scholarly journals Activity in the Barrel Cortex During Active Behavior and Sleep

2010 ◽  
Vol 103 (4) ◽  
pp. 2074-2084 ◽  
Author(s):  
Sujith Vijayan ◽  
Greg J. Hale ◽  
Christopher I. Moore ◽  
Emery N. Brown ◽  
Matthew Wilson
Keyword(s):  
Barrel Cortex ◽  
Slow Wave Sleep ◽  
Neural Firing ◽  
Related Activity ◽  
Firing Rates ◽  
Coding Schemes ◽  
Baseline Activity ◽  
Sensory Cue ◽  
The Individual

The rate at which neurons fire has wide-reaching implications for the coding schemes used by neural systems. Despite the extensive use of the barrel cortex as a model system, relatively few studies have examined the rate of sensory activity in single neurons in freely moving animals. We examined the activity of barrel cortex neurons in behaving animals during sensory cue interaction, during non–stimulus-related activity, during various states of sleep, and during the administration of isoflurane. The activity of regular-spiking units (RSUs: predominantly excitatory neurons) and fast spiking units (FSUs: a subtype of inhibitory interneurons) was examined separately. We characterized activity by calculating neural firing rates, because several reports have emphasized the low firing rates in this system, reporting that both baseline activity and stimulus evoked activity is <1 Hz. We report that, during sensory cue interaction or non–stimulus-related activity, the majority of RSUs in rat barrel cortex fired at rates significantly >1 Hz, with 27.4% showing rates above 10 Hz during cue interaction. Even during slow wave sleep, which had the lowest mean and median firing rates of any nonanesthetized state observed, 80.0% of RSUs fired above 1 Hz. During all of the nonanesthetized states observed 100% of the FSUs fired well above 1 Hz. When rats were administered isoflurane and at a depth of anesthesia used in standard in vivo electrophysiological preparations, all of the RSUs fired below 1 Hz. We also found that >80% of RSUs either upmodulated or downmodulated their firing during cue interaction. These data suggest that low firing rates do not typify the output of the barrel cortex during awake activity and during sleep and indicate that sensory coding at both the individual and population levels may be nonsparse.

Statistical Significance of Coincident Spikes: Count-Based Versus Rate-Based Statistics

2002 ◽  
Vol 14 (1) ◽  
pp. 121-153 ◽  
Author(s):  
Robert Gütig ◽  
Ad Aertsen ◽  
Stefan Rotter
Keyword(s):  
Neural Coding ◽  
Time Course ◽  
Statistical Significance ◽  
Event Analysis ◽  
Neural Firing ◽  
Test Power ◽  
Firing Rates ◽  
Coding Schemes ◽  
Significance Levels ◽  
Power Curves

Inspired by different conceptualizations of temporal neural coding schemes, there has been recent interest in the search for signs of precisely synchronized neural activity in the cortex. One method developed for this task is unitary-event analysis. This method tests multiple single-neuron recordings for short epochs with significantly more coincident spikes than expected from independent neurons. We reformulated the statistical test underlying this method using a coincidence count distribution based on empirical spike counts rather than on estimated spike probabilities. In the case of two neurons, the requirement of stationary firing rates, originally imposed on both neurons, can be relaxed; only the rate of one neuron needs to be stationary, while the other may follow an arbitrary time course. By analytical calculations of the test power curves of the original and the revised method, we demonstrate that the test power can be increased by a factor of two or more in physiologically realistic regimes. In addition, we analyze the effective significance levels of both methods for neural firing rates ranging between 0.2 Hz and 30 Hz.

scholarly journals State-dependent modulation of activity in distinct layer 6 corticothalamic neurons in barrel cortex of awake mice

2021 ◽  
Author(s):  
Suryadeep Dash ◽  
Dawn M Autio ◽  
Shane R Crandall
Keyword(s):  
Cortical Neurons ◽  
Barrel Cortex ◽  
Related Activity ◽  
Functional Roles ◽  
Firing Rates ◽  
State Dependent ◽  
Rich Diversity ◽  
Response Profiles ◽  
Strategic Position ◽  
Activity Dependent

