scholarly journals Long-term stability of cortical ensembles

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jesús Pérez-Ortega ◽  
Tzitzitlini Alejandre-García ◽  
Rafael Yuste
Keyword(s):  
Calcium Imaging ◽  
Pyramidal Neurons ◽  
Evoked Responses ◽  
Single Session ◽  
Long Term Stability ◽  
Neuronal Ensembles ◽  
Two Photon ◽  
Layer 2 ◽  
Over Time

Neuronal ensembles, coactive groups of neurons found in spontaneous and evoked cortical activity, are causally related to memories and perception, but it still unknown how stable or flexible they are over time. We used two-photon multiplane calcium imaging to track over weeks the activity of the same pyramidal neurons in layer 2/3 of the visual cortex from awake mice and recorded their spontaneous and visually evoked responses. Less than half of the neurons were commonly active across any two imaging sessions. These 'common neurons' formed stable ensembles lasting weeks, but some ensembles were also transient and appeared only in one single session. Stable ensembles preserved ~68 % of their neurons up to 46 days, our longest imaged period, and these 'core' cells had stronger functional connectivity. Our results demonstrate that neuronal ensembles can last for weeks and could, in principle, serve as a substrate for long-lasting representation of perceptual states or memories.

scholarly journals Long-term Transverse Imaging of the Hippocampus with Glass Microperiscopes

2021 ◽  
Author(s):  
William T Redman ◽  
Nora S Wolcott ◽  
Luca Montelisciani ◽  
Gabriel Luna ◽  
Tyler D Marks ◽  
...  
Keyword(s):  
Cognitive Processes ◽  
Calcium Imaging ◽  
Pyramidal Neurons ◽  
Spatial Information ◽  
Anatomical Distribution ◽  
Two Photon ◽  
Information Finding ◽  
Apical Dendrites

The hippocampus consists of a stereotyped neuronal circuit repeated along the septal-temporal axis. This transverse circuit contains distinct subfields with stereotyped connectivity that support crucial cognitive processes, including episodic and spatial memory. However, comprehensive measurements across the transverse hippocampal circuit in vivo are intractable with existing techniques. Here, we developed an approach for two-photon imaging of the transverse hippocampal plane in awake mice via implanted glass microperiscopes, allowing optical access to the major hippocampal subfields and to the dendritic arbor of pyramidal neurons. Using this approach, we tracked dendritic morphological dynamics on CA1 apical dendrites and characterized spine turnover. We then used calcium imaging to quantify the prevalence of place and speed cells across subfields. Finally, we measured the anatomical distribution of spatial information, finding a non-uniform distribution of spatial selectivity along the DG-to-CA1 axis. This approach extends the existing toolbox for structural and functional measurements of hippocampal circuitry.

scholarly journals Seizures start as silent microseizures by neuronal ensembles

2018 ◽  
Author(s):  
Michael Wenzel ◽  
Jordan P. Hamm ◽  
Darcy S. Peterka ◽  
Rafael MD Yuste
Keyword(s):  
Calcium Imaging ◽  
Travelling Wave ◽  
Inhibitory Neurons ◽  
Neural Activation ◽  
Calcium Dynamics ◽  
Neuronal Ensembles ◽  
Two Photon ◽  
Step Model

AbstractUnderstanding seizure formation and spread remains a critical goal of epilepsy research. While many studies have documented seizure spread, it remains mysterious how they start. We used fast in-vivo two-photon calcium imaging to reconstruct, at cellular resolution, the dynamics of focal cortical seizures as they emerge in epileptic foci (intrafocal), and subsequently propagate (extrafocal). We find that seizures start as intrafocal coactivation of small numbers of neurons (ensembles), which are electrographically silent. These silent “microseizures” expand saltatorily until they break into neighboring cortex, where they progress smoothly and first become detectable by LFP. Surprisingly, we find spatially heterogeneous calcium dynamics of local PV interneuron sub-populations, which rules out a simple role of inhibitory neurons during seizures. We propose a two-step model for the circuit mechanisms of focal seizures, where neuronal ensembles first generate a silent microseizure, followed by widespread neural activation in a travelling wave, which is then detected electrophysiologically.

