gage, F. H. In: Memory Mechanisms: A tribute to G.V. Goddard, (M. Corballis, K. White and W. C. Abraham eds.) Erlbaum, N.J. pp. 79-102, (1991)
Role of basal forebrain cholinergic system in cortical activation and arousal.
Buzsáki, G. and Gage, F. H. In Activation to Acquisition: Functional Aspects of the Basal Forebrain Cholinergic System. (R. T. Richardson ed.) Birkhauser, Boston, pp. 115-133, (1991)
Reconstruction of the basal forebrain cholinergic circuits of the aged and yound brain damaged rat.
Gage, F. H., Buzsáki, G. and Tuszynski, M. H. In: Current Communications in Molecular Biology: the Molecular Biology of Alzheimer's Disease, pp. 149-154, (1990)
Experimental therapeutic approaches: Intracerebral grafting and neurotrophic factors. In: Alzheimer's Disease: Treatment and Long-term Management.
Gage, F. H. and Buzsáki, G. (J. L. Cummings and B. L. Miller, eds.) Dekker, New York. pp.353-370, (1990)
Cognitive impairments in aging: therapeutic approaches.
Gage, F. H., Chen, K. S., Buzsáki, G. and Higgins, G. In: Mechanisms of memory (L. J. Squire, ed.) Schattauer Verlag, Berlin, (1990)
Spatial organization of physiological activity in the hippocampal formation: relevance to memory formation.
Buzsáki, G., Chen,L. S. and Gage, F. H. In: Progress in Brain Research. (J. Storm-Mathisen, H. Zimmer and O. P. Ottersen eds.) Understanding the brain through the hippocampus. Elsevier, Amsterdam, pp. 257-268, (1990)
NGF-dependent sprouting and regeneration in the hippocampus.
Gage, F. H., Buzsáki, G. and Amstrong, D. M. In: Progress in Brain Research, (J. Storm-Mathisen, H. Zimmer and O. P. Ottersen eds.) Understanding the brain through the hippocampus. Elsevier, Amsterdam, pp. 357-370, (1990)
Parallel activation of thalamic and cortical neurons by brainstem and basal forebrain cholinergic systems.
Steriade, M. and Buzsáki, G. In: Brain Cholinergic Systems (M. Steriade and D. Biesold, eds.) Oxford University Press, Oxford, pp. 3-64,(1990)
Survival, growth and function of damaged cholinergic neurons.
Gage, F. H., Tuszynski, M. H., Chen, K. S., Armstrong, D.and Buzsáki, G. In: Central cholinergic synaptic transmission. (M. Frotscher and J. Misgeld, eds.) Springer: Berlin, pp. 259-274, (1989)
CNS grafting: the potential mechanism of action. In: Neural regeneration and Transplantation.
Gage, F. H., and Buzsáki, G. (F.J. Seil ed.) Alan R. Liss, New York. pp. 211-226, (1989)
Pathophysiology of the subcortically deafferented hippocampus. In: Neuronal Grafting and Alzheimer's disease.
Buzsáki, G. and Gage, F. H. (F. H. Gage, A. Privat and Y. Christen, eds.) Springer: Berlin, pp. 101-119, (1989)
The cholinergic nucleus basalis: a key structure in neocortical arousal.
Buzsáki, G. and Gage, F. H. In: Central cholinergic synaptic transmission. (M. Frotscher and J. Misgeld, eds.) Springer: Berlin, pp. 159-171, (1989)
Neuronal grafting in the adult hippocampal formation.
Gage, F. H. and Buzsáki, G. In: The hippocampus-New vistas (V. Chan-Palay and C. Kohler, eds.) Alan R. Liss, New York pp. 237-255, (1989)
Restoration and deterioration of function by brain grafts in the septohippocampal system.
Buzsáki, G., Freund, T., Bjorklund, A. and Gage, F. H. In: Progress in Brain Research (D. M. Gash and J. R. Sladek Jr. eds.). 78: 69-77, (1988)
Neural grafts: Possible mechanisms of action. In: Neural Plasticity: A Lifespan Approach.
Buzsáki, G. and Gage, F. H. (T.L. Petit and G.O. Iwy eds.) Alan R. Liss, New York, pp. 171-199, (1987)
Hippocampal sharp waves: A physiological correlate of LTP?
Buzsáki, G. and Haas, H. L. In: Synaptic plasticity in the hippocampus. (H.L. Haas and G. Buzsáki eds.) Springer, Heidelberg, pp. 90-92 (1987)
Generation of hippocampal slow wave patterns.
Buzsáki, G. In: The Hippocampus. (R.L. Isaacson and K. Pribram eds.) vol. 3. Plenum Press, New York, pp. 137-167, (1986.)
Restoration of RSA (theta) in the denervated hippocampus by brain transplants.
Buzsáki, G., Gage, F. H. and Bjorklund, A. In: Learning and Memory: Mechanisms of Information Storage in the Nervous System. (H. Matthies ed.) Pergamon Press, Oxford, pp. 137-140, (1986)
Electroanatomy of the hippocampal rhythmic slow wave activity (RSA) in the behaving rat.
Buzsáki, G. In: Electrical Activity of the Archicortex. (G. Buzsáki and C. H. Vanderwolf eds.) Akademiai Kiado, Budapest, pp. 190-211, (1985)
What does the "LTP model" of memory, model? In: Brain Plasticity, Learning and Memory.
