scholarly journals Shaping dendritic NMDA spikes by timed synaptic inhibition: Implications for the I/O properties of cortical neurons

2017 ◽  
Author(s):  
Michael Doron ◽  
Giuseppe Chindemi ◽  
Eilif Muller ◽  
Henry Markram ◽  
Idan Segev
Keyword(s):  
System Theory ◽  
Cortical Neurons ◽  
Time Course ◽  
Synaptic Inhibition ◽  
Spike Time ◽  
Gabaergic Synapse ◽  
Computational Approaches ◽  
Dynamic System Theory ◽  
Different Types ◽  
Dendritic Branches

The pronounced, long lasting, regenerative NMDA-spike is initiated in individual dendritic branches of different types of neurons and is known to play a key role in dendritic computations and plasticity. Combining dynamic system theory and computational approaches, we systematically analyzed how timed synaptic inhibition activated during the NMDA-spike time-course, sculpts this spike and its associated current influx. When impinging on its early phase, individual GABAergic synapse activation transiently, but strongly, dampened the NMDA-spike; later inhibition prematurely terminated it. This inhibition reduced the NMDA-mediated Ca2+ current by up to 60%. NMDA-spikes in distal dendritic branches/spines are longer lasting and more resilient to inhibition, and thus enhance synaptic plasticity at these branches. Examination of this sensitivity of the NMDA-spike to well-timed synaptic inhibition suggests that NMDA-spikes are highly modifiable signals which enable sparse weak distal dendritic inhibition to finely tune both the neuron's output spikes as well as the branch's/spine's Ca2+ current associated with the local NMDA spike.

Transforming by Following Forces: Introducing Chinese Philosophy of SHI and SHUN SHI into Developmental and Educational Psychology

2021 ◽  
pp. 1354067X2110173
Author(s):  
Aruna Wu ◽  
Shuangshuang Xu ◽  
Xiaowen Li
Keyword(s):  
System Theory ◽  
Educational Intervention ◽  
Educational Psychology ◽  
Chinese Philosophy ◽  
Zone Of Proximal Development ◽  
Proximal Development ◽  
Dynamic System Theory ◽  
Alternative Perspective ◽  
Process Understanding ◽  
Long Time

Educational intervention has been narrated for a long time as a battle between two agentive subjects, educators and students. In this article, we introduce two interrelating concepts of SHI (势 in Chinese) and SHUN SHI (顺势 in Chinese) from Chinese philosophy into psychology to provide an alternative perspective to understand students’ development and educational intervention. The concept of SHI sheds light on the propensity of open system’s becoming process toward the future underlying system’s present configuration derived from system’s historical interaction with its environment. SHUN SHI is to grasp the opportunity of SHI evolving into being prominent and to transform the system by alertly following its unfolding process. Understanding and applying SHI and SHUN SHI in the area of developmental and educational psychology is discussed and clarified based on a comparison with the dynamic system theory and zone of proximal development. An empirical research is also provided to respond to the method challenge posed by the two concepts.

Dynamic coupling among neocortical neurons during evoked and spontaneous spike-wave seizure activity

1994 ◽  
Vol 72 (5) ◽  
pp. 2051-2069 ◽  
Author(s):  
M. Steriade ◽  
F. Amzica
Keyword(s):  
Cortical Neurons ◽  
Time Course ◽  
Early Stage ◽  
Field Potential ◽  
Time Lags ◽  
Temporal Relations ◽  
Intracellular Recordings ◽  
Field Potentials ◽  
Thalamic Nuclei ◽  
Spike Wave