Layer-specific involvement of endocannabinoid signaling in muscarinic-induced long-term depression in layer 2/3 pyramidal neurons of rat visual cortex

2019 ◽  
Vol 1712 ◽  
pp. 124-131 ◽  
Author(s):  
Kayoung Joo ◽  
Kwang-Hyun Cho ◽  
Sung-Hee Youn ◽  
Hyun-Jong Jang ◽  
Duck-Joo Rhie
Keyword(s):  
Visual Cortex ◽  
Pyramidal Neurons ◽  
Long Term Depression ◽  
Layer 2

scholarly journals Long-Term Stability and Reproducibility of Magnetic Colloids Are Key Issues for Steady Values of Specific Power Absorption over Time

2015 ◽  
Vol 2015 (27) ◽  
pp. 4444-4444
Author(s):  
Beatriz Sanz ◽  
M. Pilar Calatayud ◽  
Nicolás Cassinelli ◽  
M. Ricardo Ibarra ◽  
Gerardo F. Goya
Keyword(s):  
Specific Power ◽  
Power Absorption ◽  
Term Stability ◽  
Long Term Stability ◽  
Key Issues ◽  
Magnetic Colloids ◽  
Over Time

scholarly journals Texture coarseness responsive neurons and their mapping in layer 2–3 of the rat barrel cortex in vivo

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Liora Garion ◽  
Uri Dubin ◽  
Yoav Rubin ◽  
Mohamed Khateb ◽  
Yitzhak Schiller ◽  
...  
Keyword(s):  
Calcium Imaging ◽  
Barrel Cortex ◽  
Fundamental Function ◽  
Tactile Information ◽  
Hierarchical Processing ◽  
Two Photon ◽  
Columnar Organization ◽  
Layer 2 ◽  
Single Unit Recordings

Texture discrimination is a fundamental function of somatosensory systems, yet the manner by which texture is coded and spatially represented in the barrel cortex are largely unknown. Using in vivo two-photon calcium imaging in the rat barrel cortex during artificial whisking against different surface coarseness or controlled passive whisker vibrations simulating different coarseness, we show that layer 2–3 neurons within barrel boundaries differentially respond to specific texture coarsenesses, while only a minority of neurons responded monotonically with increased or decreased surface coarseness. Neurons with similar preferred texture coarseness were spatially clustered. Multi-contact single unit recordings showed a vertical columnar organization of texture coarseness preference in layer 2–3. These findings indicate that layer 2–3 neurons perform high hierarchical processing of tactile information, with surface coarseness embodied by distinct neuronal subpopulations that are spatially mapped onto the barrel cortex.

scholarly journals In-flight calibration results of the TROPOMI payload on-board theSentinel-5 Precursor satellite

2020 ◽  
Author(s):  
Antje Ludewig ◽  
Quintus Kleipool ◽  
Rolf Bartstra ◽  
Robin Landzaat ◽  
Jonatan Leloux ◽  
...  
Keyword(s):  
Dark Current ◽  
Light Sources ◽  
Radiometric Calibration ◽  
Monitoring Instrument ◽  
Long Term Stability ◽  
Angle Dependence ◽  
Flight Measurements ◽  
Solar Angle ◽  
Over Time

Abstract. After the launch of the Sentinel-5 Precursor satellite on 13 October 2017 its single payload, the Tropospheric Monitoring Instrument (TROPOMI), was commissioned during 6 months. In this time the instrument was tested and calibrated extensively. During this phase the geolocation calibration was validated using a dedicated measurement zoom mode. With the help of spacecraft manoeuvres the solar angle dependence of the irradiance radiometry was calibrated for both internal diffusers. This improved the results that were obtained on-ground significantly. Furthermore the orbital and long term stability was tested for electronic gains, offsets, non-linearity, the dark current and the output of the internal light sources. The CCD output gain of the UV, UVIS and NIR detectors shows drifts over time which can be corrected for in the L1b processor. In-flight measurements also revealed inconsistencies of the radiometric calibration and degradation of the UV spectrometer. Degradation is also detected for the internal solar diffusers. Since the start of the nominal operations (E2) phase in orbit 2818 on 30 April 2018, regularly scheduled calibration measurements on the eclipse side of the orbit are used for monitoring and updates to calibration key data. This article reports on the main results of the commissioning phase, the in-flight calibration and on the instrument's stability since launch. Insights from commissioning and in-flight monitoring led to updates to the Level 1b processor and its calibration key data. The updated processor is planned to be used for nominal processing from 2020 on.