Buzsáki, G. (B. Will, P. Schmitt, J.C. Dalrymple-Alford, eds.) Plenum Press, New York, pp. 157-166, (1985).
Hippocampal slow waves: Sources of controversy. In: Neuronal Plasticity and Memory Formation
Buzsáki, G., Grastyan, E., Haubenreiser, J., Czopf, J. and Kellenyi, L. , (C. Ajmone Marsan and H. Matthies eds.) Raven Press, New York, pp. 511-529, (1982)
Why do we need a new theory of learning?
Buzsáki, G. In: Biologiai Tanulmanyok, (V. Csanyi, ed.) Akademiai Kiado, pp. 128-154, (1982) (in Hungarian)
The electrical correlates of the conditioned reflex in the cat.
Grastyan, E., Buzsáki, G., Molnar, P. and Lenard, L. In: Functional Significance of the Electric Processes of the Brain. Nauka Press, pp. 11-20, (1977) (in Russian)
Three different functional states reflected by two components of the hippocampal theta wave complex.
Grastyan, E., Molnar, P., Buzsáki, G. and Lenard, L. In: The Brain Mechanism, (T. N. Oniani ed.) Metsniereba Publishers, Tbilisi, USSR, pp. 288-295, (1975)
György Buzsáki (2007): The structure of consciousness. Nature 446:267 [PDF].
Buzsáki, G., Pare, D. (2006) Mircea Steriade (1924--2006). Nature Neuroscience 9:713
We Do, Therefore We Think: Time, Motility, and Consciousness.
Goodrich B. Reviews in the Neurosciences 21, 331-361 (2010)
[PDF]
The Brain Prize 2011: From Microcircuit Organization to Constellations of Brain Rhythms.
Soltesz I. Trends Neurosci. 2011 Oct;34(10):501-3. Epub 2011 Sep 13
[PDF]
Polyrhythms of the brain.
Battaglia FP, McNaughton BL. Neuron. 2011 Oct 6;72(1):6-8.
[PDF]
Distinct or Gradually Changing Spatial and Nonspatial Representations along the Dorsoventral Axis of the Hippocampus.
Yartsev M. J Neurophysiol 30(23):7758-7760, 2010.
[PDF]
Hippocampal Neural Assemblies and Conscious Remembering.
Shirvalkar PR. J Neurophysiol 101: 2197-2200, 2009.
[Full Text]
The Multiple Origins and Laminar Topography of the Hippocampal Theta Rhythm.
Shirvalkar PR, Bahar AS. J. Neurosci. 2009; 29: 7111-7113.
[PDF]
Brain is a hypercomplex space-time translator.
Oleg Senkov (2008). Scientific
America Russia.
[Full Text (Russian)]
[Full Text (English)]
Alzheimer Research Forum. (Commentary on Pastalkova et al. (2008), Science 5894:1322-7)
Tom Fagan (2008).
[Full Text]
Selected for Faculty of 1000 Biology (Commentary on Pastalkova et al. (2008), Science 5894:1322-7)
[Full Text after login]
Interview with Greg Miller(Commentary on Pastalkova et al. (2008), Science 5894:1322-7) .
Science Magazine(2008).
[MP3]
Learning and memory: Replay that track.(Commentary on Pastalkova et al. (2008), Science 5894:1322-7)
Leonie Welberg (2008). Nature Reviews
Neuroscience 9, 739. [PDF]
Hippocampal Firing Patterns Linked to Memory Recall.(Commentary on Pastalkova et al. (2008), Science 5894:1322-7)
Greg Miller (2008). Science 321
5894:1280-1281. [PDF]
Book review on Buzsáki, G. (2006): Rhythms of the Brain.
John G. Milton (2007). MathSciNet [PDF]
(Oxford University Press.)
Book review on Buzsáki, G. (2006): Rhythms of the Brain.
Dimitri M. Kullmann (2007). Neuron 55:694-695 [PDF]
(Oxford University Press.)
Book review on Buzsáki, G. (2006): Rhythms of the Brain.
Rodolfo.R. Llinás (2007). Neuroscience 149:726-727. [PDF]
( Oxford University Press.)
Book review on Buzsáki, G. (2006): Rhythms of the Brain.
John Lisman (2007). Nat Neurosc 10:395. [PDF]
(Oxford University Press.)
Book review on Buzsáki, G. (2006): Rhythms of the Brain.
Mayank Mehta (2007). Nature 446:27. [PDF].
(Oxford University Press.)
Dialogues between Cortex and Hippocampus: Who Talks to Whom?
Tononi G, Massimini M, Riedner BA.
Neuron. 52:748-9 2006
[PDF].
High times for memory: cannabis disrupts temporal coordination among hippocampal neurons.(Article on Robbe et al. (2006), Nat Neuroscience 9:1526-33)
Soltesz I, Staley K.
Nat Neurosci. 9:1461-3 2006
[PDF].
Several commentaries in the popular press.
on Robbe et al. (2006), Nat
Neuroscience 9:1526-33
The Powers of Rhythm.(Book review on Buzsáki, G. (2006): Rhythms of the Brain)
Fries, P. (2006): Science 314(5796):58-59
[PDF].
Oxford University Press.
Neurobiology: Interneurons take charge.
Moser, E.I. (2003): Nature 421:797-799
[PDF].
