1Institute of High Nerve Activity of Russian Academy of Sciences, Moscow, Russia; 2Kazan Federal University, Kazan, Russia; firstname.lastname@example.org
For a short period serotonin (5-HT) was identified as a neuromediator, both in molluscs, and in mammals. To the present time accumulated a great experimental material, indicating the connection of the functioning of serotoninergic system with the ability to learning (in the behavioral experiments). Therefore, it was conducted a study of the role of serotonin in the mechanisms of learning by behavioural and electrophysiological methods using the injections of neurotoxic analogues of serotonin 5,6 - 5,7-dihydroxytryptamine (5,6 - 5,7-DHT), the predecessor of the serotonin synthesis 5-dihydroxytryptamine (5-HTP) and by the analysis of changes in excitability (sensitivity) of command neurons to serotonin after the learning in terms of the electrical characteristics of the identified neurons. In these experiments have elaborated the defensive conditioned reflex (DCR) to tapping on the shell. It was found that the injection of 5,6-DHT inhibits the elaboration of DCR. At the same time daily injection predecessor of serotonin 5-HTP after injection of neurotoxin 5,7-DHT recovery the ability of the animal to learning. It was also shown that the injection of 5,6-DHT and 5.7-DHT causes a decrease of the membrane and threshold potentials of the command neurons, but also prevent their further decreasing during learning of snails after the injection of a 5.6-DHT without follow learning. It is found the restoration of the snails to learning through 2 weeks after the injection of 5,6-DHT. It was found that the application of serotonin causes the significant decrease of the membrane potential of the command neurons LPa3, RPa3, LPa2, RPa2 both intact (from -60.30.6 mV to -56.10.7 mV, n=15) and learned (from -56.30.3 mV to -53.40.8 mV, n=15) snails. However threshold potential in learned snails increases in response to application of serotonin (from 15.90.4 mV to 18.90.6 mV, n=11).