Department of Psychology, University of Otago, Dunedin, New Zealand.
Hippocampus. 2010 May;20(5):573-83. doi: 10.1002/hipo.20666.
Hippocampal place cells have the interesting property of increasing their firing rate when a freely moving animal increases its running speed through the cell's place field. A previous study from this laboratory showed that this movement-related firing property is disrupted by lesions of the perirhinal cortex (PrhC). It is possible, therefore, that PrhC lesions disrupt speed-modulated sensory information such as optic flow or motor efferent or proprioceptive input that might be available to the hippocampus from the PrhC. To test this hypothesis, rats with single unit recording electrodes implanted in the CA1 region of the hippocampus received different levels of optic flow stimulation in both a freely moving and a passive movement condition. The effects of PrhC lesions were also tested. Although increasing the amount of optic flow information available decreased place field size, it had no discernable effect on the movement-firing rate relationship in the place cells of control animals run in the free-movement condition. In lesioned animals the relationship was disrupted, replicating our previous results. In the passive movement condition many place cells stopped firing. In those cells that did fire, however, the movement-firing rate relationship was no longer evident. These data indicate that the movement-firing rate relationship is not driven by vestibular or optic flow cues, but rather depends on either motor efferent or proprioceptive input, or that it results from some other form of input that may be modulated by self-motion, such as from the vibrissae.
海马体位置细胞有一个有趣的特性，当自由移动的动物通过其位置区域时增加奔跑速度，其放电频率会增加。本实验室的一项先前研究表明，这种与运动相关的放电特性会被边缘区皮层（PrhC）的损伤破坏。因此，PrhC 损伤可能破坏了可能从 PrhC 传递到海马体的速度调节感觉信息，如光流或运动传出或本体感受输入。为了验证这一假设，在海马体 CA1 区植入单个单元记录电极的大鼠在自由运动和被动运动条件下接受不同水平的光流刺激。还测试了 PrhC 损伤的影响。尽管增加了光流信息的数量，减小了位置区域的大小，但它对控制动物在自由运动条件下的位置细胞的运动放电率关系没有明显影响。在受损动物中，这种关系被破坏，复制了我们之前的结果。在被动运动条件下，许多位置细胞停止放电。然而，在那些仍在放电的细胞中，运动放电率关系不再明显。这些数据表明，运动放电率关系不是由前庭或光流线索驱动的，而是依赖于运动传出或本体感受输入，或者它是由其他可能受到自身运动调节的输入形式引起的，例如来自触须。
