@article {6490, title = {Activity dynamics and behavioral correlates of CA3 and CA1 hippocampal pyramidal neurons.}, journal = {Hippocampus}, volume = {22}, year = {2012}, month = {2012 Aug}, pages = {1659-80}, abstract = {

The CA3 and CA1 pyramidal neurons are the major principal cell types of the hippocampus proper. The strongly recurrent collateral system of CA3 cells and the largely parallel-organized CA1 neurons suggest that these regions perform distinct computations. However, a comprehensive comparison between CA1 and CA3 pyramidal cells in terms of firing properties, network dynamics, and behavioral correlations is sparse in the intact animal. We performed large-scale recordings in the dorsal hippocampus of rats to quantify the similarities and differences between CA1 (n \> 3,600) and CA3 (n \> 2,200) pyramidal cells during sleep and exploration in multiple environments. CA1 and CA3 neurons differed significantly in firing rates, spike burst propensity, spike entrainment by the theta rhythm, and other aspects of spiking dynamics in a brain state-dependent manner. A smaller proportion of CA3 than CA1 cells displayed prominent place fields, but place fields of CA3 neurons were more compact, more stable, and carried more spatial information per spike than those of CA1 pyramidal cells. Several other features of the two cell types were specific to the testing environment. CA3 neurons showed less pronounced phase precession and a weaker position versus spike-phase relationship than CA1 cells. Our findings suggest that these distinct activity dynamics of CA1 and CA3 pyramidal cells support their distinct computational roles.

}, keywords = {Action Potentials, Animal, Animals, Behavior, CA1 Region, CA3 Region, Electroencephalography, Hippocampal, Long-Evans, Male, Maze Learning, Nonparametric, Pyramidal Cells, Rats, Statistics, Theta Rhythm}, issn = {1098-1063}, doi = {10.1002/hipo.22002}, author = {Mizuseki, Kenji and Royer, S{\'e}bastien and Diba, Kamran and Buzs{\'a}ki, Gy{\"o}rgy} } @article {5924, title = {Control of timing, rate and bursts of hippocampal place cells by dendritic and somatic inhibition.}, journal = {Nature neuroscience}, volume = {15}, year = {2012}, month = {2012 May}, pages = {769-75}, abstract = {A consortium of inhibitory neurons control the firing patterns of pyramidal cells, but their specific roles in the behaving animal are largely unknown. We performed simultaneous physiological recordings and optogenetic silencing of either perisomatic (parvalbumin (PV) expressing) or dendrite-targeting (somatostatin (SOM) expressing) interneurons in hippocampal area CA1 of head-fixed mice actively moving a treadmill belt rich with visual-tactile stimuli. Silencing of either PV or SOM interneurons increased the firing rates of pyramidal cells selectively in their place fields, with PV and SOM interneurons having their largest effect during the rising and decaying parts of the place field, respectively. SOM interneuron silencing powerfully increased burst firing without altering the theta phase of spikes. In contrast, PV interneuron silencing had no effect on burst firing, but instead shifted the spikes{\textquoteright} theta phase toward the trough of theta. These findings indicate that perisomatic and dendritic inhibition have distinct roles in controlling the rate, burst and timing of hippocampal pyramidal cells.}, keywords = {Action Potentials, Animal, Animals, Behavior, Biophysics, Dendrites, Electric Stimulation, Exercise Test, Green Fluorescent Proteins, Halorhodopsins, Hippocampus, Humans, Inbred C57BL, Light, Mice, Movement, Neural Inhibition, Neurons, Optics and Photonics, Parvalbumins, Patch-Clamp Techniques, Photic Stimulation, Probability, Somatostatin, Spectrum Analysis, Time Factors, Time Perception, Touch, Transgenic}, issn = {1546-1726}, doi = {10.1038/nn.3077}, author = {Royer, S{\'e}bastien and Zemelman, Boris V and Losonczy, Attila and Kim, Jinhyun and Chance, Frances and Magee, Jeffrey C and Buzs{\'a}ki, Gy{\"o}rgy} } @article {4294, title = {Distinct representations and theta dynamics in dorsal and ventral hippocampus.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {30}, year = {2010}, month = {2010 Feb 3}, pages = {1777-87}, abstract = {

