Basic Mechanism for Generation of Brain Rhythms

腦波發生的基本原理與機轉

陳威宏(Wei-Hung Chen)

《Acta Neurologica Taiwanica》 13卷4期 (2004/12) Pp. 203-210

https://doi.org/10.29819/ANT.200412.0007

摘要

腦波反映大腦皮質於不同狀態下的電生理變化，提供我們作為探索大腦功能與神經網路運作的解讀工具。為了能掌握腦波提供的訊息與內含的意義，我們有必要認識與了解腦波的基本原理與發生機轉。腦波來自大腦皮質內大型錐體神經細胞的突觸後電位變化，由於大型錐體神經細胞及突觸的方向性，會產生雙極子，集合大腦表層一定範圍內有足夠數目的神經細胞能同一時問共振，才能由頭皮紀錄到腦波。腦波呈現規律性的律動，其發生機轉以睡眠紡錘波作研究對象，顯示視丘網狀細胞自發性規律放電，抑制視丘皮質投射細胞，因反彈放電而成周期性放電，透過回饋控制，產生紡錘波。Beta與gamma波被視為是覺醒與專注的代表腦波，在大腦活動增加或執行特定工作時，相關的局部大腦皮質之bet與gamma波會有增強的現象。Alpha波主要由大腦皮質產生，為鄰近皮質錐體細胞的連動，擴散與分布於皮質間。 Alpha波代表大腦皮質細胞暫時休息，處於蓄勢待發的狀態，是待命與率備的腦波。

關鍵字

腦電圖 ； 突觸後電位 ； 大腦皮質細胞 ； 視丘 ； 網狀賦活系統 ； 紡錘波

並列摘要

Study of the basic mechanism of brain rhythms adds to our understanding of the underlying processes of neuronal network within the human brain. Electroencephalography (EEG) records summated extracellular field potentials from large pyramidal neurons in the cerebral cortex. The characteristic rhythmic oscillation of brain rhythms are best studied by sleep spindles, which are generated within the thalamus through a network of thalamic reticular cells, thalamocortical projection cells and cortical pyramidal cells. Fast rhythms including beta and gamma are present during arousal and focused attention. Besides a reflection of activation from the brainstem reticular activating system, fast rhythms also represent an activated state of the underlying neuronal network. Alpha waves are readily recognized brain waves during relaxed wakefulness; however, the origins of alpha rhythm are not well understood. It is presumed that alpha rhythms are generated by contingent pyramidal cell, and by intracortical connections, spread in the cortical layers. Rhythmic alpha spindles probably represent a de-activated state.

並列關鍵字

Electroencephalogram ； Post-synaptic potentials ； Cortical pyramidal cells ； Thalamus ； Reticular activating system ； Sleep spindles