Pyramidal neurons

Anatomically segregated apical and basal dendrites of pyramidal neurons receive functionally distinct inputs, but it is unknown if this results in compartment-level functional diversity. Hippocampal place cells exhibit representational drift (Ziv et al., 2013), but this has only been characterized with somatic recordings. While dendritic activity is implicated in the formation of stable place fields and shaping hippocampal activity, in vivo studies of hippocampal dendritic activity have largely been confined to basal dendrites (Sheffield and Dombeck, 2015) or small cross-sections of apical den

Cortical circuits are built from diverse collections of neurons. Recent large-scale surveys have characterized this striking variability in terms of molecular, morphological, and electrophysiological features, identifying hundreds to thousands of distinct neuronal cell types. However, in computational neuroscience, we often stick our heads in the sand and ignore these details, instead basing theory on homogeneous populations of simple ‘point neurons'. The problem with this approach is that it's currently unknown what is lost with such simplifying assumptions. The simplification may be entirely

A pivotal challenge in computational neuroscience is identifying sub-populations of neurons that encode behavior, perception, and memory, across varying contexts such as task difficulty or temporal progression. Therefore, analysis tools that provide model interpretability, beyond prediction performance, are essential for studying neuronal population activity. We propose a novel approach conditional-STochastic Gates (c-STG) that combines predictive modeling with contextual feature selection. c-STG comprises two networks: a hypernetwork that maps contextual variables to probabilistic feature sel

…measured the synaptic strength between neurons in the Piriform cortex (PCx) following mice learning an odor discrimination task. Our results suggest that an assembly forms after learning, but

…by the distal apical dendrites of pyramidal neurons. These distal apical dendrites are long tree-like extensions which are electro- tonically segregated from the cell body under passive propagation of membrane potential. At the same time, incoming sensory inputs primarily target the region closest to the cell body. The relative coupling of activity between these neuronal regions (i.e. simultaneous v

…cell assemblies, groups of co-active neurons that represent a distinct cognitive unit, potentially related to specific behaviors or representations. Conventionally, cell assemblies are defined by strong structural connections, such that the stimulation of a portion of its members should transiently activate the entire assembly. Their exact composition and computational role, however, have yet to be fully clarified. We present the detection of spik

…error backpropagation (BP), where neurons adjust synapses to minimize a backpropagated error. The second approach, target learning (TL), proposes that neurons learn by reducing feedback needed to achieve desired activity patterns. While both theories are computati

The mammalian neocortex possesses the remarkable ability to translate complex sensory inputs into abstract representations through the coordinated activity of large neuronal ensembles across the sensory hierarchy. Theoretical works have proposed a variety of algorithms to coordinate learning across this hierarchy, including approximations of backpropagation of error as well as target-based methods such as predictive coding or control methods. In order to test the biological validity of these algorithms, we analyze the learning principles of the cortex, starting at the level of the synapse and

…from and how they are utilized within neurons remains obscure. For years, the neuroscientific community has known ab

During cortical development, GABAergic interneurons refine their connectivity in response to changes in activity of their postsynaptic targets, contributing to the establishment of functional neural circuits. Parvalbumin-expressing chandelier cells, a GABAergic interneuron subtype that forms axo-axonic synapses at the axon-initial segment (AIS) of pyramidal neurons, are optimally positioned to regulate network-wide spiking activity. It has been shown that chandelier cells change the number and density of their axon-targeting synapses onto L2/3 pyramidal neurons following chronic changes in net

Rebound depolarization (RD) is a form of membrane depolarization triggered in some neurons following hyperpolarization. Typically, a series of action potentials are evoked during RD plateau. RD converts an inhibitory signal arriving to the neuron into an excitation signal, which is subsequently synaptically transmitted to other cells. The nature of RD in cortical neurons has been tested for several years without satisfactory explanation. The aim of our study was to evaluate the influence of adrenergic receptors activation in RD generation. Alpha-1, alpha-2, and beta-receptors have been tested.

The mouse prefrontal cortex (PFC) is an umbrella term for rostrally located neocortical brain regions. The anterior cingulate, pre- and infralimbic, orbital, agranular insular and secondary motor cortices are generally included in the PFC. The PFC is critically involved in the acquisition and expression of flexible behavioral responses to changing sensory information, and prefrontal signalling to (neocortical) sensory regions is assumed to be essential to these processes.In the present study, we characterized the anatomical organization of excitatory, prefrontal projections to neocortical sens

Pyramidal neurons have prominent apical dendrites that are hypothesised to modulatesomatic output. In the visual cortex, apical dendrites may receive contextual signals via top-down inputs and local inhibition. It is not known, however, what causal effects they play indriving or suppressing somatic activity, and how they shape a neuron’s visual tuning.We recorded activity of pyramidal neurons sparsely expressing GCaMP7s in layer 5 of visualcortex in awake mice before and after pruning their apical dendrites with two-photondendrotomy. Together with the neuron’s receptive field and orientation/d