(News and Views article on Klausberger et al. (2003), Nature
[PDF].)
A prominent role for intrinsic neuron properties in temporal coding.
Magee, J.C. (2003): TINS 26:14-16 [PDF].
(Article on Harris et al. (2002), Nature [PDF].)
Windows on the brain.(News feature covering work in our lab.)
Chicurel, M. (2001): Nature 412: 266-268
[PDF].
The Cortical Discoverer Award: György Buzsáki.
Ribak, C.E. (2001): Krieg Cortical Kudos 2001: Cerebral Cortex 11:888-890
[PDF].
We about others:
Neuroscience: Neurons and navigation.(News and Views)
Buzsáki, G. (2005): Nature 436:781-2
[PDF].
Similar is different in hippocampal networks.(Perspectives)
Buzsáki, G. (2005): Science 309:568-9
[PDF].
Electrical wiring of the oscillating brain.(Preview)
Buzsáki, G. (2001): Neuron 31:342-344
[PDF].
Interconnected Stories of Brain Rhythms.(Book Review)
Buzsáki, G. (2001): Science 294:
2295-2297 [PDF].
Neuroscope |
| Developed by: Lynn Hazan lynn.hazan@myrealbox.com |
| NeuroScope can display local field potentials (EEG), neuronal spikes, behavioral events, as well as the position of the animal in the environment. It also features limited editing capabilities. |
Klusters |
| Developed by: Lynn Hazan lynn.hazan@myrealbox.com |
| Klusters is a powerful and easy-to-use cluster cutting application designed to help neurophysiologists sort action potentials from multiple neurons on groups of electrodes (e.g., tetrodes or multisite silicon probes). |
Klustakwik |
| Developed by: Kenneth D. Harris lynn.hazan@myrealbox.com |
| KlustaKwik is a program for automatic cluster analysis, specifically designed to run fast on large data sets. |
We will either find a way or we make one (Hannibal, 218 v. Chr)
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| We introduce a new head-fixed paradigm where all changing stimuli are controlled by the locomotion of the mouse. We demonstrate how division of labor between perisomatic (parvalbumin (PV) expressing) or dendrite-targeting (somatostatin (SOM) expressing) interneurons affect the rate, bursting and timing of pyramidal neurons, using optogenetic methods combined with large-scale silicon probe recordings of unit activity. |
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| Here we propose that mechanisms of memory and planning have evolved from mechanisms of navigation in the physical world and hypothesize that the neuronal algorithms underlying navigation in real and mental space are fundamentally the same. We review experimental data in support of this hypothesis and discuss how specific firing patterns and oscillatory dynamics in the entorhinal cortex and hippocampus can support both navigation and memory. |
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| This works assigns assign a prominent role of REM sleep in sleep-related neuronal plasticity by demonstrating how firing rates of hippocampal pyramidal cells and interneurons and their synchrony changes during the sleep cycle. |
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| Theta waves are phase shifted by 180o across cell layers, between CA1 and CA3 regions and from the septal to the temporal pole of the hippocampus. |
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| Spikes contribute to the higher frequency bands of the local field. This work quantified the contribution of spiking to ripple oscillations in the hippocampal CA1 region. |
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| Experimental setup for closed-loop feedback transcranial electrical stimulation (TES). Here, we demonstrate that seizure-triggered, feedback TES can dramatically reduce spike-and-wave episodes in a rodent model of generalized epilepsy. Closed-loop TES can be an effective clinical tool to reduce pathological brain patterns in drug-resistant patients. |
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| Neuronal activity in the brain gives rise to transmembrane currents that can be measured in the extracellular medium. We review here the major contributors of the extracellular signal, including the synaptic transmembrane current, Na(+) and Ca(2+) spikes, ionic fluxes through voltage- and ligand-gated channels, and intrinsic membrane oscillations and address the inverse problem of the local field potential. We also hypothesize that high-density LFP recordings can provide covert access to spiking cell assemblies. |
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| High frequency oscillations are ubiquitous in the brain under both physiological conditions and in disease. This review is part of the special issue dedicated to this important topic. The figure shows the emergence and spread of sharp wave ripples from the hippocampus to the entorhinal cortex. |
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| We describe here a diode-probe system that allows real-time and location-specific control of neuronal activity at multiple sites. Manipulation of neuronal activity in arbitrary spatiotemporal patterns is achieved by means of an optoelectronic array, manufactured by attaching multiple diode-fiber assemblies to high-density silicon probes or wire tetrodes, and implanted into the brains of animals that are expressing light-responsive opsins. The capacity of the system to generate synthetic neural activity patterns facilitates multi-site manipulation of neural circuits in a closed-loop manner in the behaving animal. |
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| Because of their ubiquitous nature and strong correlation with the “operational modes” of local circuits, gamma oscillations provide important clues about neuronal population dynamics in health and disease. Here, we review the cellular and synaptic mechanisms underlying gamma oscillations and outline empirical questions and controversial conceptual issues. |
|
| We introduce a new head-fixed paradigm where all changing stimuli are controlled by the locomotion of the mouse. We demonstrate how division of labor between perisomatic (parvalbumin (PV) expressing) or dendrite-targeting (somatostatin (SOM) expressing) interneurons affect the rate, bursting and timing of pyramidal neurons, using optogenetic methods combined with large-scale silicon probe recordings of unit activity. |
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| Here, we describe and illustrate our methods for recording multiple single neurons and local field potential in behaving rodent; fabrication of microdrives for chronic recordings with silicon probes and our surgical procedures. |
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| This paper is a 'catalog' of the various physiological, network and behavioral correlates of firing pattern differences and similarities between CA1 and CA3 pyramidal cells in the rat. The conclusions are based on >3,000 CA1 and >2,000 CA3 pyramidal neurons recorded over the years in our lab in various testing environments. |