1. We investigated the development from patterns of electroencephalogram (EEG) synchronization to paroxysms consisting of spike-wave (SW) complexes at 2–4 Hz or to seizures at higher frequencies (7–15 Hz). We used multisite, simultaneous EEG, extracellular, and intracellular recordings from various neocortical areas and thalamic nuclei of anesthetized cats. 2. The seizures were observed in 25% of experimental animals, all maintained under ketamine and xylazine anesthesia, and were either induced by thalamocortical volleys and photic stimulation or occurred spontaneously. Out of unit and field potential recordings within 370 cortical and 65 thalamic sites, paroxysmal events occurred in 70 cortical and 8 thalamic sites (approximately 18% and 12%, respectively), within which a total of 181 neurons (143 extracellular and 38 intracellular) were simultaneously recorded in various combinations of cell groups. 3. Stimulus-elicited and spontaneous SW seizures at 2–4 Hz lasted for 15–35 s and consisted of barrages of action potentials related to the spiky depth-negative (surface-positive) field potentials, followed by neuronal silence during the depth-positive wave component of SW complexes. The duration of inhibitory periods progressively increased during the seizure, at the expense of the phasic excitatory phases. 4. Intracellular recordings showed that, during such paroxysms, cortical neurons displayed a tonic depolarization (approximately 10–20 mV), sculptured by rhythmic hyperpolarizations. 5. In all cases, measures of synchrony demonstrated time lags between discharges of simultaneously recorded cortical neurons, from as short as 3–10 ms up to 50 ms or even longer intervals. Synchrony was assessed by cross-correlograms, by a method termed first-spike-analysis designed to detect dynamic temporal relations between neurons and relying on the detection of the first action potential in a spike train, and by a method termed sequential-field-correlation that analyzed the time course of field potentials simultaneously recorded from different cortical areas. 6. The degree of synchrony progressively increased from preseizure sleep patterns to the early stage of the SW seizure and, further, to its late stage. In some cases the time relation between neurons during the early stages of seizures was inversed during late stages. 7. These data show that, although the common definition of SW seizures, regarded as suddenly generalized and bilaterally synchronous activities, may be valid at the macroscopic EEG level, cortical neurons display time lags between their rhythmic spike trains, progressively increased synchrony, and changes in the temporal relations between their discharges during the paroxysms.(ABSTRACT TRUNCATED AT 400 WORDS)

Temporal Dynamics of Shape Analysis in Macaque Visual Area V2

2004 ◽  
Vol 92 (5) ◽  
pp. 3030-3042 ◽  
Author(s):  
Jay Hegdé ◽  
David C. Van Essen
Keyword(s):  
Cortical Neurons ◽  
Time Course ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
Signal To Noise Ratio ◽  
Stimulus Onset ◽  
Visual Area ◽  
Response Modulation ◽  
Population Response ◽  
Area V2

The firing rate of visual cortical neurons typically changes substantially during a sustained visual stimulus. To assess whether, and to what extent, the information about shape conveyed by neurons in visual area V2 changes over the course of the response, we recorded the responses of V2 neurons in awake, fixating monkeys while presenting a diverse set of static shape stimuli within the classical receptive field. We analyzed the time course of various measures of responsiveness and stimulus-related response modulation at the level of individual cells and of the population. For a majority of V2 cells, the response modulation was maximal during the initial transient response (40–80 ms after stimulus onset). During the same period, the population response was relatively correlated, in that V2 cells tended to respond similarly to specific subsets of stimuli. Over the ensuing 80–100 ms, the signal-to-noise ratio of individual cells generally declined, but to a lesser degree than the evoked-response rate during the corresponding time bins, and the response profiles became decorrelated for many individual cells. Concomitantly, the population response became substantially decorrelated. Our results indicate that the information about stimulus shape evolves dynamically and relatively rapidly in V2 during static visual stimulation in ways that may contribute to form discrimination.

