Patel S N, Stewart M G
Brain Research Group, Open University, Milton Keynes, U.K.
Brain Res. 1988 May 24;449(1-2):34-46. doi: 10.1016/0006-8993(88)91021-9.
One-day-old chicks spontaneously peck at a shiny chrome bead. If the bead is coated with methylanthranilate, a bitter tasting substance (M-chicks), they peck once and avoid a similar bead subsequently. Control chicks peck, and continue pecking at a bead dipped in water (W-chicks). Twenty-five hours after this one-trial passive avoidance training the brains were fixed and Golgi-impregnated. A class of large, multipolar, projection neurons from the intermediate medial hyperstriatum ventrale (IMHV) of both hemispheres from M- and W-chicks were examined for changes in their spine density and spine shape. An estimate of the true spine number was obtained using the correction formula of Feldman and Peters. M-chicks showed highly significant increases (P less than 0.0001) in spine density of between 89-113% in the left hemisphere, and 37-69% in the right, compared with W-chicks. There was a significant hemispheric asymmetry in W-chicks: the right hemisphere had approximately 47% more spines per micron than the left, and this difference was abolished after training. Following passive avoidance training, significant increases in spine head diameter (by approximately 9%) and decreases in spine stem length (by approximately 17%), with no significant alterations in overall spine length, were observed in the left hemisphere. The mean dendrite lengths were not significantly changed after training, but an asymmetry of this measure in W-chicks (left greater than right) was present in dendrite orders 2 (P less than 0.01) and 3 (P less than 0.02). These results show that spine densities can increase rapidly (within 25 h) following a one-trial passive avoidance training task and that spine shape changes can be found on the same dendrites which also show changes in spine number. The data support the view that dendritic spines are involved in memory formation processes.
一日龄雏鸡会自发啄食闪亮的镀铬珠子。如果珠子涂有邻氨基苯甲酸甲酯，一种苦味物质（M组雏鸡），它们啄一次后就会避开类似的珠子。对照雏鸡会啄食，并继续啄食蘸过水的珠子（W组雏鸡）。在这种单次被动回避训练25小时后，将大脑固定并进行高尔基染色。对来自M组和W组雏鸡两个半球的中间内侧腹侧超纹状体（IMHV）中的一类大型多极投射神经元进行检查，观察其棘突密度和棘突形状的变化。使用费尔德曼和彼得斯的校正公式获得真实棘突数量的估计值。与W组雏鸡相比，M组雏鸡左半球的棘突密度显著增加（P小于0.0001），增幅在89%至113%之间，右半球的增幅在37%至69%之间。W组雏鸡存在显著的半球不对称性：右半球每微米的棘突比左半球多约47%，训练后这种差异消失。被动回避训练后，左半球观察到棘突头部直径显著增加（约9%），棘突干长度显著减少（约17%），而棘突总长度无显著变化。训练后平均树突长度无显著变化，但W组雏鸡在树突二级（P小于0.01）和三级（P小于0.02）存在这种测量的不对称性（左大于右）。这些结果表明，单次被动回避训练任务后棘突密度可迅速增加（25小时内），并且在同一树突上可以发现棘突形状的变化，同时棘突数量也有变化。数据支持树突棘参与记忆形成过程的观点。
