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Multi-channel Local Field Potentials-Spikes Spectrum Coherence Coding in Rat Prefrontal Cortex during Working Memory

Author: LiuTiaoTiao
Tutor: TianXin
School: Tianjin Medical University
Course: Biomedical Engineering
Keywords: Rats Working Memory events Multi-channel LFPs Multi-channel SPikes Spectrum coherent coding
CLC: R318.04
Type: Master's thesis
Year: 2011
Downloads: 60
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Abstract

Objective: modal brain nerve signals coding synergies between working memory events is neuroscience, cognitive science, information science, cross one of the research areas. This thesis rats in a working memory task, working memory Responsibility brain areas (prefrontal cortex) detected two different types modal multi-channel neural signal: continuous time sequence in the form of multi-channel local field potentials (Local Field Potentials, synergy between LFPs) and discrete point potential sequence in the form of multi-channel spike (Spikes) encoding, working memory events. The paper application LFPs-Spikes the Dynamic Spectrum coherent (Dynamic Spectrum Coherence, DSC) encoding method research support collaborative coding mode of working memory events provide experimental neural coding mechanism of working memory and neural computation. Methods: Animal experiments experimental animals for the Experimental Animal Center of the Chinese Academy of Medical Sciences, Institute of Radiation Medicine SD rats (8-10 weeks 20 ,300-350g), based on conscious animals in body microelectrode array multi-channel acquisition technology, application cerebus-128 rats were recorded in the body of multi-channel signal acquisition system, prefrontal cortex multi-channel neural signal in the Y-maze working memory task. 1) a rat Y maze working memory behavioral training rats working memory training in accordance with international norms: training twice a day, once 10 training tasks, each including rats were free to choose the direction of the Y-maze and anti- to select each time with a stopwatch to count under each task start and completion times, twice to select the interval 5-10s. The training lasted for two days in a row until the rat working memory tasks correct rate of greater than 80% as the standard of the Institute, has formed working memory. 2) in the body multi-channel micro electrode implantation surgery rats were anesthetized fixed in a stereotaxic apparatus, select the prefrontal cortex (to the the bregma point of reference, forward 2.5-4.5mm, next to open 0.2-1.0mm) open a rectangle window, implantable microelectrode array of 16 channels to reach the target brain areas skull after 2.5-3mm with dental cement fixed. 5-7 days postoperative recovery, testing began. 3) acquisition rat frontal cortex multi-channel application of neural signals in the working memory task Cerebus-128 multi-channel neural signals in a multi-channel neural signal the body recording system records each rat frontal cortex in the Y maze working memory task process . Each test record a complete process of working memory task. 2 multi-channel original data pretreatment on the original record data of the multi-channel low-pass filtered (0.3-500Hz), to obtain the multi-channel LFPS. Local linear regression using weighted least squares fitting methods to eliminate inclusions in the multi-channel LFPs signal baseline drift frequency interference, remove the reference in the original data differential record channel and drift over a major thoroughfare, for zero-mean multi-channel LFPs is a continuous time series. The multi-channel original recording data, high pass filtering (500-7500Hz), and then after the spike detection and offline addition to noise, multi-channel Spikes is the potential of the discrete points forms a discrete-time sequence. 3 multi-channel dynamic spectrum LFPs-Spikes coherent encoding 1) discrete point potential \converted to a continuous signal, this paper first discrete Spikes \Selected physiological window width of the window 500ms, window moves length of 125ms, from the initial point, the calculation the behavioral events before and after the reference point per channel within each window, the average rate of disbursement {R (T)}, and a frequency encoding and calculating its average payment number. 2) multi-channel LFPs and Spikes paired microelectrode array-based physical order of data preprocessing each electrode corresponding the LFPs and continuous Spikes pair, get data on multi-channel LFPs-Spikes. 3) multi-channel LFPs-Spikes the Dynamic Spectrum coherent coding select physiological window 500ms, moving step is 125ms, from the initial point individually discrete orthogonal flat ball sequence (Discrete Prolate Spheroidal Sequences, DPSS) on single-channel LFPs-Spikes sequence plus window, calculated for single-channel LFPs-Spikes data in each sliding window spectrum coherent values ??to calculate a multi-channel LFPs-Spikes the Dynamic Spectrum coherent values. Results: 1. Working memory behavior of rats in the Y-maze learning training results 20 rats, 17 in the Y-maze working memory task correct with the increase of the number of training to improve the correct rate after 10 days of training are maintained at above 80%. The remaining three rats can not meet the the Y maze of environmental and peanut odor working memory tasks can not be completed and removed. 2 rats in the Y-maze working memory task multi-channel raw data on 17 successful training rats prefrontal cortex surgically implanted in the body of multi-channel microelectrode array, record the completion of a working memory task in rats in the Y-maze multi-channel neural signals. 1) recorded at the same time to LFPs and Spikes and the number of channels of two rats greater than 12, more than one hundred times the completion of a working memory task: No. 1 rat 14-channel 15-channel, 2 rats; No. 3, -6, respectively 5,5,6,7 channel; 2) only recorded LFPs rat 5 records only 4 Spikes rats, 9 rats were unable to complete the pairing LFPs and Spieks, and removed; 3) the remaining The two rats no record LFPs and Spikes and removed. No. 1 and No. 2 rats typical results of this thesis 10 times each, the to select 10s (working memory before and after the event reference point 5s) as the main object of study. 3 multi-channel LFPs-Spikes dynamic spectrum coherent coding) spectrum of multi-channel LFPs coding: multi-channel the LFPs spectrum topographic map display, multi-channel LFPs energy distribution in the 0.3-15Hz. 2) multi-channel the Spikes frequency coding: multi-channel the Spikes frequency coding topographic map shows the average discharge rate of the multi-channel Spikes peak in 2-4s. 3) coherent coding of multi-channel spectrum LFPs-Spikes Rat 10 repetitions working memory task, multi-channel LFPs-Spikes in the first 2-4s ,0.3-15Hz frequency spectrum coherent value (0.6507 ± 0.012) and at other times, and frequency spectrum coherent value (0.3182 ± 0.0265), t-test, a significant difference (P lt; 0.05). 2 10 repetitions working memory task in rats, multi-channel LFPs-Spikes in the first 2-4s ,0.3-15Hz frequency spectrum coherent value (0.6541 ± 0.0071) and the other time and frequency spectrum coherent value (0.3248 ± 0.0061), t-test, there is a significant difference (P lt; 0.05). Conclusion: In this thesis, a multi-channel neural signals in the rat the Y maze of working memory behavior, study of the dynamic spectrum of multi-channel LFPs-Spikes coherent events on working memory encoding, the study results show that: 1 rat prefrontal cortex multi-channel LFPs-Spikes in the first 2-4s ,0.3-15Hz spectrum coherent values ??significantly higher than at other times (P lt; 0.05), indicating that the different modes of multi-channel neural signals occurred in the first 2-4s ,0.3-15Hz fixed phase of the oscillation, effectively encoding working memory events; predicted working memory events and in the working memory of the time before the reference point (5s). 2 multi-channel LFPs-Spikes the Dynamic Spectrum coherent coding the Spikes from two different modal the nerve signals synergistic angle, with the slow time scale continuous multi-channel the LFPs spectrum coding and fast time-scale discrete multi-channel frequency coding working memory event encoding complementary.

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