Browning Philip G F, Gaffan David
Department of Experimental Psychology, Oxford University, Oxford OX1 3UD, United Kingdom.
J Neurosci. 2008 Apr 9;28(15):3934-40. doi: 10.1523/JNEUROSCI.0633-08.2008.
The frontal cortex and inferior temporal cortex are strongly functionally interconnected. Previous experiments on prefrontal function in monkeys have shown that a disconnection of prefrontal cortex from inferior temporal cortex impairs a variety of complex visual learning tasks but leaves simple concurrent object-reward association learning intact. We investigated the possibility that temporal components of visual learning tasks determine the sensitivity of those tasks to prefrontal-temporal disconnection by adding specific temporal components to the concurrent object-reward association learning task. Monkeys with crossed unilateral lesions of prefrontal cortex and inferior temporal cortex were impaired compared with unoperated controls at associating two-item sequences of visual objects with reward. The impairment was specific to the learning of visual sequences, because disconnection was without effect on object-reward association learning for an equivalent delayed reward. This result was replicated in monkeys with transection of the uncinate fascicle, thus determining the anatomical specificity of the dissociation. Previous behavioral results suggest that monkeys represent the two-item serial compound stimuli in a configural manner, similar to the way monkeys represent simultaneously presented compound stimuli. The representation of simultaneously presented configural stimuli depends on the perirhinal cortex. The present experiments show that the representation of serially presented compound stimuli depends on the interaction of prefrontal cortex and inferior temporal cortex. We suggest that prefrontal-temporal disconnection impairs a wide variety of learning tasks because in those tasks monkeys lay down similar temporally complex representations.
额叶皮质和颞下回皮质在功能上紧密相连。先前对猴子前额叶功能的实验表明，前额叶皮质与颞下回皮质的联系中断会损害各种复杂的视觉学习任务，但简单的同时性物体 - 奖励关联学习则不受影响。我们通过在同时性物体 - 奖励关联学习任务中添加特定的时间成分，研究视觉学习任务的时间成分是否决定了这些任务对前额叶 - 颞叶联系中断的敏感性。与未手术的对照组相比，前额叶皮质和颞下回皮质单侧交叉损伤的猴子在将视觉物体的两项序列与奖励进行关联时受到了损害。这种损害特定于视觉序列的学习，因为联系中断对等效延迟奖励的物体 - 奖励关联学习没有影响。在钩状束横断的猴子中重复了这一结果，从而确定了解离的解剖学特异性。先前的行为结果表明，猴子以构型方式表征两项系列复合刺激，类似于猴子表征同时呈现的复合刺激的方式。同时呈现的构型刺激的表征依赖于嗅周皮质。目前的实验表明，序列呈现的复合刺激的表征依赖于前额叶皮质和颞下回皮质的相互作用。我们认为，前额叶 - 颞叶联系中断会损害多种学习任务，因为在这些任务中猴子形成了类似的时间上复杂的表征。
