Research On The Response Rroperties Of Hippocampal Place Cells To Target Location In Place Preference Task

The encoding of spatial location is crucial to the survival of both animals and humans.Current studies have shown that the hippocampus region plays a key role in spatial location representation.Hippocampus place cells and their firing fields are considered to be the basis units of spatial cognitive map.If the firing field of place cells reflects the current location of the animal in space,then it is still necessary to further study whether the target location,as the key information of spatial navigation,is also represented by the hippocampus place cells.Further research on the response properties of hippocampus place cells to target location is not only of great significance for the analysis of the neural mechanism of spatial navigation,but also provides theoretical support for the research in the field of bionics and robotics.With regard to the response properties of hippocampal place cells to target locations,pigeons were selected as experimental animals for their excellent spatial abilities.Based on a place preference task,a multi-channel microelectrode array was implanted to record the nerve signals in the hippocampus,and the place cells were identified and screened by combining spatial information rate and two-pass algorithm.In addition,a target marker change experiment and a target location change experiment were designed respectively to investigate the effects of target marker change,target presence or absence and target location change on the response properties of place cells.Specifically summarized as follows:(1)In order to make the information represented by the target more specific,a place preference task was designed which separated the reward from target zone.The experimental system,which integrates the functions of automatic feeding,real-time recording of pigeon movement trajectory and synchronous collection of pigeon nerve signals,has been built to reduce the interference of human activities in the experiment.(2)Based on the non-stationary and local amplitude jump characteristics of spike signals,a spike sorting method based on unsupervised local adaptive projection feature selection algorithm and Gaussian mixture model clustering algorithm is adopted.Then a screening method based on spatial information rate and two-pass algorithm is used to improve the effective recognition of place cells.(3)In order to investigate the response properties of pigeons hippocampal palce cells to target location in a target marker changing environment,a target marker changing experiment was designed in this paper.The results emphasized that pigeons could correctly remember the target location in the presence or absence of the marker,and the firing field of place cells was significantly aggregated around the target zone.However,the accuracy of target recognition and the aggregation degree of place field around the target were decreased in non-marker stage.(4)To study the response properties of hippocampal place cells in the environment with target location change,a target location change experiment was designed to record and analyze the behavioral data and neural activities of pigeons in three stages.The results indicated that pigeons were more likely to induce place cells in a targeted environment,and their place fields were clustered around the target zone.When the target location changed,the firing field of the neurons came closer to the new target location.