Layer 6 corticothalamic (L6 CT) neurons are in a strategic position to control sensory input to the neocortex, yet we understand very little about their functions. Apart from studying their anatomical, physiological and synaptic properties, most recent efforts have focused on the activity-dependent influences CT cells can exert on thalamic and cortical neurons through causal optogenetic manipulations. However, few studies have attempted to study them during behavior. In an attempt to address this gap, we performed juxtacellular recordings from optogenetically identified CT neurons in whisker-related primary somatosensory cortex (wS1) of awake, head-fixed mice (of either sex) free to rest quietly or self-initiate bouts of whisking and locomotion. We found a rich diversity of response profiles exhibited by CT cells. Broadly, their spiking patterns were either modulated by whisker-related behavior (~28%) or not (~72%). Whisker-related neurons exhibited both increases as well as decreases in firing rates. We also encountered cells with preceding modulations in firing rate before whisking onset. Overall, whisking better explained these changes in rates than overall changes in arousal. The CT cells that showed no whisker-related activity had low spontaneous firing rates (<0.5 Hz), with many all but silent. Remarkably, this relatively silent population preferentially spiked at the state transition point when pupil diameter constricted and the mouse entered quiet wakefulness. Thus, our results demonstrate that L6 CT neurons in wS1 show diverse spiking patterns, perhaps subserving distinct functional roles related to precisely timed responses during complex behaviors and transitions between discrete waking states.

scholarly journals Distinct roles of parvalbumin and somatostatin interneurons in the synchronization of spike-times in the neocortex

2019 ◽  
Author(s):  
Hyun Jae Jang ◽  
Hyowon Chung ◽  
James M. Rowland ◽  
Blake A. Richards ◽  
Michael M. Kohl ◽  
...  
Keyword(s):  
Barrel Cortex ◽  
Feedback Inhibition ◽  
Spike Timing ◽  
Timing Synchronization ◽  
Inhibitory Interneurons ◽  
Sensory Stimuli ◽  
Firing Rates ◽  
Single Unit Recordings ◽  
Spatio Temporal

AbstractSynchronization of precise spike-times across multiple neurons carries information about sensory stimuli. Inhibitory interneurons are suggested to promote this synchronization, but it is unclear whether distinct interneuron subtypes provide different contributions. To test this, we examined single-unit recordings from barrel cortex in vivo and used optogenetics to determine the contribution of two classes of inhibitory interneurons: parvalbumin (PV)- and somatostatin (SST)-positive interneurons to spike-timing synchronization across cortical layers. We found that PV interneurons preferentially promote the synchronization of spike-times when instantaneous firing-rates are low (<12 Hz), whereas SST interneurons preferentially promote the synchronization of spike-times when instantaneous firing-rates are high (>12 Hz). Furthermore, using a computational model, we demonstrate that these effects can be explained by PV and SST interneurons having preferential contribution to feedforward and feedback inhibition, respectively. Our findings demonstrate that distinct subtypes of inhibitory interneurons have frequency-selective roles in spatio-temporal synchronization of precise spike-times.

Integration of Synaptic Responses to Neighboring Whiskers in Rat Barrel Cortex In Vivo

2005 ◽  
Vol 93 (4) ◽  
pp. 1920-1934 ◽  
Author(s):  
Michael J. Higley ◽  
Diego Contreras
Keyword(s):  
Barrel Cortex ◽  
Single Cells ◽  
Receptive Fields ◽  
Synaptic Integration ◽  
Synaptic Response ◽  
Cortical Function ◽  
Sensory Stimuli ◽  
Paired Stimulation ◽  
The Individual

Characterizing input integration at the single-cell level is a critical step to understanding cortical function, particularly when sensory stimuli are represented over wide cortical areas and single cells exhibit large receptive fields. To study synaptic integration of sensory inputs, we made intracellular recordings from the barrel cortex of anesthetized rats in vivo. For each cell, we deflected the principal whisker (PW) either alone or preceded by the deflection of a single adjacent whisker (AW) at an interval of 20 or 3 ms. At the 20-ms interval in all cases, prior AW deflection significantly suppressed the PW-evoked spike output and caused the underlying synaptic response to reach a peak Vm less depolarized than that arising from PW deflection alone. The decrease in peak Vm was not attributed to hyperpolarizing inhibition but to a divisive reduction in PW-evoked PSP amplitude. The reduction in amplitude was not a result of shunting inhibition but was mostly a result of removal of the synaptic drive, or disfacilitation. When the AW–PW interval was shortened to 3 ms, spike suppression was observed in a subset of the cells studied. In most cases, a divisive reduction in synaptic response amplitude was offset by summation with the preceding AW-evoked depolarization. To determine whether suppression is a general feature of synaptic integration by barrel cortex neurons, we also characterized the interaction of responses evoked by local electrical stimulation. In contrast to the whisker data, we found that responses to paired stimulation at the same intervals produced more spikes and reached a peak Vm more depolarized than the individual responses alone, suggesting that whisker-evoked suppression is not a result of postsynaptic mechanisms. Instead, we propose that cross-whisker response suppression depends on sensory-specific mechanisms at cortical and subcortical levels.

