Cortexin is a clinically approved cerebral cortex polypeptide complex in calves. The mechanism of cortexin action is not understood well. Two cortexin derivatives, short peptides EDR and DS with neuroprotective activity, were synthesized. According to the data of molecular modeling, these peptides are able to bind to the histone H1.3 protein. This can affect the conformation of histone H1.3, which leads to a change in the chromatin structure in the loci of some genes, in particular Fkbp1b encoding the FK506-binding protein. Electrophysiological processes associated with the Ca²⁺ exchange are disturbed in the pyramidal neurons of the hippocampus during aging of the brain. The Fkbp1b gene encodes peptidyl-prolyl cis-trans isomerase, regulating the release of calcium ions from the sarcoplasmic and endoplasmic reticulum of neurons. The activation of the Fkbp1b gene transcription under treatment with short peptides can promote the synthesis of its protein product and the activation of the Ca²⁺ release from organelles of the sarcoplasmic and endoplasmic reticulum of neurons, which, in turn, can lead to an increase in the functional activity of neurons.