Chapter 10 神經生理學 | ||
Communication between neurons of the nervous system occurs at the synapse, and neurotransmitter passing through the synaptic cleft will either excite or inhibit the postsynaptic neuron. When sufficiently stimulated an action potential will be generated, causing membrane depolarization and exchange of ions between the extracellular and intracellular space. Ion movement results in a large and predictable change in voltage across the membrane. Resting membrane potential is the relatively stable state of the neuron at rest, while the absolutely refractory periods, after excitation, is an interval during which the neuron may not be excited to fire. During the relatively refractory period a neuron may be stimulated to fire, given increased stimulation. Neurons are capable of representing differences in input only through rate of response. Myelinted fibers conduct the wave of depolarization more rapidly than demyelinated fibers, primarily due to saltatory conduction. 溝通的發生位於胞突接合上神經系統中的神經元,然後透過胞突接合處的裂縫處的神經傳導,可能刺激或抑制胞突接合後的神經,當一種潛在的作用足夠被刺激將被產生、引發膜去極(去偏極)和在細胞外與細胞內空間之間離子交換,離子導致一項大且可預測的改變在橫跨膜間的電壓.靜止的膜性電位是神經靜止的相對穩定狀態,正當這種絕對反抝期,在刺激後是一個間距(期間),在這個間隔當中神經可能不會興奮過大。在相對反抝期一條神經可能會被刺激過度,特定增加(提高) 的刺激,神經單位是足以表現在輸入的差異性,僅透過反應的比率,有髓(鞘)的纖維引導去極波比脫髓鞘纖維更加快速,主要是由於跳躍性的傳導。
Muscle is comprised of thick and thin myofilaments that slide across each other during contraction. Activation of a muscle fiber causes release of calcium into the environment of thick myofilaments, revealing the binding sites on the thin filaments that permit cross bridging from the thick filaments. Muscle shortening is the product of repeated contraction of the cross bridges. Slow twitch muscle fibers remain contracted longer than fast twitch fibers, with the former being involved in maintenance of posture and the latter in fine and rapid motor function. 肌肉是由厚與薄的肌原絲所組成,這些肌原絲透過其他在收縮之間的載物片。一種肌肉絲纖維的促動作用(刺激)引起鈣稀釋到厚的肌原絲環境(週邊),揭開連結在薄絲處,它允許交叉的架橋連結的從厚的絲。肌肉收縮是重複收縮, 交叉橋的產物。慢的牽搦肌肉纖維仍舊比快的纖維牽搦收縮更久,而快的纖維牽搦和前者的存在牽涉在姿勢的維持和後者較精緻及較快速的肌肉構造。
Muscle spindles provide feedback to the neuromotor system about muscle length, tension, motion, and position. Muscle spindles running parallel to intrafusal muscle fibers are sensors for muscle length, whereas golgi tendon organs sense muscle tension. Nuclear bag fibers convey information concerning acceleration and nuclear chain fibers respond o sustained lengthening. When a muscle is passively stretched, a segmental reflex is triggered. Extrafusal muscles paralleling the muscle spindles are activated and the muscle is shortened. Golgi tendon organs apparently respond to the tension of musculature during active contraction. 肌梭提供有關肌肉長度、張力、動作(運動)、姿勢(罷位)等運動神經系統的反饋作用。平行運作中的肌梭對肌梭內肌肉纖維是肌長的感應器,另一方面,哥耳奇氏腱器官感應肌肉張力,核袋纖維傳達有關加速的訊息,而核鍊纖維對支撐長度(拉長)起反應。當肌肉被動地被延展時,一個分段(分節)的反射(脊髓性反射)也被觸發,肌梭外平行對稱的肌梭被促進活動,同時肌肉被收縮(縮短)哥耳奇氏腱器官,在主動的(有作用的,有效的)肌收縮對肌肉張力明顯起反應。
Higher function of the brain defies a strict localization approach to functional organization. General regions, such as Wernicke’s area, can be ascribed broad function, and this view facilitated examination of brain function and dysfunction. Brain function may be classified into regions of primary, higher order, and association regions. Primary sensory and motor regions include the primary reception area for somatic sense, primary motor area, primary auditory cortex, and primary region of visual reception. Higher order areas of processing are apparently responsible for extracting features of the stimulus. Association areas are the regions of highest cognitive processing, integrating sensory information with memory. The prefrontal area appears to be involved in higher function related to motor output, while the temporal-occipital-parietal association is involved in spoken and written language function. The limbic association area integrates information relating to affect, motivation, and emotion. 腦部上的高度作用對功能上的組織有著嚴格區域定位法。一般區域，例如：魏尼凱氏區域能被描述為寬廣的作用。而且，此觀點有利於大腦功能的檢測以及功能障礙。大腦功能可區分為主要區域、高等次序及聯動區域。初期的感覺及運動區域包含對主要運動區域身體感覺的初期接收區域、主要聽覺皮質和首要的視覺接收區域。更高階的運作區域顯然負責萃取刺激物的特質。聯合運動區是認知處理的最高區域，連同記憶來整合感覺的資訊。额葉區域顯然是涉及有關運動輸出更高的作用，但顳的枕骨壁聯動是涉及口說與書寫語言的作用，邊緣的聯動區域整合關於情感的訊息。