Crossmodal stimulation influences communication in visual-somatosensory cortical networks of the Brown Norway rat

2012 ◽  
Vol 25 (0) ◽  
pp. 92
Author(s):  
Kay Sieben ◽  
Ileana Hanganu-Opatz
Keyword(s):  
Barrel Cortex ◽  
Visual Stimulation ◽  
Multisensory Processing ◽  
Oscillatory Activity ◽  
Brown Norway ◽  
Norway Rat ◽  
Baseline Activity ◽  
Sensory Cortices ◽  
Oscillatory Coupling

Processing of most action goals and complete perception of the environment, like spatial localization of events, require integration of information from different sensory systems. The classical idea of a hierarchical sensory organization is challenged by recent evidence from both human and primate work showing that multisensory processing is already taking place in primary sensory cortices. However, the mechanisms underlying this multisensory processing and the role of primary sensory cortices in crossmodal communication and oscillatory coupling remain largely unknown. Congruent and incongruent uni- and bimodal visual (light spot) and tactile (whisker deflection) stimulation was performed simultaneously with extracellular multielectrode recordings in the primary visual (V1) and somatosensory (S1, barrel field) neocortices of adolescent Brown Norway rats in vivo. Tactile stimulation led after 10–30 ms to a phase-locked, large amplitude response in the contralateral S1 that is accompanied by prominent, layer-specific sinks and sources. Additionally, non-phase-locked oscillations were induced in different frequency ranges. Visual stimulation alone did not change the amplitude of oscillations compared to baseline activity in the contralateral S1, but reset the phase of ongoing oscillatory activity. Because of the visual impact in the S1, bimodal congruent stimulation led to an increase of the evoked response and changed the timing of amplitude enhancement of oscillations. These data indicate that networks in the barrel cortex are modulated by crossmodal visual input.

scholarly journals Distinct roles of parvalbumin and somatostatin interneurons in gating the synchronization of spike times in the neocortex

2020 ◽  
Vol 6 (17) ◽  
pp. eaay5333 ◽  
Author(s):  
Hyun Jae Jang ◽  
Hyowon Chung ◽  
James M. Rowland ◽  
Blake A. Richards ◽  
Michael M. Kohl ◽  
...  
Keyword(s):  
Computational Model ◽  
Single Unit ◽  
Barrel Cortex ◽  
Feedback Inhibition ◽  
Inhibitory Interneurons ◽  
Cortical Layers ◽  
Sensory Stimuli ◽  
Firing Rates ◽  
Single Unit Recordings

Synchronization of precise spike times across multiple neurons carries information about sensory stimuli. Inhibitory interneurons are suggested to promote this synchronization, but it is unclear whether distinct interneuron subtypes provide different contributions. To test this, we examined single-unit recordings from barrel cortex in vivo and used optogenetics to determine the contribution of parvalbumin (PV)– and somatostatin (SST)–positive interneurons to the synchronization of spike times across cortical layers. We found that PV interneurons preferentially promote the synchronization of spike times when instantaneous firing rates are low (<12 Hz), whereas SST interneurons preferentially promote the synchronization of spike times when instantaneous firing rates are high (>12 Hz). Furthermore, using a computational model, we demonstrate that these effects can be explained by PV and SST interneurons having preferential contributions to feedforward and feedback inhibition, respectively. Our findings demonstrate that distinct subtypes of inhibitory interneurons have frequency-selective roles in the spatiotemporal synchronization of precise spike times.

scholarly journals A deep convolutional visual encoding model of neuronal responses in the LGN

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Eslam Mounier ◽  
Bassem Abdullah ◽  
Hani Mahdi ◽  
Seif Eldawlatly
Keyword(s):  
Firing Rate ◽  
Visual Information ◽  
Visual Stimulation ◽  
Neuronal Population ◽  
Neuronal Firing ◽  
Electrode Arrays ◽  
Deep Convolutional Neural Networks ◽  
Firing Rates ◽  
Spatiotemporal Representation