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| 120 years ago Karoly Schaffer made the important discovery of demonstrating the associational connections between the inferior and superior regions (i.e., CA3 and CA1) of the hippocampus. We review the circumstances of the discovery and the impact it made on hippocampal research. |
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| How multiple frequencies in different structures interfere and/or reinforce each other to support behavior is a fascinating question. Here we show how a 4-Hz oscillation in the PFC-VTA axis interact with the hippocampal theta rhythm and how their joint effect can modulate gamma oscillations and unit firing in each of these structures. Such multi level cross-frequency coupling appears an effective mechanism to temporally coordinate neuronal activity in widespread brain areas. |
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| How multiple frequencies in different structures interfere and/or reinforce each other to support behavior is a fascinating question. Here we show how a 4-Hz oscillation in the PFC-VTA axis interact with the hippocampal theta rhythm and how their joint effect can modulate gamma oscillations and unit firing in each of these structures. Such multi level cross-frequency coupling appears an effective mechanism to temporally coordinate neuronal activity in widespread brain areas. |
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| Perhaps the most intensely investigated brain region in the brain is the hippocampal CA1 region. Part of the reasons for this popularity stems from the assumption that this region contains a homogeneous set of pyramidal cells. This work shows that there are at least two sublayers in the CA1 pyramidal layer with distinct biophysical and circuit properties of deep and superficial pyramidal cells. These two circuits can cooperate and segregate information in a brain state-dependent manner. The idea of two sublayers goes back to Schaffer (1882). |
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| Example trace of wide-band traces of ripple (left) and fast gamma (right) oscillation bursts from the CA1 stratum pyramidale (pyr) and radiatum (rad), CA3 pyramidal layer, and dentate granule cell layer (DG S. gran) in a sleeping rat, overlaid on their respective wavelet spectrograms. We examine the cellular, network properties of these respective patterns and show how neocortical-entorhinal inputs can affect their occurrence. |
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| Although glucose is the primary energetic substrate of the brain, it has been debated whether neurons directly metabolize glucose, or alternatively, glucose is broken down to lactate by astrocytes, which feed the neurons by lactate. We examined these hypotheses by examining the incorporation of a nonmetabolizable fluorescent glucose analog (green in the figure; astrocytes red), using 2-photon laser scanning microscopy in the rat S1 cortex in vivo. Whisker stimulation lead to a quick incorporation of the glucose analog in astrocytes but much less so in neurons. These results provide direct support for the glia-neuron "lactate-shuttle" hypothesis of Magistretti and Pellerin put forward 15 years ago. Progress takes time! |
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| While all neuroscientists agree that neurons in the brain come together temporally to form coalitions ('cell assemblies'), there is neither an accepted definition of such hypothetical neuronal assemblies nor a strategy how to identify them. This review suggests that assemblies make sense only from the viewpoint of a goal (referred to as an 'observer or reader' mechanism) and discusses potential experimental paradigms for a disciplined way to study them. |
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| Transcranial electrical stimulation (TES) can produce diffuse currents in the brain and lead to stimulus-locked firing in cortical neurons. The figure shows various configurations of the extracranial electrodes in rats, and the impact of sinusoid ~1 Hz TES on extracellular and intracellular activities. In addition as an experimental tool, TES is an ideal method for therapeutic control of brain activity. |
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| The entorhinal cortex is an important generator theta oscillations and gives rise to interesting dynamics, such as the 'grid' cells of the Mosers. This work provides critical anatomical data about the in vivo connectivity of layer 2, 3 and 5 neurons in the entorhinal cortex of the rat and shows that stellate cells are critical components of theta generation. NeuroLucida data of the reconstructed neurons are available upon request. |
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| This paper describes novel methods for delivering light to a very small volume of brain tissue using the combination of etched optic fibers with large scale recording of neurons by silicon probes in behaving rats and mice. These methods open new possibilities to perturb the local circuit in a controlled manner, activating or silencing only those neurons whose activity is constantly being monitored as well. This work was performed at my 'satellite' lab at Janelia Farm, in collaboration with Jeff Magee and his excellent people. |
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| Spikes of nearly all hippocampal place cells and episode cells oscillate faster than the oscillation frequency of the simultaneously recorded population (also reflected by the LFP theta; as shown by this figure). Our model shows why: the temporal delays between place cells (according to a ‘compression’ rule; i.e., distance representations are proportional to the within-theta spike time delays) shift the population frequency lower. The model accounts for all known major features of hippocampal place cells. |
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| While the hippocampus is a giant single module its inputs, outputs, local wiring and intrinsic properties of neurons differ along the septo-temporal axis. Recording from neurons in dorsal and ventralmost part of the hippocampus, we find numerous quantitative and qualitative differences between these populations. Theta rhythmicity was less pronounced in the ventral part, yet theta oscillations phase modulated gamma power at all locations. Thus, theta may bind together the results local computations into a more global pattern. |
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| How multiple frequencies in different structures interfere and/or reinforce each other to support behavior is a fascinating question. Here we show how a 4-Hz oscillation in the PFC-VTA axis interact with the hippocampal theta rhythm and how their joint effect can modulate gamma oscillations and unit firing in each of these structures. Such multi level cross-frequency coupling appears an effective mechanism to temporally coordinate neuronal activity in widespread brain areas. |