The ability to form associations is one of the fundamental features of the brain. Pavlov's original work on classical conditioning employed CS that immediately preceded reinforcement. Here, using the model of context preexposure (Rudy, O'Reilly, 2001; Vorobieva et al., 2017), we studied how an engram of a distant past context can become a CS. Mice explored a new context, and then with different delays (from 30 minutes up to 30 days) received an immediate shock in the same environment. We showed that contextual memory engram can be conditioned at all tested intervals. We then used c-Fos express

Astrocytes are active players in brain function. They sense and respond to neuronal activity by elevating intracellular calcium levels. These calcium elevations exhibit complex spatiotemporal patterns across the soma and main processes and focal microdomains. This activity underlies the astrocytic involvement in synaptic transmission, metabolism, and brain homeostasis. Here, we performed a multi-level analysis of the IP3 receptor type 2 knockout (IP3R2 KO) mouse model lacking global calcium elevations in astrocytes to disclose its implications to the molecular, cellular, and behavior levels. T

…a subpopulation of GABAergic interneurons. SST exerts its physiological role through 5 G protein-coupled receptors. This neuropeptide is of great interest in the pathophysiological context as a deficit of SST is observed in many neurological diseases, such as epilepsy. In the hippocampus, the effects of SST on the principal cells are known. It inhibits excitatory synaptic transmission by decreasing glutamate release from pyramidal neurons and reduces their intrinsic excitability by facilitating currents carried by Kv7 channels

Stressful behavior is transferred epigenetically. Here we study the biophysical mechanism of such epigenetic inheritance. Mice were exposed to varying protocols of tone-shock fear conditioning: a predictable group exposed to repetitions of consistent pairs of tone-shock; an unpredictable group exposed to tone and shocks in a random order; a naïve control [MOU1] group exposed to home cage conditions. After two weeks, all groups were exposed to the tone only for three days. The unpredictable group exhibited significantly higher freezing than both control and predictable groups on all three days,

Ventral pathway circuits are constituted by the interconnected brain areas that are distributed throughout the brain. They are primarily involved in processing of object related information in brain. However, their role in object recognition memory (ORM) enhancement remains unknown. In this study, we show that an activation of each of the brain areas interconnected to ventral pathway circuits individually induced enhancement in ORM; however, same treatment in brain areas not interconnected to ventral pathway circuits produced no effect. Further study in perirhinal cortex (PRh), area V2 of visu

Dendritic spines of pyramidal neurons are thin protrusions of the neuron membrane and represent the main postsynaptic sites in the cerebral cortex. Spines can have different morphologies: investigating their shape gives indications about the functional state of synapses during brain development. Quantifying dendritic spine shape changes will boost the comprehension of several neuropathies, such as Alzheimer and autism spectrum. Detection of dendritic spines is challenged by optical limitations. We propose a fully automated pipeline to segment and cluster spines to classify them according to th

…and increased neuronal activity in M1 pyramidal neurons. Both behavioral and neuronal phenotypes were rescued by chemogenetic activation of LC-NA. We next

Neurons in sensory areas are tuned to various input features, and tuning properties reveal essential aspects of the computation performed by the neuronal population. In the post-subiculum (PoSub), neurons are modulated by the animal’s head-direction (HD), and most pyramidal neurons are fine tuned to a specific direction. Other cell types, especially fast-spiking neurons, are less specifically tuned but are generally still modulated by HD. By recording from ensembles of neurons in the PoSub in freely moving mice with linear silicon probes, making it possible to determine precise anatomical loca

Micro-coils were designed to selectively activate pyramidal neurons (PNs), avoiding axonal stimulation, and potentially overcoming the limitations of conventional electric stimulation[1][2]. Finite element simulations showed a significant impact of micro-coil design on neuron activation selectivity[3]. A V-shaped bend at the micro-coil tip-enhanced field gradient selectivity vertically, leading to spatially confined cortical activation. In previous in vivo experiments, extracellular electrodes were necessary for recording neuronal action potentials, potentially increasing brain tissue damage[4

We often perceive memories as unified experiences although they comprise a multiplicity of different modalities and features. How the different aspects of a memory are encoded separately or jointly in the brain’s memory systems is not well understood. A key brain structure that has been identified to be involved in processing emotional memories is the ventral hippocampus. In our study we use virtual environments to induce in head-fixed mice the recall of distinct memories of a trace fear conditioning, consisting of a cue-triggered temporal and a context-triggered emotional component. To invest

…specific subcellular compartments of Pyramidal Neurons (PNs) such as dendrites, soma and axon initial segment (AIS) thus shaping the cellular computations underlying memory formation. Yet, very little is known about the long-term structural dynamics of these compartmentalized inhibitory synapses on PNs and their link to learning.To address these outstanding questions, we used longitudinal in viv