頭頂連合野の神経解剖学

Neuroanatomy of the Parietal Association Areas

頭頂連合野は頭頂葉のうち外側面の上・下頭頂小葉と内側面の楔前部，ならびに頭頂間溝，頭頂後頭溝，月状溝内部の皮質を占める。頭頂連合野は体性感覚，視覚，聴覚，平衡感覚などの入力を処理し，空間認知に関わるとともに眼球運動や四肢運動の制御を担う。体性感覚情報は中心後回に位置する一次体性感覚野や二次体性感覚野からまずは上頭頂小葉に送られて，さらに下頭頂小葉に至る。視覚情報はいわゆる視覚の背側経路をつくって，主に下頭頂小葉，頭頂間溝内部，ならびに楔前部に至る。聴覚は一次聴覚野から後方の周辺皮質経由で下頭頂小葉後部に入る。頭頂間溝内部の皮質は運動前野，前頭眼野，前頭前野に投射して，主に上肢と眼球の運動制御をつかさどるとともに空間情報のワーキングメモリに関わる。下頭頂小葉後部と楔前部の皮質は直接に，あるいは帯状回後部を介して間接に，海馬傍回皮質と嗅内野に投射し，海馬における長期記憶形成に関与する。

Abstract

The parietal association cortex comprises the superior and inferior parietal lobules, the precuneus and the cortices in the intraparietal, parietooccipital and lunate sulci. By processing somatic, visual, acoustic and vestibular sensory information, the parietal association cortex plays a pivotal role in spatial cognition and motor control of the eyes and the extremities. Sensory information from the primary and secondary somatosensory areas enters the superior parietal lobule and is transferred to the inferior parietal lobule. Visual information is processed through the dorsal visual pathway and it reaches the inferior parietal lobule, the intraparietal sulcus and the precuneus. Acoustic information is transferred posteriorly from the primary acoustic area, and it reaches the posterior region of the inferior parietal lobule. The areas in the intraparietal sulcus project to the premotor area, the frontal eye fields, and the prefrontal area. These areas are involved in the control of ocular movements, reaching and grasping of the upper extremities, and spatial working memory. The posterior region of the inferior parietal lobule and the precuneus both project either directly, or indirectly via the posterior cingulate gyrus, to the parahippocampal and entorhinal cortices. Both these areas are strongly associated with hippocampal functions for long-term memory formation.