AbstractThe Lateral Geniculate Nucleus (LGN) represents one of the major processing sites along the visual pathway. Despite its crucial role in processing visual information and its utility as one target for recently developed visual prostheses, it is much less studied compared to the retina and the visual cortex. In this paper, we introduce a deep learning encoder to predict LGN neuronal firing in response to different visual stimulation patterns. The encoder comprises a deep Convolutional Neural Network (CNN) that incorporates visual stimulus spatiotemporal representation in addition to LGN neuronal firing history to predict the response of LGN neurons. Extracellular activity was recorded in vivo using multi-electrode arrays from single units in the LGN in 12 anesthetized rats with a total neuronal population of 150 units. Neural activity was recorded in response to single-pixel, checkerboard and geometrical shapes visual stimulation patterns. Extracted firing rates and the corresponding stimulation patterns were used to train the model. The performance of the model was assessed using different testing data sets and different firing rate windows. An overall mean correlation coefficient between the actual and the predicted firing rates of 0.57 and 0.7 was achieved for the 10 ms and the 50 ms firing rate windows, respectively. Results demonstrate that the model is robust to variability in the spatiotemporal properties of the recorded neurons outperforming other examined models including the state-of-the-art Generalized Linear Model (GLM). The results indicate the potential of deep convolutional neural networks as viable models of LGN firing.

scholarly journals Preclinical Testing of Radiopharmaceuticals for the Detection and Characterization of Osteomyelitis: Experiences from a Porcine Model

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4221
Author(s):  
Aage Kristian Olsen Alstrup ◽  
Svend Borup Jensen ◽  
Ole Lerberg Nielsen ◽  
Lars Jødal ◽  
Pia Afzelius
Keyword(s):  
Animal Model ◽  
Animal Models ◽  
Porcine Model ◽  
Animal Experiments ◽  
Radioactive Tracers ◽  
The Individual ◽  
Selection Of

The development of new and better radioactive tracers capable of detecting and characterizing osteomyelitis is an ongoing process, mainly because available tracers lack selectivity towards osteomyelitis. An integrated part of developing new tracers is the performance of in vivo tests using appropriate animal models. The available animal models for osteomyelitis are also far from ideal. Therefore, developing improved animal osteomyelitis models is as important as developing new radioactive tracers. We recently published a review on radioactive tracers. In this review, we only present and discuss osteomyelitis models. Three ethical aspects (3R) are essential when exposing experimental animals to infections. Thus, we should perform experiments in vitro rather than in vivo (Replacement), use as few animals as possible (Reduction), and impose as little pain on the animal as possible (Refinement). The gain for humans should by far exceed the disadvantages for the individual experimental animal. To this end, the translational value of animal experiments is crucial. We therefore need a robust and well-characterized animal model to evaluate new osteomyelitis tracers to be sure that unpredicted variation in the animal model does not lead to a misinterpretation of the tracer behavior. In this review, we focus on how the development of radioactive tracers relies heavily on the selection of a reliable animal model, and we base the discussions on our own experience with a porcine model.

scholarly journals Animal Models in the Evaluation of the Effectiveness of Phage Therapy for Infections Caused by Gram-Negative Bacteria from the ESKAPE Group and the Reliability of Its Use in Humans

2021 ◽  
Vol 9 (2) ◽  
pp. 206
Author(s):  
Martyna Cieślik ◽  
Natalia Bagińska ◽  
Andrzej Górski ◽  
Ewa Jończyk-Matysiak
Keyword(s):  
Animal Models ◽  
Phage Therapy ◽  
Animal Experiments ◽  
Species Group ◽  
Effectiveness Evaluation ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Enterobacter Species ◽  
The Individual

The authors emphasize how extremely important it is to highlight the role played by animal models in an attempt to determine possible phage interactions with the organism into which it was introduced as well as to determine the safety and effectiveness of phage therapy in vivo taking into account the individual conditions of a given organism and its physiology. Animal models in which phages are used make it possible, among other things, to evaluate the effective therapeutic dose and to choose the possible route of phage administration depending on the type of infection developed. These results cannot be applied in detail to the human body, but the knowledge gained from animal experiments is invaluable and very helpful. We would like to highlight how useful animal models may be for the possible effectiveness evaluation of phage therapy in the case of infections caused by gram-negative bacteria from the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species) group of pathogens. In this review, we focus specifically on the data from the last few years.

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