Question

Explain how Ca²⁺ could be involved in Hebbian strengthening of synapses.

Answer 1

Hebbain strengthening synapses is related to the theory in neuroscience that gives an explanation for the adaptation of neurons in the brain during the learning process. The adaptation of neurons during learning process is known as synaptic plasticity. The synaptic plasticity mechanism involves two type of receptors that are NMDA and AMPA glutamate receptors. Decreased cellular depolarization causes opening of NMDA channels which leads to a rise in post-synaptic Ca²⁺ concentration resulting in long term potentiation. Increased depolarization of the postsynaptic cell completely displaces the magnesium ions which block the NMDA channels and allow calcium ions to enter the cell and this is the probable cause of long term potentiation. Decreased cellular depolarization only partially displaces the magnesium ions, resulting in less entry of Ca²⁺ into the post-synaptic neuron and lower intracellular Ca²⁺ concentrations which activate protein phosphatases and induce long-term depression.