Goodridge J P, Taube J S
Department of Psychology, Dartmouth College, Hanover, New Hampshire 03755, USA.
J Neurosci. 1997 Dec 1;17(23):9315-30. doi: 10.1523/JNEUROSCI.17-23-09315.1997.
Previous research has identified neurons in the postsubiculum (PoS) and anterior dorsal thalamic nucleus (AD) of the rat that discharge as a function of the animal's head direction. In addition, anatomical studies have shown that the AD and PoS are reciprocally connected with one another. The current study examined whether head direction (HD) cells in each of the two areas is dependent on input from the other structure. After both electrolytic or neurotoxic lesions of the AD, no cells were identified with direction-specific discharge in the PoS. In contrast, AD HD cell activity was still present after neurotoxic lesions to the PoS. However, AD HD cells in PoS-lesioned rats exhibited three important differences compared with AD HD cells in intact animals: (1) their directional firing range was significantly larger, (2) their firing predicted the animal's future head direction by a larger amount, and (3) their preferred firing direction was substantially less influenced by a prominent visual landmark within the recording environment. These results indicate that information critical for HD cell activity is conveyed in both directions between the AD and the PoS; whereas the AD is necessary for the presence of HD cell activity in the PoS, the PoS appears important in allowing visual landmarks to exert control over the preferred firing direction of AD HD cells. These findings have implications for several computational models that propose to account for the generation of the HD cell signal.
先前的研究已在大鼠的后下托（PoS）和丘脑前背核（AD）中识别出根据动物头部方向放电的神经元。此外，解剖学研究表明，AD和PoS相互连接。当前的研究考察了这两个区域中每个区域的头部方向（HD）细胞是否依赖于来自另一个结构的输入。在对AD进行电解或神经毒性损伤后，在PoS中未识别出具有方向特异性放电的细胞。相比之下，在对PoS进行神经毒性损伤后，AD HD细胞的活动仍然存在。然而，与完整动物中的AD HD细胞相比，PoS损伤大鼠中的AD HD细胞表现出三个重要差异：（1）它们的定向放电范围显著更大，（2）它们的放电对动物未来头部方向的预测量更大，（3）它们的偏好放电方向受记录环境中突出视觉地标影响的程度明显更小。这些结果表明，对HD细胞活动至关重要的信息在AD和PoS之间双向传递；虽然PoS中HD细胞活动的存在需要AD，但PoS似乎在使视觉地标对AD HD细胞的偏好放电方向施加控制方面很重要。这些发现对几种试图解释HD细胞信号产生的计算模型具有启示意义。