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| How multiple frequencies in different structures interfere and/or reinforce each other to support behavior is a fascinating question. Here we show how a 4-Hz oscillation in the PFC-VTA axis interact with the hippocampal theta rhythm and how their joint effect can modulate gamma oscillations and unit firing in each of these structures. Such multi level cross-frequency coupling appears an effective mechanism to temporally coordinate neuronal activity in widespread brain areas. |
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| It's been known for more than a century that sleep somehow is important for learning and memory. Sigmund Freud further suspected that what we learned during the day was 'rehearsed' by the brain during dreaming, allowing memories to form. But while much recent research has focused on the correlative links between the hippocampus and memory consolidation during sleep, the specific processes that cause long-term memories to form has not been identified. Because sharp wave ripples have been implicated as the key mechanism for transferring transient hippocampal traces for long-term storage in the neocortex (Buzsaki, 1989), we decided to kill all ripples during post-learning sleep. While specific and selective elimination hippocampal ripples did not affect the structure of sleep, it prevented the rats from efficiently learning a hippocampus-dependent maze task. Identification of a specific brain pattern responsible for strengthening learned information could facilitate applied research for more effective treatment of memory disorders. (This image was designed by MZ but NN chose an ugly cover instead of this). |
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| The macroscopic theta oscillation is a result of multiple cooperating theta dipoles. Each layer in each hippocampal region represents a theta current source and the cooperation of these dipoles varies as a function of behavior. Therefore, for the demonstration of a relationship between theta oscillations and behavior/neuronal activity, precise regional verification of the current sources is required. |
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| A long-standing conjecture in neuroscience is that aspects of cognition depend on the brain's ability to self-generate sequential neuronal activity. In this work we show that neurons in the hippocampus fire in sequences that predict which arm of the maze the rat would run next even if it went the wrong way. These sequences likely represent the brain's internal mechanism for planning on the basis of similar past experience. In a radical departure from viewing the hippocampus as a mapping device of the external world, our findings suggest that similar neuronal mechanisms can support recall from memory and the planning of action sequences. |
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| The picture illustrates oscillatory ocean waves, which give rise to surges of local water splashes on the peak of the wave, akin to how theta oscillation biases the occurrence of gamma oscillation splashes throughout the cortex at the peak of hippocampal theta oscillation. We demonstrate how hippocampal theta oscillations modulate neocortical unit activity and gamma rhythms in rats during exploration and REM sleep. This study suggests a mechanism by which hippocampal theta creates the temporal windows of opportunity within which the multiple local computation in local neocortical circuits (gamma oscillations) can be effectively transferred to the hippocampus. (photo: Pascale Quilichini) |
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| REM sleep is the most mysterious state of the brain. The brain loses its control over muscles of the body and the environmental inputs are ignored. During this self-isolated steady state short bursts of motor outputs occur. We report here that these phasic bursts of REM are characterized by enhanced throroughputs in hippocampal networks. One can only speculate that the compressed neuronal contents of the hippocampus during the phasic events may be responsible for generating dream content of REM. (Image: Flaming-June by FrederickLeighton, Ponce Museum of Art). |
| Representation of the world and internal states of the brain are usually thought to be expressed in the firing patterns of neurons. However, short-term synaptic dynamics are equally effective in temporally storing information but experimental exploration of this mechanism in the behaving animal has not been possible until recently. High density recordings from local circuits with silicon probes allows access to this important coding mechanism. This paper demonstrates how synaptic weights vary dynamically according to task demands. |
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| Functional MRI is the most important window for probing the human brain. However, the neuronal events correlated with the BOLD signal ('activation maps') are not well understood. Here we discuss why understanding the role of inhibition in brain activity is so critical for the interpretation of such a 'mean field' signal. This review is a synthesis of nearly 3 years of intense discussion among the three of us (GB, KK, MR) with different expertise and perspectives on the brain. I enjoyed our interactions a lot and would like to thank Kai and Marc for being so patient and emphatic teachers. Image: Interneurons are fueled mainly by mitochondrium-dependent (arrows) oxidate phosphorilation. |
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| Abstract depiction of forward and reverse place-cell sequences. Each column represents a window in time, with subthreshold and suprathreshold place-cell activity. Sequences sampled in the middle are played out in full, in forward at the beginning, and in reverse at the end. |
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| The function of hilar mossy cells has remained a mystery. The collection of papers in this volume attempt to address their role. |
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| Gamma power in the CA1 str. radiatum and gamma coherence between CA3 and CA1 regions is consistently highest in the central (choice) arm of a T maze. These findings suggest that recall preferentially engages the CA3-CA1 associational system. |
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| Single CA3 neurons innervate from one half to two thirds of the hippocampus and contact targets in a relatively random manner. The implication is that the CA3-CA1 system represent a single large network module (with the possible separation of the ventral tip). |