Dysarthria is a speech disorder resulting from damage to the motor execution system of the central nervous system and resulting in muscular weakness and reduction in motor control. Flaccid dysarthria results from damage to LMN, whereas UMN lesions result in spastic dysarthria. Ataxic dysarthria arises from cerebellar damage. Hyperkinetic dysarthria is the result of damage to inhibitory proceses of the extraphraidal system, whereas hypokinetic dysarthria results from lesion to excitatory mechanisms. Apraxia arises from lesion to the regions associated with preparation and planning for the motor act, specifically the supramarginal gyrus of the parietal lobe, Broca’s area, and the SMA. Apraxia is a deficit in motor planning, existing without muscular weakness or paralysis. 構音困難肇因於中央神經系統中運動執行系統的損害，發音不良會導致肌肉無力且降低運動的控制。弛綏的發音不良起因於較低等的運動傷害， 然而較上層運動神經損害會引起痙攣性的構音困難 失調的發音不良由小腦的傷害引起。運動減退的構音困腦是在錐體外神經系統中抑制的過程所損害的結果，然而運動減退的發音不良卻由於對刺激機制的損害而產生的。失用症源自於對運動行為相關連的準備與籌劃區域的減退 ，特別是頂葉 布洛卡區域以及補充的運動區域緣上的腦回。失用症是一種運動規劃的缺失，存在於不是肌肉無力就是癱瘓麻痺。
The hemispheres of the brain display clear functional differences. Language and speech, brief duration stimuli, and detailed information are processed in the left hemisphere in most individuals. The right hemisphere appears to process information in a more holistic fashion, preferring spatial and tonal information. Lesions to Wernicke’s area in the dominant hemisphere result in a receptive language deficit with relatively intact speech fluency, whereas damage to Broca’s area results in loss of speech fluency. Damage to the arcuate fasciculus connecting these two regions will result in conduction aphasia, and damage to all of these regions will produce global deficit. Verbal dyspraxia may result from damage to Broca’s area, the supramarginal gyrus, supplementary motor area, frontal operculum, and insula. Right-hemisphere lesions often result in deficit in pragmatics, misinterpretation of information carried in the speech intonation, and communicative nuance. Frotnal lobe lesions often result in impaired judgment and failure to inhibit responses, whereas damage to the hippocampus will affect short-term memory. 大腦的兩個半球顯示清楚的功能上差異，在多數個體中的左半球負責著語言以及言談簡短期間的刺激及細節般的資料處理，右半球則明顯地在一種較多全體論的潮流去處理資訊，較優於空間及音樂的資訊，在顯性半球魏尼凱區域的損害導致於語言接收的不足，隨著相對完整的流利言談，雖然布洛卡區域的損害會引發言談流利的喪失，有關於這兩個區域對弓狀的肌束(大腦上縱束)的損害將導致失語症，同時對這區域的所有損害也將產生球體的不足。口語(用言語表現的)運用障礙可能是由布洛卡區域損害發生造成的，布洛卡區域是指緣上的腦回，補充性的運動區域、額蓋及腦島。右半球損害時常導致語用的不足，隨著言談的語調對資料的誤譯及溝通性的意義上的細微差異，額葉損害經常導致判斷不足及無法抑制反應，然而海馬的損害將影響短期記憶。
Movement is initiated at the motor strip, but there is a great deal of planning that occurs prior to that point. The premotor regions, including Broca’s area, are involved in planning for the motor act, and project that plan to the motor strip. The prefrontal association area also provides input to the motor strip concerning higher cognitive elements of the speech act, and the lowest levels of information (information about muscle stretch and tension) are also fed to the motor strip. 雖然在運動條痕處啟動著動作，卻有許多大量的規劃發生優先於那點條痕，這個運動的前區域加上布洛卡區域都為了運動行動一起參與規劃，對運動條痕也使得計劃具體化，額葉聯合作用區域也提供了有關於對言談行為及最低階的資訊(這些資訊都是關於肌肉延展及張力)當中較高等的認知元素對運動條痕的輸入，也都給行動條痕提供這些資訊。
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