Synaptic Interactions Between Thalamic and Cortical Inputs Onto Cortical Neurons In Vivo

2004 ◽  
Vol 91 (5) ◽  
pp. 1990-1998 ◽  
Author(s):  
Pablo Fuentealba ◽  
Sylvain Crochet ◽  
Igor Timofeev ◽  
Mircea Steriade
Keyword(s):  
Cortical Neurons ◽  
Time Course ◽  
Input Resistance ◽  
Maximal Effect ◽  
Time Intervals ◽  
Neocortical Neurons ◽  
Synaptic Interactions ◽  
Cortical Responses ◽  
Cortical Inputs

To study the interactions between thalamic and cortical inputs onto neocortical neurons, we used paired-pulse stimulation (PPS) of thalamic and cortical inputs as well as PPS of two cortical or two thalamic inputs that converged, at different time intervals, onto intracellularly recorded cortical and thalamocortical neurons in anesthetized cats. PPS of homosynaptic cortico-cortical pathways produced facilitation, depression, or no significant effects in cortical pathways, whereas cortical responses to thalamocortical inputs were mostly facilitated at both short and long intervals. By contrast, heterosynaptic interactions between either cortical and thalamic, or thalamic and cortical, inputs generally produced decreases in the peak amplitudes and depolarization area of evoked excitatory postsynaptic potentials (EPSPs), with maximal effect at ∼10 ms and lasting from 60 to 100 ms. All neurons tested with thalamic followed by cortical stimuli showed a decrease in the apparent input resistance ( Rin), the time course of which paralleled that of decreased responses, suggesting that shunting is the factor accounting for EPSP's decrease. Only half of neurons tested with cortical followed by thalamic stimuli displayed changes in Rin. Spike shunting in the thalamus may account for those cases in which decreased synaptic responsiveness of cortical neurons was not associated with decreased Rin because thalamocortical neurons showed decreased firing probability during cortical stimulation. These results suggest a short-lasting but strong shunting between thalamocortical and cortical inputs onto cortical neurons.

scholarly journals Development of Thalamocortical Response Transformations in the Rat Whisker-Barrel System

2008 ◽  
Vol 99 (1) ◽  
pp. 356-366 ◽  
Author(s):  
Michael Shoykhet ◽  
Daniel J. Simons
Keyword(s):  
Cortical Neurons ◽  
Time Course ◽  
Receptive Fields ◽  
Second Phase ◽  
Adult Rats ◽  
Response Latencies ◽  
Thalamic Neurons ◽  
Response Properties ◽  
Temporal Domain

Extracellular single-unit recordings were used to characterize responses of thalamic barreloid and cortical barrel neurons to controlled whisker deflections in 2, 3-, and 4-wk-old and adult rats in vivo under fentanyl analgesia. Results indicate that response properties of thalamic and cortical neurons diverge during development. Responses to deflection onsets and offsets among thalamic neurons mature in parallel, whereas among cortical neurons responses to deflection offsets become disproportionately smaller with age. Thalamic neuron receptive fields become more multiwhisker, whereas those of cortical neurons become more single-whisker. Thalamic neurons develop a higher degree of angular selectivity, whereas that of cortical neurons remains constant. In the temporal domain, response latencies decrease both in thalamic and cortical neurons, but the maturation time-course differs between the two populations. Response latencies of thalamic cells decrease primarily between 2 and 3 wk of life, whereas response latencies of cortical neurons decrease in two distinct steps—the first between 2 and 3 wk of life and the second between the fourth postnatal week and adulthood. Although the first step likely reflects similar subcortical changes, the second phase likely corresponds to developmental myelination of thalamocortical fibers. Divergent development of thalamic and cortical response properties indicates that thalamocortical circuits in the whisker-to-barrel pathway undergo protracted maturation after 2 wk of life and provides a potential substrate for experience-dependent plasticity during this time.

scholarly journals Neural Encoding of Attended Continuous Speech under Different Types of Interference

2018 ◽  
Vol 30 (11) ◽  
pp. 1606-1619 ◽  
Author(s):  
Andrea Olguin ◽  
Tristan A. Bekinschtein ◽  
Mirjana Bozic
Keyword(s):  
Selective Attention ◽  
Time Course ◽  
Strong Support ◽  
Neural Encoding ◽  
Continuous Speech ◽  
Auditory Selective Attention ◽  
Different Types ◽  
Cross Correlations ◽  
Different Depths ◽  
Eeg Recordings

