A Quantitative Study On The Behavior Of Avoiding Plantar Electric Shock In Normal And Dopamine Receptor Knockout Mice

Learning is an individual complex ability of animals that provides a subject with real-time feedback to its environmental affects.As a significant yet fundamental ability,learning increases environmental adaption of animals by responding to the environment with acquired behavioral alternations,in order to achieve ecological balance.For humans,learning results in maturity,stimulates intelligence,and development in psychological states.Learning is also a continuous process.Here,we define Connection Period as the first stage of learning,which is the understanding-to-understood period.It is an important period of learning,as it refers to the establishment of learning.Researchers of behaviorism observed the decrease of latency during animal learning,and simply describes the learning process with learning curve.However,these early researches did not address Connection Period,nor clearly define it.Set shifting experiments that study the learning ability of individuals switching between complex tasks requires a definition of "Fully learned" for test subjects,which normally defined as 6 to 10 continuously successful performances of the same task,thus Connection Period can be quantified accordingly.Consequently,Connection Period can be quantitatively studied by Set shifting experiments.On the other hand,there have been researches indicating reinforcement learning is closely related to dopamine-receptor-mediated direct and indirect neural pathways.And burst discharges are observed in the test subjects' dopaminergic neurons when the test subjects first encounter an unanticipated and exotic reward stimulus in reinforcement learning experiments.Although,the majority of reinforcement learning studies are based on positive reinforcement experiments,and only a few are done with negative reinforcement,that is,individual behavior reinforcement via removal of aversive stimulus.Recent studies suggest that both positive and negative reinforcement learning are essentially the same.Because unanticipated reward stimuli in positive reinforcements and unanticipated removal of aversive stimuli in negative reinforcements are both rewarding events for the test subject,and they both involve activity of dopaminergic neurons.As this reward-based unanticipated reinforcement learning occurs during the initial establishment of learning,namely,Connection Period,we hypothesize that dopaminergic neuron activity is highly involved in Connection Period.This research aims to quantitatively define Connection Period,estimate the involvement of dopamine in this period,and study the depression behaviors of dopamine knock-out animals,by utilizing skinnr box experiment,open field test,sucrose preference test,shuttle box test and forced swimming test combine with PCR and ISH test.And with using the literature research method and the statistical analysis method of the data results,the relevant literatures of the research questions are carefully reviewed and summarized,and the research results are accurately described.The study concluded the following:(1)In negative reinforcement learning task,the connection period of normal animals respectively occurred more quickly and shorter than dopamine D1R D2R knockout mice,and the average time is 1000s compared with 2000s.At the end of the connection period,normal mice can remain at a stable level of learning and are no longer prone to errors.(2)The connection period of dopamine D1R or D2R knockout animals was difficult to establish,and the connection period was delayed.In the negative reinforcement learning task,the mice showed difficulty in learning and were prone to error with 20%error rate on average,while the dopamine DIR and D2R knockout mice had an average error rate of 45%,indicating that dopamine has an important influence on the connection period.D1R and D2R have a key role in cognitive processes.(3)Dopamine D1R and D2R knockout mice will produce obvious depression-like behavior.Compared with normal mice,they showed a decrease in the number of licking sucrose water and a long escape latency.Among them,D2R knockout animals are more obvious.This indicates that dopamine is closely related to depression-like behavior.This study conducted a quantitative research of the understanding-to-understood period,which is the connection period,through the negative reinforcement learning experiment.This study demonstrated the important role of dopaminergic neurons in this learning phase by exploring the important role of dopamine in this learning phase and observing the depression-like manifestations of dopamine receptor knockout animals.This study helps to better understand the process of learning behavior,and lays a foundation for further study of the neural mechanism of the connection period.It also helps to better understand the role of dopamine in learning loss.