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| Single CA3 neurons innervate from one half to two thirds of the hippocampus and contact targets in a relatively random manner. The implication is that the CA3-CA1 system represent a single large network module (with the possible separation of the ventral tip). |
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| In this collaborative research with Peter Somogyi's group, we identified several types of long-range GABAergic interneurons. In a restrictive sense, the term "interneuron" does not really here apply since these cells have as extensive axon arbors as those of the pyramidal cells, spanning regions and various structures. These long-range interneurons may serve as "short cuts" for converting the locally organized interneurons into a "small world network" (Buzsaki et al., TINS 2004). The large caliber and strong myelination of the projection axon of the long-range interneurons, relative to those of pyramidal cells (Figure) allow for an especially fast communication between neuronal assemblies. |
| Hippocampal place cells are speed-controlled oscillators. They oscillate faster than the "baseline" field theta and produce an interference pattern ("phase precession" - O'Keefe and Recce, 1993). |
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| Large areas of the neocortex and paleocortex reboot their activity several thousand times every night. Each delta wave (or DOWN state) is followed by an organized sequence neuronal recruitment rather than a random pattern of activity. The UP-state initiator neurons may gain their critical role from either their intrinsic properties or by their stronger functional connectivity in the network(s) they are embedded., and, potentially, may reflect experience-dependent effects. The temporal precision of the recruited neurons along the sequence decreases according to a power law. |
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| Large areas of the neocortex and paleocortex reboot their activity several thousand times every night. Each delta wave (or DOWN state) is followed by a period of sustained activity at a frequency of 0.5-1.5 Hz (i.e., the slow oscillation of Steriade et al., 1993). Granule cells of the dentate gyrus are also 'enslaved' to the slow oscillation. Although the firing patterns of CA3 and CA1 region neurons are also biased temporally, the CA3 region can give rise to self-generated patterns also during the DOWN state. Thus, the dentate-CA3 interface is a major functional gate. |
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| The active ingredient in marijuana (tetrahydrocannabinoid or THC) and a synthetic cannabinoid agonist interfere with synchronized activity between neurons in the hippocampus of rats. We recorded from multiple neurons in the hippocampus of rats. Normally neurons in this region form groups that fire action potentials in the time windows of gamma and theta oscillations. But when CB1 agonist was administered, this synchrony was disrupted. The drug did not change the total number of action potentials produced, just their tendency to occur synchronously in these time windows. Animals with less synchronized neural activity under the drug performed less well in a hippocampus-dependent test of memory, suggesting that synchronized neural firing is essential for normal hippocampal function. |
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| Among the most remarkable features of a memory episode is the sequential ordering of composite events and the spatial-temporal relationships that bind them together into a unique episode. Similar to episodic learning of serial events, sequential activation of hippocampal place cells during rat movement on a track is believed to produce a representation that binds past, present, and future locations into a ��spatial episode. Dragoi and Buzsaki show that compressed spatial place cell sequences are represented for several theta cycles by the temporally coordinated activity of hippocampal cell assemblies, with the activity of CA3 preceding the activity of CA1 assemblies by one-half of a theta cycle. The results suggest a role for CA3 in binding CA1 temporal place cell sequences into single episodes. The context and implications of this study and related recent work on hippocampal place cell assemblies are discussed in a Minireview by Suzuki. |
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| Representation of information in the hippocampus occurs at multiple spatio-temoporal scale, symbolized here by the fractal nature of the hippocampus. Superimposed are one-second segments of field potentials from 96-sites recorded simultaneously in the dorsal hippocampus. The behavioral-physiological functions of theta oscillations have been debated over the past 70 years and the current views are summarized in this issue. |
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| Performance of real networks can be simulated by a very large number computational models with various architectures, algorithms and expected differential responses to perturbations. The real challenge then is to identify the right model. Various computational, single cell and slice models have been offered for "phase precession", a potential phase-coding method used by the hippocampus to identify spatio-temporal relationship of sequential events. In order to examine the contribution of the hippocampal networks in this process, we perturbed progression of phase-precession of single place neurons but "switching off" the hippocampus for ~ 100-200 msec and resetting the phase of global theta oscillation. Despite these manipulations, hippocampal activity reorganized instantaneously and phase procession continued. These findings suggest that the hippocampal information is updated by every theta cycle. A "biologically relevant" model of phase-coding should behave similarly. |
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| The importance of long-term synaptic plasticity as a cellular substrate for learning and memory is well established. By contrast, little is known about how learning and memory are regulated by voltage-gated ion channels that integrate this synaptic information. We investigated this question using mice with general or forebrain-restricted knockout of the HCN1 gene, which we find encodes a major component of the hyperpolarization-activated inward current (Ih) and is an important determinant of dendritic integration in hippocampal CA1 pyramidal cells. Surprisingly, deletion of HCN1 from forebrain neurons enhances hippocampal-dependent spatial learning and memory. Deletion of HCN1 augments the power of theta oscillation in the CA1 region and enhances long-term potentiation (LTP) at the distal cortical inputs to CA1 neurons, where HCN1 is most strongly expressed, but has little effect on synaptic integration or LTP at the more proximal Schaffer collateral inputs. We suggest that HCN1 channels constrain spatial learning and memory by regulating dendritic integration of distal synaptic inputs. |