We examined how attention modulates the neural encoding of continuous speech under different types of interference. In an EEG experiment, participants attended to a narrative in English while ignoring a competing stream in the other ear. Four different types of interference were presented to the unattended ear: a different English narrative, a narrative in a language unknown to the listener (Spanish), a well-matched nonlinguistic acoustic interference (Musical Rain), and no interference. Neural encoding of attended and unattended signals was assessed by calculating cross-correlations between their respective envelopes and the EEG recordings. Findings revealed more robust neural encoding for the attended envelopes compared with the ignored ones. Critically, however, the type of the interfering stream significantly modulated this process, with the fully intelligible distractor (English) causing the strongest encoding of both attended and unattended streams and latest dissociation between them and nonintelligible distractors causing weaker encoding and early dissociation between attended and unattended streams. The results were consistent over the time course of the spoken narrative. These findings suggest that attended and unattended information can be differentiated at different depths of processing analysis, with the locus of selective attention determined by the nature of the competing stream. They provide strong support to flexible accounts of auditory selective attention.

Latitude Dependent Circadian Rhythms of Carabid Beetles

1986 ◽  
Vol 41 (9-10) ◽  
pp. 935-945
Author(s):  
Gisela Leyk ◽  
Wolfgang Martin
Keyword(s):  
Time Course ◽  
Activity Patterns ◽  
Carabid Beetles ◽  
Constant Darkness ◽  
Spectrum Estimation ◽  
Program System ◽  
Central European ◽  
Light Pulses ◽  
Different Types ◽  
Periodogram Analysis

Abstract Comparative studies of circadian activity rhythms were performed with three stocks of the species Pterostichus rhaeticus Heer (from Southern Europe, Central Europe, and the Subarctic) and with one Central European stock of the sibling species Pterostichus nigrita Paykull. The hehaviour was investigated in various LD conditions, constant conditions including LL with changes of the illumination intensity and constant darkness with light pulses. The data were analysed with the program system “Timesdia” containing various techniques like power spectrum estimation, periodogram analysis and complex demodulation. This allowed to reveal the time course of rhythms and to determine the number of phase jumps as a measure for precision. With the help of these methods, the activity patterns are classified in different types of behaviour: synchronization, temporarily synchronization, aperiodic behaviour, free run, temporarily free run, relative entrainment, and relative coordination. Besides graduated differences between the populations in south-to-north direction (e.g. in the tendency to rhythmic behaviour) the analysis revealed splitting of rhythms into two or even three components of different frequencies and transitions from rhythmic to aperiodic behaviour or vice versa after arbitrarily chosen light pulses in constant darkness. This behaviour cannot be explained by a system which is composed of one single limit cycle oscillator, but the results rather support a multi-oscillator model.

scholarly journals Calculating Event-Triggered Average Synaptic Conductances From the Membrane Potential

2007 ◽  
Vol 97 (3) ◽  
pp. 2544-2552 ◽  
Author(s):  
Martin Pospischil ◽  
Zuzanna Piwkowska ◽  
Michelle Rudolph ◽  
Thierry Bal ◽  
Alain Destexhe
Keyword(s):  
Membrane Potential ◽  
Cortical Neurons ◽  
Time Course ◽  
Spike Generation ◽  
Nonlinear Contribution ◽  
Central Neurons ◽  
Time Courses ◽  
Model Subject ◽  
Synaptic Conductances

The optimal patterns of synaptic conductances for spike generation in central neurons is a subject of considerable interest. Ideally such conductance time courses should be extracted from membrane potential ( Vm) activity, but this is difficult because the nonlinear contribution of conductances to the Vm renders their estimation from the membrane equation extremely sensitive. We outline here a solution to this problem based on a discretization of the time axis. This procedure can extract the time course of excitatory and inhibitory conductances solely from the analysis of Vm activity. We test this method by calculating spike-triggered averages of synaptic conductances using numerical simulations of the integrate-and-fire model subject to colored conductance noise. The procedure was also tested successfully in biological cortical neurons using conductance noise injected with dynamic clamp. This method should allow the extraction of synaptic conductances from Vm recordings in vivo.

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