Question

For long-term potentiation of synapses, if priming is not sufficient to dislodge Mg++ from NMDA receptor ion channels, what ions will not be able to pass through the channel? Also, if Mg++ is dislodged, what effects would NMDA activation have on the post-synaptic neuron?

Answer 1

Solution: If priming is not sufficient to dislodge Mg++ from NMDA receptor ion channels, Na+ and ca++ ions will not be able to pass through the channel. Actually, the AMPA receptors allow a rapid influx of Na+ into the postsynaptic cell, while the NMDA receptoreceptorsa slower and longer lasting influx of Na+. The NMDA receptors also require that the cell be somewhat depolarized through the action of other receptors before their pores will open and permit Na+ influx. When they do open, these receptors also allow Ca++ to enter the cell. Ca++ ions acts as second messagers in the cell and can trigger a variety of long term cellular changes.

# If Mg++ is dislodged from the NMDA receptors and allows Na+ and Ca++ to pass through them when they are activated by glutamate. These special properties of the NMDA receptors are probably involved in learning and memory. The NMDA activated, allowing both Na+ and Ca++ ions to enter the postsynaptic neurons. The Ca++ ions induce long term changes in the postsynaptic membrane that make it more sensitive to synaptic input.