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| The Local hemodynamics of the cerebral cortex is the basis of modern functional imaging techniques, such as fMRIand PET. Despite the importance of local regulation of the blood flow, capillary level quantification of cerebral blood flow has been limited by the spatial resolution of functional imaging techniques and the depth penetration of conventional optical microscopy. He we use two-photon laser scanning microscopic imaging technique to monitor basal capillary flux in mice as a function of neuronal activity. Our results show that local hyper-synchronized neural activity is associated with increased capillary perfusion in a volume that is significantly smaller than the currently available resolution of the fMRI signal. |
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| How do you know where your nose is? In a more general context, you may ask: how does the sensory representation of the cortex acquire its real-world 3-dimensional representation of the world? Our short answer is that the 3-dimensional geometric layout of the skeletal muscle system is responsible for training the somatosensory system during early development. This stage coincides with the first organized cortical pattern in the form of a spindle-shaped rhythm, fine turning of local connectivity and the emergence of long-range cortico-cortical and cortico-spinal axons. Stochastic, isolated muscle twitches, limb movements and whole body jerks, triggered by autonomous spinal cord circuits in the later stages of pregnancy (human) and first week of life (rat), serve as a supervised algorithm that decreases the infinite possibilities of sensory input combinations to the minimum that will be used in later life. The movement - reafferentation - prolonged cortical activation sequence is among the finest examples of self-organization in nature. |
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| Recording from statistically representative samples of identified neurons from several local areas while minimally interfering with the brain activity is a major goal in systems neuroscience. Many other methods are available for studying the brain but in the end all these indirect observations should be translated back into a common currency - the format of neuronal spike trains - to understand the brain's control of behavior. Wire "tetrodes" and silicon probes can 'hear' pyramial cells as far away as 140um lateral in the cell body. A cylinder with a radius of 140 um contains ~1,000 neurons in the rat cortex, which is the number of theoretically recordable cells by a single electrode. High-density silicon probes and novel mathematical methods in the future may allow us to record all neurons in this volume. |
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| If you have seen Luis Bravo's extravaganza �Forever Tango� you can picture the qualitative essence of synchrony through rhythm: coupling through time by weak links. Instead of brute force, subtle facial expressions, harmonic body movement, light touch and other invisible magic link the partners swing in perfect unison. In the brain, synchrony can also be brought about by force, e.g. by strong excitation through glutamate receptors. Alternatively, it can emerge by phase coupling of oscillatory ensembles through weak links, such as the sparse long-range connections between cortical areas. We speculate that oscillation-based synchrony is an essential part of the brain�s design that serves numerous useful functions. |
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| Separation of principal cells and GABAergic interneurons is of utmost importance for the interpretation of neuronal interactions in the cortex. The cover shows high-density recording of neurons in layer 5 of the somatosensory cortex, using 8-shank, 64-site two-dimensional silicon probes. From their short-term synaptic interaction, units could be identified as excitatory or inhibitory. Large-scale recordings of neuronal activity, determination of their physical location in the cortex and their classification into pyramidal and interneuron classes provide the necessary tools for local circuit analysis. From: Bartho P, Hirase H, Monconduit L, Zugaro M, Harris KD, and Buzsaki G. Characterization of neocortical principal cells and interneurons by network interactions and extracellular features. |
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| The The performance of the brain is constrained by wiring length and maintenance costs. The apparently inverse relationship between number of neurons in the various interneuron classes and the spatial extent of their axon tree suggests a mathematically definable organization, reminiscent of �small-world� or scale-free networks observed in other complex systems. The wiring economy-based classification of cortical inhibitory interneurons is supported by the distinct physiological patterns of class members in the intact brain. We hypothesize that the complex wiring of diverse interneuron classes represents an economic solution for supporting global synchrony and oscillations at multiple time scales with minimum axon length. Image: Detail from Mark Lombardi's now famous pencil drawing: Oliver North, Lake Resources of Panama, and the Iran-Contra Operation, 1984-86). Lombardi's artistic graphs capture the essence of small-world networks, a feature utilized by brain connectivity. |
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| Pericytes in the central nervous system (CNS) are hypothesized to be involved in important circulatory functions, including local blood flow regulation, angiogenesis, immune reaction, and regulation of blood-brain barrier. Despite these putative functions, functional correlates of pericytes in vivo are scarce. We have labeled CNS pericytes using the dextran-conjugated fluorescent calcium indicator Calcium Green I and imaged them in somatosensory cortex of the mouse in vivo. Intracellular calcium concentration in pericytes showed spontaneous surges lasting for several seconds. Furthermore, population bursts of neuronal activity were associated with increased Ca2+ signal in a portion of the pericytes. Selective in vivo labeling of pericytes with functional markers may help reveal their physiological function in neuronal activity-associated regulation of local cerebral blood flow. |
