大鼠初級體感覺皮質與初級運動皮質於感覺傳遞與執行動作過程之神經元活性比較

Abstract

初級體感覺皮質(Primary somatosensory cortex, SI)和初級運動皮質(Primary motor cortex, MI)分別為身體感覺和主動運動之核心，在麻醉狀態中具有functional segregation的特性。本研究為探討SI和MI在清醒動物中是否維持分工的特性，以多頻道微電極同時記錄同一隻大鼠的SI及MI，比較兩區的神經元在前掌受到輕觸(風吹刺激)和傷害性(雷射熱)刺激時的反應，以及在執行主動運動(步行和抓取)時的活動變化。麻醉時SI對於感覺刺激產生明顯的興奮，MI則缺乏反應，然而在清醒狀態中兩者皆對感覺刺激出現興奮，反應趨於相似；在主動運動方面，SI和MI神經元的活動皆與動作過程相關。這些證據顯示，清醒大鼠的SI及MI互有參與感覺認知和自主運動的控制，而且兩者的功能息息相關，其分工情形與麻醉狀態不盡相同。

Primary somatosensory cortex (SI) and primary motor cortex (MI) have been thought of as the most critical centers for perception and voluntary motor control respectively. To explore the hypothesis of segregation of functions in conscious animal, we recorded directly multiple single-units in the forelimb region of SI and MI in the same rat, SI and MI neuronal activities were compared during tactile (air puffs) and noxious (laser heat) stimulation of the glabrous skin of the forepaw, and during voluntary movement of the forelimb (walking and grasping). Our data showed that SI neurons had brisk response to sensory stimuli comparing with MI under anesthetized status, while these two areas tends to share similar response in the conscious state. Also, both SI and MI had significant correlative neuronal activities in the process of voluntary movement. These data indicate that MI and SI have well-defined functional segregation under anesthesia, yet work closely together in sensorimotor integration in the conscious state.