These changes also result in insertion of AMPA receptors in the postsynaptic neuron, but, more importantly, they lead to protein modification and synthesis which allows for pruning of synapses. In the long term changes, prolonged calcium influx influences transcription factors, which impact protein synthesis.
In the short term changes, which last only a few hours, calcium binds to proteins which result in insertion of AMPA receptors onto the postsynaptic cell. Cell Layers 3 main layers of hippocampus proper 3. Major components of the hippocampal formation Hippocampal proper (CA1,CA2,CA3) Pes hippocampus Para hippocampus gurus Dentate gyrus Entorhinal cortex Subiculum Presubiculum Parasubiculum 5. This influx of calcium activates protein kinases and triggers cascades that contribute to two types of changes: short term and long term. Primates have two Hippocampus on each side of the hemispheres. Ammon’s horn is connected with the subiculum, that serves as the main output source of the hippocampal generation. It is split into three fields (CA1, CA2, and CA3) which process, send and receive input from different brain regions. However, this large depolarization triggered by the activation of the AMPA receptor can displace the magnesium, which will allow sodium and calcium to enter into the postsynaptic cell. Ammon’s horn is another name for the hippocampus proper or hippocampus major. Though the NMDA receptors are both sodium and calcium permeable, they cannot be activated upon low frequency stimulation because at the resting membrane potential, they experience a magnesium block. This will result in a large amount of sodium entry and will create a large depolarization, which is key for activation of the NMDA receptors. However, if the action potential that travels down the collateral has a high enough frequency, a large amount of glutamate will be released, which will allow the AMPA receptors to remain open for extended periods of time, longer than a low frequency stimulation would allow. This sodium influx results in a depolarization, which may not be strong enough to do anything. Upon stimulation, the AMPA receptors open, and sodium is allowed to travel through the channel and into the postsynaptic membrane. Both are glutamate receptors NMDA receptors are sodium and calcium permeable, while AMPA receptors are permeable only to sodium. This glutamate release stimulates two important receptors, AMPA and NMDA. The entire process begins with action potentials, which travel down the Schaffer collaterals and trigger glutamate release into the synaptic cleft.