27 research outputs found
Application of a flexible polymer microECoG array to map functional coherence in schizophrenia model
Electrophysiological and behavioral properties of 4-aminopyridine-induced epileptic activity in mice
Network dynamics of encoding and retrieval of behavioural spike sequences during theta and ripples in a CA1 model of the hippocampus
Recall Performance Improvement in a Bio-Inspired Model of the Mammalian Hippocampus
Mammalian hippocampus is involved in short-term formation of declarative memories. We employed a
bio-inspired neural model of hippocampal CA1 region consisting of a zoo of excitatory and inhibitory
cells. Cellsâ firing was timed to a theta oscillation paced by two distinct neuronal populations exhibiting
highly regular bursting activity, one tightly coupled to the trough and the other to the peak of theta. To
systematically evaluate the modelâs recall performance against number of stored patterns, overlaps and
âactive cells per patternâ, its cells were driven by a non-specific excitatory input to their dendrites. This
excitatory input to model excitatory cells provided context and timing information for retrieval of
previously stored memory patterns. Inhibition to excitatory cellsâ dendrites acted as a non-specific global
threshold machine that removed spurious activity during recall. Out of the three models tested, âmodel 1â
recall quality was excellent across all conditions. âModel 2â recall was the worst. The number of âactive
cells per patternâ had a massive effect on network recall quality regardless of how many patterns were
stored in it. As âactive cells per patternâ decreased, networkâs memory capacity increased, interference
effects between stored patterns decreased, and recall quality improved. Key finding was that increased
firing rate of an inhibitory cell inhibiting a network of excitatory cells has a better success at removing
spurious activity at the network level and improving recall quality than increasing the synaptic strength of
the same inhibitory cell inhibiting the same network of excitatory cells, while keeping its firing rate fixed
In vitro and in vivo stability of black-platinum coatings on flexible, polymer microECoG arrays
Behavior-dependent activity patterns of GABAergic long-range projecting neurons in the rat hippocampus.
Longârange glutamatergic and GABAergic projections participate in temporal coordination of neuronal activity in distributed cortical areas. In the hippocampus, GABAergic neurons project to the medial septum and retrohippocampal areas. Many GABAergic projection cells express somatostatin (SOM+) and, together with locally terminating SOM+ bistratified and OâLM cells, contribute to dendritic inhibition of pyramidal cells. We tested the hypothesis that diversity in SOM+ cells reflects temporal specialization during behavior using extracellular single cell recording and juxtacellular neurobiotinâlabeling in freely moving rats. We have demonstrated that rare GABAergic projection neurons discharge rhythmically and are remarkably diverse. During sharp waveâripples, most projection cells, including a novel SOM+ GABAergic backâprojecting cell, increased their activity similar to bistratified cells, but unlike OâLM cells. During movement, most projection cells discharged along the descending slope of theta cycles, but some fired at the trough jointly with bistratified and OâLM cells. The specialization of hippocampal SOM+ projection neurons complements the action of local interneurons in differentially phasing inputs from the CA3 area to CA1 pyramidal cell dendrites during sleep and wakefulness. Our observations suggest that GABAergic projection cells mediate the behaviorâ and network stateâdependent binding of neuronal assemblies amongst functionallyârelated brain regions by transmitting local rhythmic entrainment of neurons in CA1 to neuronal populations in other areas
Behavior-dependent activity patterns of GABAergic long-range projecting neurons in the rat hippocampus.
Longârange glutamatergic and GABAergic projections participate in temporal coordination of neuronal activity in distributed cortical areas. In the hippocampus, GABAergic neurons project to the medial septum and retrohippocampal areas. Many GABAergic projection cells express somatostatin (SOM+) and, together with locally terminating SOM+ bistratified and OâLM cells, contribute to dendritic inhibition of pyramidal cells. We tested the hypothesis that diversity in SOM+ cells reflects temporal specialization during behavior using extracellular single cell recording and juxtacellular neurobiotinâlabeling in freely moving rats. We have demonstrated that rare GABAergic projection neurons discharge rhythmically and are remarkably diverse. During sharp waveâripples, most projection cells, including a novel SOM+ GABAergic backâprojecting cell, increased their activity similar to bistratified cells, but unlike OâLM cells. During movement, most projection cells discharged along the descending slope of theta cycles, but some fired at the trough jointly with bistratified and OâLM cells. The specialization of hippocampal SOM+ projection neurons complements the action of local interneurons in differentially phasing inputs from the CA3 area to CA1 pyramidal cell dendrites during sleep and wakefulness. Our observations suggest that GABAergic projection cells mediate the behaviorâ and network stateâdependent binding of neuronal assemblies amongst functionallyârelated brain regions by transmitting local rhythmic entrainment of neurons in CA1 to neuronal populations in other areas
Behavior-dependent specialization of identified hippocampal interneurons.
A large variety of GABAergic interneurons control information processing in the hippocampal circuits governing the formation of neuronal representations. Whether distinct hippocampal interneuron types contribute differentially to information processing during behavior is not known. We employed a new technique for recording and labeling interneurons and pyramidal cells in drug-free, freely moving rats. Recorded parvalbumin-expressing basket interneurons innervated somata and proximal pyramidal cell dendrites, whereas nitric oxide synthase- and neuropeptide Y-expressing ivy cells provided synaptic and extrasynaptic dendritic modulation. Basket and ivy cells showed distinct spike-timing dynamics, firing at different rates and times during theta and ripple oscillations. Basket, but not ivy, cells changed their firing rates during movement, sleep and quiet wakefulness, suggesting that basket cells coordinate cell assemblies in a behavioral state-contingent manner, whereas persistently firing ivy cells might control network excitability and homeostasis. Different interneuron types provide GABA to specific subcellular domains at defined times and rates, thereby differentially controlling network activity during behavior
Behavior-dependent specialization of identified hippocampal interneurons.
A large variety of GABAergic interneurons control information processing in the hippocampal circuits governing the formation of neuronal representations. Whether distinct hippocampal interneuron types contribute differentially to information processing during behavior is not known. We employed a new technique for recording and labeling interneurons and pyramidal cells in drug-free, freely moving rats. Recorded parvalbumin-expressing basket interneurons innervated somata and proximal pyramidal cell dendrites, whereas nitric oxide synthase- and neuropeptide Y-expressing ivy cells provided synaptic and extrasynaptic dendritic modulation. Basket and ivy cells showed distinct spike-timing dynamics, firing at different rates and times during theta and ripple oscillations. Basket, but not ivy, cells changed their firing rates during movement, sleep and quiet wakefulness, suggesting that basket cells coordinate cell assemblies in a behavioral state-contingent manner, whereas persistently firing ivy cells might control network excitability and homeostasis. Different interneuron types provide GABA to specific subcellular domains at defined times and rates, thereby differentially controlling network activity during behavior