Activity-Dependent Presynaptic Facilitation and Hebbian LTP Are Both Required and Interact during Classical Conditioning in Aplysia

  title={Activity-Dependent Presynaptic Facilitation and Hebbian LTP Are Both Required and Interact during Classical Conditioning in Aplysia},
  author={I. N. Antonov and Irina Antonova and Eric R. Kandel and Robert X. D. Hawkins},

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Behavioral / Systems / Cognitive Synaptic Facilitation and Behavioral Dishabituation in Aplysia : Dependence on Release of Ca 2 from Postsynaptic Intracellular Stores , Postsynaptic Exocytosis , and Modulation of Postsynaptic AMPA Receptor Efficacy

It is shown that facilitation of sensorimotor synapses in cell culture during and after serotonin (5-HT) exposure depends on a rise in postsynaptic intracellular Ca2+ and release of Ca2+, and the idea that post Synaptic AMPA receptor insertion mediates a component of synaptic facilitation is provided.

Comparison of the ionic currents modulated during activity-dependent and normal presynaptic facilitation.

The results suggest that an associative form of plasticity, activity-dependent presynaptic facilitation underlying conditioning, involves enhanced modulation of the same ionic current as a nonassociative form, normal presyapticfacilitation underlying sensitization.

Learning insights transmitted by glutamate

Associative learning in invertebrates.

Research is reviewed on neural mechanisms of two types of associative learning in the marine mollusk Aplysia, classical conditioning of the gill- and siphon-withdrawal reflex and operant conditioning of feeding behavior, which involves many of the same mechanisms, which may contribute to learning in vertebrates as well.

The other side of the engram: experience-driven changes in neuronal intrinsic excitability

The evidence for persistent changes in intrinsic neuronal excitability — what the authors will call intrinsic plasticity — that is produced by training in behaving animals and by artificial patterns of activation in brain slices and neuronal cultures is considered.

Burst-Induced Synaptic Depression and Its Modulation Contribute to Information Transfer at Aplysia Sensorimotor Synapses: Empirical and Computational Analyses

Substantial enhancement of synaptic transmission throughout a burst increased motor neuron output substantially more than did preferential enhancement of the initial phase of a burst, indicating that synaptic depression increased the dynamic range of the sensorimotor synapse and can, in principle, have a profound effect on information processing.

Multiple Forms of Long-Term Potentiation and Long-Term Depression Converge on a Single Interneuron in the Leech CNS

LTP was observed in two types of synapses that converge on the same postsynaptic neuron in the leech CNS, and leech neurons exhibit synaptic plasticity with properties similar to LTP and LTD found in the vertebrate nervous system.



Mediation of classical conditioning in Aplysia californica by long-term potentiation of sensorimotor synapses.

A cellular analog of classical conditioning in Aplysia was used to determine whether this form of invertebrate learning involves N-methyl-D-aspartate (NMDA)-type LTP, and NMDA receptor-antagonist dl-2-amino-5-phosphonovalerate significantly disrupted synaptic enhancement after associative training but did not disrupt synaptic Enhancement after nonassociative training.

The Contribution of Activity-Dependent Synaptic Plasticity to Classical Conditioning in Aplysia

Paired training of the Aplysia siphon withdrawal reflex with a siphon tap conditioned stimulus and tail shock unconditioned stimulus provides the most direct evidence to date that activity-dependent plasticity at specific central synapses contributes to behavioral conditioning and support the idea that synaptic plasticity is a mechanism of learning and memory more generally.

Pairing-specific, activity-dependent presynaptic facilitation at Aplysia sensory-motor neuron synapses in isolated cell culture

The findings indicate that the mechanism underlying associative, activity-dependent facilitation is intrinsic to the sensory neuron synapse, that it is presynaptically mediated by processes unique to evoked synaptic transmission, and that it appears to involve a pairing-specific broadening of the presynaptic action potential.

Involvement of Presynaptic and Postsynaptic Mechanisms in a Cellular Analog of Classical Conditioning at AplysiaSensory-Motor Neuron Synapses in Isolated Cell Culture

The results suggest that pairing-specific facilitation by serotonin involves Hebbian postsynaptic as well as non-Hebbian presynaptic components that interact in some way, perhaps via retrograde signaling, to specifically enhance evoked, synchronized release of transmitter.

Hebbian synapses in hippocampus.

The demonstrated spatiotemporal specificity of this pseudo-Hebbian conjunctive mechanism can account qualitatively for the known neurophysiological properties of associative long-term potentiation in these synapses, which in turn can explain the "cooperativity" requirement for long- term potentiation.

Activity-dependent enhancement of presynaptic facilitation provides a cellular mechanism for the temporal specificity of classical conditioning in Aplysia.

Results suggest that temporally specific synaptic enhancement engages both spike-width-dependent and spike- width-independent facilitatory processes and that activity-dependent enhancement of presynaptic facilitation may contribute to both the CS-US sequence and proximity requirements of conditioning.

A cellular mechanism of classical conditioning in Aplysia: activity-dependent amplification of presynaptic facilitation.

Results of these cellular experiments are quantitatively similar to the results of behavioral experiments with the same protocol and parameters, suggesting that activity-dependent amplification of presynaptic facilitation may make a significant contribution to classical conditioning of the withdrawal reflex.

Enhancement of sensorimotor connections by conditioning-related stimulation in Aplysia depends upon postsynaptic Ca2+.

  • G. MurphyD. Glanzman
  • Biology, Psychology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1996
The results implicate a postsynaptic, possibly Hebbian, mechanism in classical conditioning in Aplysia following paired presentations of sensory neuron activation and tail nerve shock.

Effect of interstimulus interval on pairing-induced LTP of Aplysia sensorimotor synapses in cell culture.

It is indicated that Hebbian apLTP alone cannot fully account for classical conditioning in Aplysia and an additional cellular mechanism is required to explain the temporal specificity present in the behavioral results.

Long-term potentiation of Aplysia sensorimotor synapses in cell culture: regulation by postsynaptic voltage

It is reported that high-frequency stimulation can induce LTP of sensorimotor synapses of the marine mollusc Aplysia in cell culture and appears to involve a voltage-dependent postsynaptic mechanism.