Galletti C, Fattori P, Kutz D F, Gamberini M
Dipartimento di fisiologia umana e generale, Universita' di Bologna, Italy.
Eur J Neurosci. 1999 Feb;11(2):575-82. doi: 10.1046/j.1460-9568.1999.00467.x.
The brain location, extent and functional organization of the cortical visual area V6A was investigated in macaque monkeys by using single cell recording techniques in awake, behaving animals. Six hemispheres of four animals were studied. Area V6A occupies a horseshoe-like region of cortex in the caudalmost part of the superior parietal lobule. It extends from the medial surface of the brain, through the anterior bank of the parieto-occipital sulcus, up to the most lateral part of the fundus of the same sulcus. Area V6A borders on areas V6 ventrally, PEc dorsally, PGm medially and MIP laterally. Of 1348 neurons recorded in V6A, 61% were visual and 39% non-visual in nature. The visual neurons were particularly sensitive to orientation and direction of movement of visual stimuli. The inferior contralateral quadrant was the most represented one. Visual receptive fields were also found in the inferior ipsilateral quadrant and in the upper visual field. Receptive fields were on average smaller in the lower visual field than in the upper one. Both central and peripheral parts of the visual field were represented. Large parts of the visual field were represented in small regions of area V6A, and the same regions of the visual field were re-represented many times in different parts of this area, without any apparent topographical order. The only reliable sign of retinotopic organization was the predominance of central representation dorsally and far periphery ventrally. The functional organization of area V6A is discussed in the view that this area could be involved in the control of reaching out and grasping objects.
通过在清醒、行为活动的猕猴中使用单细胞记录技术，对皮质视觉区V6A的脑定位、范围和功能组织进行了研究。研究了4只动物的6个半球。V6A区位于顶上小叶最尾端部分的皮质马蹄形区域。它从脑的内表面延伸，穿过顶枕沟的前缘，直至同一脑沟底部的最外侧部分。V6A区腹侧与V6区相邻，背侧与PEc区相邻，内侧与PGm区相邻，外侧与MIP区相邻。在V6A区记录的1348个神经元中，61%本质上是视觉神经元，39%是非视觉神经元。视觉神经元对视觉刺激的方向和运动方向特别敏感。对侧下象限是最具代表性的区域。在同侧下象限和上视野中也发现了视觉感受野。下视野中的感受野平均比上视野中的小。视野的中央和周边部分均有代表。视野的大部分在V6A区的小区域中得到代表，并且视野的相同区域在该区域的不同部分多次重复代表，没有任何明显的拓扑顺序。视网膜拓扑组织的唯一可靠标志是中央代表在背侧占优势，远周边在腹侧占优势。鉴于该区域可能参与伸手和抓握物体的控制，对V6A区的功能组织进行了讨论。
