神經群活動記錄系統與其無線遙測技術之開發

Abstract

電生理技術一直是研究神經活動複雜行為的重要方法之一，其中的場電位與多神經元記錄方法所提供的資訊更是相輔相成。本論文先建構一可同時記錄場電位與多神經元信號之多通道記錄系統平台，並描述如何決定記錄電極的製作規格，且手工製作一作為大腦皮質急性穿刺記錄的多通道電極。多通道記錄系統中的信號調控單元分為三級組成，以達成較低的雜訊、低成本及良好的電流驅動能力等目的，在信號進入類比至數位轉換卡前則採取平行處理的濾波器設計架構，不需任何信號處理即能同時記錄場電位及多神經元信號，此系統中選擇購買一高速型64通道的類比至數位轉換介面卡及其相關軟體以完成在不同通道間近乎同步準確擷取的目的。最後，記錄大腦皮質區的反應信號以驗證其能滿足大範圍記錄的需求。 本論文的第二部份是建構了一簡單小型化無線遙測記錄系統，用於記錄大鼠自由活動時神經元的反應，其發射模組重量約只有大鼠體重的1%，所以不會對於大鼠移動時造成過多的負擔。這個系統具有長使用時間及等向性輻射等特性，滿足記錄動物自由活動反應的必要條件。另外，完成一低頻截止點到達6 Hz的調頻式接收器，以滿足記錄神經信號時所需之寬頻帶響應，其範圍包含了低頻的場電位信號。本論文詳細闡述設計這些系統時的考量因素及製作方法，希望能對其他從事相關研究的同好有所助益。

Electrophysiological techniques could help us to understand the complex behavior of neural activities. The conventional field potentials (FPs) and multi-unit activities (MUAs) recording are to complement each other. Firstly, a hybrid multichannel system was proposed to record FPs and MUAs. The detail procedures of microelectrode specification determination were described, and a custom-made electrode for the acute mapping of cerebral cortex was constructed. Moreover, a three-stage signal-conditioning unit was designed that offered low noise, low cost and excellent line-driving capabilities. The parallel architecture of the filter stage, just before the analog-to-digital (A/D) converter card, allowed the MUAs and FPs to be recorded simultaneously without further signal processing. To obtain a precision map, a 64-channel high-speed A/D card and its software program were purchased, which allowed “pseudo-synchronous” acquisition among different channels. Finally, the practical application of this system in investigating cortical responses showed that it met the requirements of ensemble recording. Secondly, a simple miniature telemetry system for neural recording from freely moving rats was described. It weighed only 1% of the body weight of an adult rat and shows no observable effects on the movement of the animal. Together with its long recording time (more than 38 h), its isotropic nature, which was essential for working with freely moving animals, offer further advantages. A frequency-modulation receiver with a flat frequency response down to 6 Hz had been designed for wide-spectrum recording of neural signals, allowed FPs recording. The detailed design considerations and methods for implementing the system could be valuable to other neuroscience laboratories.