scholarly journals FACTORS AFFECTING THE LONG-TERM STABILITY OF MICROWAVE OSCILLATORS FOR SPACE ELECTRONIC EQUIPMEN

2020 ◽  
Vol 258 (3) ◽  
pp. 77-81
Author(s):  
M. V. Kuliev
Keyword(s):  
Frequency Instability ◽  
External Factors ◽  
Signal Frequency ◽  
Factors Affecting ◽  
Term Stability ◽  
Long Term Stability ◽  
Microwave Oscillators ◽  
Main Factors ◽  
Over Time

Main factors affecting the long-term stability of microwave oscillator frequency are discussed in this paper. External factors affect the signal frequency at the output of any actual source, causing it to continuously change over time. Long-term frequency instability could be attributed to aging of the material. So, it is necessary to take special environmental factors into account, when designing microwave oscillators for space electronic equipment.

scholarly journals Hippocampal Egr1-dependent neuronal ensembles negatively regulate motor learning

2020 ◽  
Author(s):  
Veronica Brito ◽  
Enrica Montalban ◽  
Anika Pupak ◽  
Mercè Masana ◽  
Silvia Ginés ◽  
...  
Keyword(s):  
Motor Learning ◽  
Motor Skills ◽  
Pyramidal Neurons ◽  
Brain Regions ◽  
Learning Performance ◽  
Neuronal Ensembles ◽  
Neural Ensembles ◽  
Transcriptional Changes ◽  
Skills Learning

AbstractMotor skills learning is classically associated with brain regions including cerebral and cerebellar cortices and basal ganglia. Less is known about the role of the hippocampus in the acquisition and storage of motor skills. Here we show that mice receiving a long-term training in the accelerating rotarod display marked transcriptional changes in the striatum and hippocampus when compared with short-term trained mice. We identify Egr1 as a modulator of gene expression in the hippocampus during motor learning. Using mice in which neural ensembles are permanently labeled in an Egr1 activity-dependent fashion we identify ensembles of Egr1-expressing pyramidal neurons in CA1 activated in short- and long-term trained mice in the rotarod task. When Egr1 is downregulated or these neuronal ensembles are depleted, motor learning is improved whereas their chemogenetic stimulation impairs motor learning performance. Thus, Egr1 organizes specific CA1 neuronal ensembles during the accelerating rotarod task that limit motor learning.

scholarly journals Sensory cortical dynamics during optical microstimulation training

2021 ◽  
Author(s):  
Ravi Pancholi ◽  
Lauren Ryan ◽  
Simon P Peron
Keyword(s):  
Somatosensory Cortex ◽  
Calcium Imaging ◽  
Pyramidal Neurons ◽  
Cortical Activity ◽  
Sensory Cortex ◽  
Cortical Processing ◽  
Cortical Dynamics ◽  
Two Photon ◽  
Primary Sensory Cortex ◽  
Impact Perception

Primary sensory cortex is a key locus of plasticity during learning. Exposure to novel stimuli often alters cortical activity, but isolating cortex-specific dynamics is challenging due to extensive pre-cortical processing. Here, we employ optical microstimulation of pyramidal neurons in layer (L) 2/3 of mouse primary vibrissal somatosensory cortex (vS1) to study cortical dynamics as mice learn to discriminate microstimulation intensity. Tracking activity over weeks using two-photon calcium imaging, we observe a rapid sparsification of the photoresponsive population, with the most responsive neurons exhibiting the largest declines in responsiveness. Following sparsification, the photoresponsive population attains a stable rate of neuronal turnover. At the same time, the photoresponsive population increasingly overlaps with populations encoding whisker movement and touch. Finally, we find that mice with larger declines in responsiveness learn the task more slowly than mice with smaller declines. Our results reveal that microstimulation-evoked cortical activity undergoes extensive reorganization during task learning and that the dynamics of this reorganization impact perception.

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