Calcium and Spike Timing-Dependent Plasticity

Inglebert, Yanis; Debanne, Dominique

doi:10.3389/fncel.2021.727336

Cited by 27 publications

(25 citation statements)

References 106 publications

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“…Next, we wanted to examine whether the spike-based LPL rule is consistent with experimental observations of plasticity induction. Experiments commonly report intertwined rate and spiketiming dependence presumably mediated through nonlinear voltage- and calcium-dependent cellular mechanisms [28, 29, 47]. Theoretical work has further established conceptual links between phenomenological STDP models, SFA, and BCM theory [20, 48–52].…”

Section: Resultsmentioning

confidence: 99%

“…Thus, LPL qualitatively captures key phenomena observed in experiments such as STDP, the rate-dependence of plasticity, and metaplasticity, despite not being optimized to reproduce these phenomena. Rather our model offers a simple normative explanation for the necessity of different plasticity patterns that are also observed experimentally [47].…”

Section: Resultsmentioning

confidence: 99%

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The combination of Hebbian and predictive plasticity learns invariant object representations in deep sensory networks

Halvagal

Zenke

2022

Preprint

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Discriminating distinct objects and concepts from sensory stimuli is essential for survival. Our brains accomplish this feat by forming meaningful internal representations in deep sensory networks with plastic synaptic connections. Experience-dependent plasticity presumably exploits temporal contingencies between sensory inputs to build these internal representations. However, the precise mechanisms underlying plasticity remain elusive. We derive a local synaptic plasticity model inspired by self-supervised machine learning techniques that shares a deep conceptual connection to Bienenstock-Cooper-Munro (BCM) theory and is consistent with experimentally observed plasticity rules. We show that our plasticity model yields disentangled object representations in deep neural networks without the need for supervision and implausible negative examples. In response to altered visual experience, our model qualitatively captures neuronal selectivity changes observed in the monkey inferotemporal cortex in-vivo. Our work suggests a plausible learning rule to drive learning in sensory networks while making concrete testable predictions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The combination of Hebbian and predictive plasticity learns invariant object representations in deep sensory networks

Halvagal

Zenke

2022

Preprint

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“…Measurements of synaptic response in the “awake” ionic environment result in counterintuitive synaptic processing outcomes. The reduced Ca 2+ would be expected to decrease synaptic release ( Dodge and Rahamimoff, 1967 ) and does disrupt NMDAR-dependent synaptic plasticity in hippocampal slices ( Inglebert et al, 2020 ; Inglebert and Debanne, 2021 ). Although physiological ionic concentrations lead to decreased EPSP magnitudes, the NMDAR component amplified the response ( Figure 6 ).…”

Section: Discussionmentioning

confidence: 99%

Synaptic NMDA receptor activity at resting membrane potentials

Chiu

Carter

2022

Front. Cell. Neurosci.

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NMDA receptors (NMDARs) are crucial for glutamatergic synaptic signaling in the mammalian central nervous system. When activated by glutamate and glycine/D-serine, the NMDAR ion channel can open, but current flux is further regulated by voltage-dependent block conferred by extracellular Mg2+ ions. The unique biophysical property of ligand- and voltage-dependence positions NMDARs as synaptic coincidence detectors, controlling a major source of synaptic Ca2+ influx. We measured synaptic currents in layer 2/3 neurons after stimulation in layer 4 of somatosensory cortex and found measurable NMDAR currents at all voltages tested. This NMDAR current did not require concurrent AMPAR depolarization. In physiological ionic conditions, the NMDAR current response at negative potentials was enhanced relative to ionic conditions typically used in slice experiments. NMDAR activity was also seen in synaptic recordings from hippocampal CA1 neurons, indicating a general property of NMDAR signaling. Using a fluorescent Ca2+ indicator, we measured responses to stimulation in layer 4 at individual synaptic sites, and Ca2+ influx could be detected even with AMPARs blocked. In current clamp recordings, we found that resting membrane potential was hyperpolarized by ∼7 mV and AP firing threshold depolarized by ∼4 mV in traditional compared to physiological ionic concentrations, and that NMDARs contribute to EPSPs at resting membrane potentials. These measurements demonstrate that, even in the presence of extracellular Mg2+ and absence of postsynaptic depolarization, NMDARs contribute to synaptic currents and Ca2+ influx.

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“…This indicates that the amount of calcium entry per se is not the only variable determining the degree of potentiation. The kinetics and source of calcium entry may also influence potentiation ( Inglebert and Debanne, 2021 ; Zhou et al, 2005 ), as well as possible involvement of neuromodulators. See, for example, Gordon et al, 2006 , where we showed that in distal basal dendrites of layer 2–3 neocortical pyramidal neurons, brain-derived neurotrophic factor (BDNF) was a necessary requirement to gate plasticity in addition to calcium entry.…”

Section: Discussionmentioning

confidence: 99%

Plasticity of olfactory bulb inputs mediated by dendritic NMDA-spikes in rodent piriform cortex

Kumar

Barkai

Schiller

2021

eLife

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The piriform cortex (PCx) is essential for learning of odor information. The current view postulates odor learning in the PCx is mainly due to plasticity in intracortical (IC) synapses, while odor information from the olfactory bulb carried via the lateral olfactory tract (LOT) is 'hardwired'. Here we revisit this notion by studying location and pathway dependent plasticity rules. We find that in contrast to the prevailing view, synaptic and optogenetically activated LOT synapses undergo strong and robust long-term potentiation (LTP) mediated by only few local NMDA-spikes delivered at theta frequency, while global spike timing dependent plasticity protocols (STDP) failed to induce LTP in these distal synapses. In contrast, IC synapses in apical and basal dendrites undergo plasticity with both NMDA-spikes and STDP protocols but to a smaller extent compared with LOT synapses. These results are consistent with a self-potentiating mechanism of odor information via NMDA-spikes which can form branch-specific memory traces of odors that can further associate with contextual IC information via STDP mechanisms to provide cognitive and emotional value to odors.

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Calcium and Spike Timing-Dependent Plasticity

Cited by 27 publications

References 106 publications

The combination of Hebbian and predictive plasticity learns invariant object representations in deep sensory networks

The combination of Hebbian and predictive plasticity learns invariant object representations in deep sensory networks

Synaptic NMDA receptor activity at resting membrane potentials

Plasticity of olfactory bulb inputs mediated by dendritic NMDA-spikes in rodent piriform cortex

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