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| Large and long lasting cytosolic calcium surges in astrocytes have been described in cultured cells and acute slice preparations.The mechanisms that give rise to these calcium events have been extensively studied in vitro. However, their existence and functions in the intact brain are unknown. We have topically applied fluo-4 AM on the cerebral cortex of anesthetized rats and imaged cytosolic calcium fluctuation in astrocyte populations of superficial cortical layers in vivo, using 2-photon laser scanning microscopy. Spontaneous [Ca2+]i events in individual astrocytes were similar to those observed in vitro. Coordination of [Ca2+]i events among astrocytes was indicated by the broad cross-correlograms. Increased neuronal discharge was associated with increased astrocytic [Ca2+]i activity in individual cells and a robust coordination of [Ca2+]i signals in neighboring astrocytes. These findings provide indicate potential neuron-glia communication in the intact brain. |
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| This paper presents an eight-channel silicon neural probe with integrated CMOS circuitry designed for simultaneous recording and stimulation in the brain. The probe includes eight on-chip amplifiers that can be individually bypassed, allowing direct access to the iridium sites for electrical stimulation. The on-probe amplifiers have a gain of 38.9dB, an upper cutoff frequency of 9.9kHz, and an input referred noise of 9.2µVrms from 100Hz to 10kHz. The lowfrequency cutoff of the amplifier is tunable to allow the recording of field potentials and minimize stimulus artifact. The on-probe circuitry consumes 672µW from ±1.5V supplies and occupies 2.02mm2 in 3µm features. In-vivo recordings have shown that the preamplifiers can record single-unit activity 1ms after the onset of stimulation on sites as close as 20µm to the stimulating electrode. Further artifact suppression is achievable with precise tuning of the lowfrequency amplifier cutoff. |
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| Large-scale recording of neuronal activity in the hippocampus revealed assembly organization. Prediction of the timing of pyramidal cells spikes is improved using the spike times of peer neurons, over prediction from the animal�s trajectory in space, or a spatially-dependent theta phase modulation. Coordinated variability of spike timing in cell assemblies is assumed to represent a brain-derived (cognitive) process. |
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| Numerous things in nature follow the growth-rule of natural logarithm, e. Such an orderly relationship is also present between the various rhythms of the brain. The e relationship between network oscillations has numerous computational advantages as discussed in this paper. |
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| A short segment of wide band recording from layer V of the somatosensory cortex of the anesthetized rat during down-up-down state transition. 64-site recording with an 8-shank silicon probe. Recordings from separate shanks (8 recording sites each) are distinguished by alternating colors. Background shows detail of the preamplifier circuit integrated in the recording probe. |
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| The cover shows data obtained from two-dimensional recording of gamma oscillation in various hippocampal regions of the behaving rat. The six-shank silicon probe, with 16 recording sites each, is placed in the CA1-CA3 and dentate regions. The derived voltage traces are converted into currents to illustrate large amplitude and coherent gamma oscillatory activity in the CA3-CA1 pyramidal layer. A coronal section of the hippocampus stained with the Gallyas silver method (dark field photograph) is shown in the background. |
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| The physiological roles of neuronal gap junctions in the intact brain are not known. The recent generation of the connexin-36 knockout (Cx36 KO) mouse has offered a unique opportunity to examine this problem. Recent in vitro recordings in Cx36 KO mice suggested that Cx36 gap junction contributes to various oscillatory patterns in the theta (~5-10 Hz) and gamma (~30-80 Hz) frequency ranges, and affects certain aspects of high frequencies (>100 Hz) patterns. However, the relevance of these pharmacologically-induced patterns to the intact brain is not known. We recorded field potentials and unit activity in the CA1 stratum pyramidale of the hippocampus in behaving of wild type (WT) and Cx36 KO mice. Fast-field �ripple� oscillations (140-200 Hz) were present in both WT and KO mice and did not differ significantly in power, intraepisode frequency or probability of occurrence. Thus, fast-field oscillations may either not require electrical synapses or may be mediated by a hitherto unknown class of gap junctions. Theta oscillations, recorded during either wheel running or rapid eye movement sleep, were not different either. However, the power in the gamma frequency band and the magnitude of theta-phase modulation of gamma power were significantly decreased in KO mice compared to WT controls during wheel running. This suggests that Cx36 interneuronal gap junctions selectively contribute to gamma oscillations. |
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| Genetic engineering of the mouse brain allows investigators to address novel hypotheses in vivo. Because of the paucity of information on the network patterns of the mouse hippocampus, we investigated the electrical patterns in the behaving animal using multisite silicon probes and wire tetrodes. Theta (6�9 Hz) and gamma (40�100 Hz) oscillations were present during exploration and rapid eye movement sleep. Gamma power and theta power were comodulated and gamma power varied as a function of the theta cycle. Pyramidal cells and putative interneurons were phase-locked to theta oscillations. During immobility, consummatory behaviors and slow-wave sleep, sharp waves were present in cornu ammonis region CA1 of the hippocampus stratum radiatum associated with 140�200-Hz "ripples" in the pyramidal cell layer and population burst of CA1 neurons. In the hilus, large-amplitude "dentate spikes" occurred in association with increased discharge of hilar neurons. The amplitude of field patterns was larger in the mouse than in the rat, likely reflecting the higher neuron density in a smaller brain. We suggest that the main hippocampal network patterns are mediated by similar pathways and mechanisms in mouse and rat. |
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| Cerebral Cortex Buzsaki et al. Cover Picture: Artistic rendering of the relationship between single spikes (white) and spike bursts under physiological observations. The image imitates a music score generated by the spikes of hippocampal pyramidal neurons. Occurrence of bursts (colored patterns) in pyramidal neurons requires previous non-spiking periods. The temporal relationship between single spikes and bursts is hypothesized to regulate the efficacy of synaptic inputs to pyramidal neurons. |
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| Hippocampal pyramidal cell-interneuron spike transmission is reliable and responsible for place modulation of interneuron discharge. |
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