Molotchnikoff S, Morin C, Lachapelle P
Université de Montréal, Département des Sciences Biologiques, Québec, Canada.
Exp Brain Res. 1992;89(3):531-9. doi: 10.1007/BF00229878.
The described investigations study the influence of additional targets located well outside the classical receptive field on responses to motion of cortical cells in rabbits. Animals are anesthetized and prepared for acute single cells recordings in a conventional manner. The interactions between remote targets and central stimuli are abolished with microinjections of lidocaine hydrochloride or GABA at the site excited by remote stimuli. Results show that responses to motion of cortical cells are particularly sensitive to these manipulations. Although supplementary targets fail to influence spontaneous activity of all cells, they do influence responses to motion. Overall, the directionality indices (DI) declined. (53 to 45.) This decline may express itself either by a decrease of responses in the preferred direction or an enhancement of responses in the non-preferred direction or both. By contrast, responses to stationary stimuli are unaffected by additional targets in the visual field. Globally, cells whose directionality index was superior to 50% were significantly more affected then cells whose DI was less than 50%. This result suggests that similarly to cats, the directionality of cells in the striate cortex rests on a very fragile convergence of excitatory and inhibitory influences.
上述研究探讨了位于经典感受野之外的额外靶点对兔皮层细胞运动反应的影响。动物经麻醉后，以常规方式准备进行急性单细胞记录。通过在由远程刺激激发的部位微量注射盐酸利多卡因或γ-氨基丁酸（GABA），消除远程靶点与中央刺激之间的相互作用。结果表明，皮层细胞对运动的反应对这些操作特别敏感。虽然额外靶点未能影响所有细胞的自发活动，但它们确实影响对运动的反应。总体而言，方向性指数（DI）下降（从53降至45）。这种下降可能表现为在偏好方向上反应的减少，或者在非偏好方向上反应的增强，或者两者兼而有之。相比之下，对静止刺激的反应不受视野中额外靶点的影响。总体而言，方向性指数高于50%的细胞比方向性指数低于50%的细胞受到的影响明显更大。这一结果表明，与猫类似，纹状皮层中细胞的方向性依赖于兴奋性和抑制性影响的非常脆弱的汇聚。