Although anatomical, lesion, and imaging studies of the hippocampus indicate qualitatively different information processing along its septo-temporal axis, physiological mechanisms supporting such distinction are missing. We found fundamental differences between the dorsal (dCA3) and the ventral-most parts (vCA3) of the hippocampus in both environmental representation and temporal dynamics. Discrete place fields of dCA3 neurons evenly covered all parts of the testing environments. In contrast, vCA3 neurons (1) rarely showed continuous two-dimensional place fields, (2) differentiated open and closed arms of a radial maze, and (3) discharged similar firing patterns with respect to the goals, both on multiple arms of a radial maze and during opposite journeys in a zigzag maze. In addition, theta power and the fraction of theta-rhythmic neurons were substantially reduced in the ventral compared with dorsal hippocampus. We hypothesize that the spatial representation in the septo-temporal axis of the hippocampus is progressively decreased. This change is paralleled with a reduction of theta rhythm and an increased representation of nonspatial information.

}, keywords = {Animals, Hippocampus, Long-Evans, Male, Maze Learning, Neurons, Rats, Space Perception, Theta Rhythm}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.4681-09.2010}, author = {Royer, S{\'e}bastien and Sirota, Anton and Patel, Jagdish and Buzs{\'a}ki, Gy{\"o}rgy} } @article {2121, title = {Multi-array silicon probes with integrated optical fibers: light-assisted perturbation and recording of local neural circuits in the behaving animal.}, journal = {The European Journal of Neuroscience}, volume = {31}, year = {2010}, month = {2010 Jun}, pages = {2279-91}, abstract = {

Recordings of large neuronal ensembles and neural stimulation of high spatial and temporal precision are important requisites for studying the real-time dynamics of neural networks. Multiple-shank silicon probes enable large-scale monitoring of individual neurons. Optical stimulation of genetically targeted neurons expressing light-sensitive channels or other fast (milliseconds) actuators offers the means for controlled perturbation of local circuits. Here we describe a method to equip the shanks of silicon probes with micron-scale light guides for allowing the simultaneous use of the two approaches. We then show illustrative examples of how these compact hybrid electrodes can be used in probing local circuits in behaving rats and mice. A key advantage of these devices is the enhanced spatial precision of stimulation that is achieved by delivering light close to the recording sites of the probe. When paired with the expression of light-sensitive actuators within genetically specified neuronal populations, these devices allow the relatively straightforward and interpretable manipulation of network activity.

}, keywords = {Action Potentials, Animal, Animals, Behavior, Electric Stimulation, Electrophysiology, Light, Mice, Neurons, Neuropsychological Tests, Optical Fibers, Photic Stimulation, Rats, Recombinant Fusion Proteins, Silicon}, issn = {1460-9568}, doi = {10.1002/cbic.201000254}, author = {Royer, S{\'e}bastien and Zemelman, Boris V and Barbic, Mladen and Losonczy, Attila and Buzs{\'a}ki, Gy{\"o}rgy and Magee, Jeffrey C} } @article {2342, title = {Temporal delays among place cells determine the frequency of population theta oscillations in the hippocampus.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {107}, year = {2010}, month = {2010 Apr 27}, pages = {7957-62}, abstract = {

Driven either by external landmarks or by internal dynamics, hippocampal neurons form sequences of cell assemblies. The coordinated firing of these active cells is organized by the prominent "theta" oscillations in the local field potential (LFP): place cells discharge at progressively earlier theta phases as the rat crosses the respective place field ("phase precession"). The faster oscillation frequency of active neurons and the slower theta LFP, underlying phase precession, creates a paradox. How can faster oscillating neurons comprise a slower population oscillation, as reflected by the LFP? We built a mathematical model that allowed us to calculate the population activity analytically from experimentally derived parameters of the single neuron oscillation frequency, firing field size (duration), and the relationship between within-theta delays of place cell pairs and their distance representations ("compression"). The appropriate combination of these parameters generated a constant frequency population rhythm along the septo-temporal axis of the hippocampus, while allowing individual neurons to vary their oscillation frequency and field size. Our results suggest that the faster-than-theta oscillations of pyramidal cells are inherent and that phase precession is a result of the coordinated activity of temporally shifted cell assemblies, relative to the population activity, reflected by the LFP.

}, keywords = {Action Potentials, Animals, Hippocampus, Locomotion, Models, Neurological, Pyramidal Cells, Rats, Theta Rhythm}, issn = {1091-6490}, doi = {10.1523/JNEUROSCI.3773-10.2011}, author = {Geisler, Caroline and Diba, Kamran and Pastalkova, Eva and Mizuseki, Kenji and Royer, S{\'e}bastien and Buzs{\'a}ki, Gy{\"o}rgy} }