Long-Term Potentiation and Hebb's Postulate

LTP

Hebb's postulate

Coincident neuron activity strengthens synaptic connections.

Bliss & Lomo experiment

Demonstrated long-lasting synaptic potentiation in rabbits.

Long-Term Potentiation (LTP)

Persistent increase in synaptic strength following stimulation.

Inducing LTP

Requires specific stimulation patterns for synaptic changes.

Cooperativity

Simultaneous activation of multiple inputs triggers LTP.

Specificity

LTP occurs only at stimulated synapses.

Associativity

Weak inputs become significant with strong input pairing.

Hippocampal circuit

Pathway for information flow in memory processing.

Perforant pathway

Connects entorhinal cortex to hippocampus.

Granule cells

First synaptic connection in the hippocampal trisynaptic circuit.

CA3 pyramidal cells

Receive input from granule cells in LTP pathway.

CA1 pyramidal neurons

Final output neurons in hippocampal circuitry.

High-frequency stimulation (HFS)

Triggers significant synaptic strength increase.

Early LTP

Lasts 1-2 hours, induced by single high-frequency train.

Late LTP

Requires protein synthesis, lasts over 8 hours.

Spike-timing dependent plasticity (STDP)

Timing of spikes influences synaptic strength changes.

NMDA receptor

Critical for calcium influx during LTP induction.

L-type Ca2+ channels

Involved in both pre- and postsynaptic LTP mechanisms.

Presynaptic PKA-dependent LTP

Mechanism specific to mossy fiber-CA3 synapse.

Glutamate release

Essential for postsynaptic LTP induction.

Postsynaptic depolarization

Required alongside glutamate for LTP induction.

Synaptic tag

Captures gene expression products for LTP persistence.

Persistence of LTP

Can last for days, weeks, or months.

Kandel's readings

Key literature on LTP and memory mechanisms.

Frey & Morris study

Investigated synaptic tagging and LTP persistence.

Action potentials (APs)

Backpropagating APs enhance synaptic input strength.

EPSPs

Excitatory postsynaptic potentials contributing to LTP.

Tetanic burst

High-frequency stimulation used in LTP studies.

Memory substrate

Physiological basis for memory linked to LTP.