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Bi-directional interplay between proximal and distal inputs to CA2 pyramidal neurons
Kaoutsar Nasrallah1, Rebecca Ann Piskorowski1, Vivien Chevaleyre1
1CNRS UMR8118, Team Synaptic Plasticity and Neural Networks, FR3636, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints-Pères, 75006 Paris, France.
Neurobiology of Learning and Memory
|June 30, 2016
Summary
Plasticity in the hippocampus CA2 region is crucial for memory. Inhibitory synapse long-term depression, triggered by distal inputs, enhances excitatory drive, enabling CA2 pyramidal neuron recruitment for hippocampal information transfer.
Area of Science:
- Neuroscience
- Memory formation
- Hippocampal circuitry
Background:
- Hippocampal area CA2 is vital for memory.
- CA2 receives excitatory inputs from CA3 (Schaffer collateral - SC) and distal stratum lacunosum moleculare (SLM) regions.
- SC inputs to CA2 are tonically inhibited, limiting pyramidal neuron activation.
Purpose of the Study:
- To investigate plasticity at inhibitory synapses driven by distal SLM inputs in CA2.
- To determine if this plasticity modulates excitatory input strength to CA2 pyramidal neurons.
Main Methods:
- Electrophysiological recordings in hippocampal slices.
- Stimulation of SLM inputs to evoke plasticity.
- Assessment of excitatory and inhibitory synaptic transmission.
Main Results:
- Stimulation of SLM inputs induced long-term depression (LTD) at inhibitory synapses onto CA2 pyramidal neurons.
- This LTD significantly enhanced the excitatory drive from both proximal (SC) and distal (SLM) inputs.
- The plasticity facilitated the recruitment of CA2 pyramidal neurons by CA3 inputs.
Conclusions:
- Distal SLM inputs can induce plasticity at inhibitory synapses in CA2.
- This inhibitory plasticity strengthens excitatory drive, enabling CA2 neuron activation.
- A bidirectional interplay between proximal and distal inputs regulates information flow in CA2, crucial for hippocampal memory functions.
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