Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark, New Jersey 07102, USA.
J Neurosci. 2010 Feb 3;30(5):1777-87. doi: 10.1523/JNEUROSCI.4681-09.2010.
Although anatomical, lesion, and imaging studies of the hippocampus indicate qualitatively different information processing along its septo-temporal axis, physiological mechanisms supporting such distinction are missing. We found fundamental differences between the dorsal (dCA3) and the ventral-most parts (vCA3) of the hippocampus in both environmental representation and temporal dynamics. Discrete place fields of dCA3 neurons evenly covered all parts of the testing environments. In contrast, vCA3 neurons (1) rarely showed continuous two-dimensional place fields, (2) differentiated open and closed arms of a radial maze, and (3) discharged similar firing patterns with respect to the goals, both on multiple arms of a radial maze and during opposite journeys in a zigzag maze. In addition, theta power and the fraction of theta-rhythmic neurons were substantially reduced in the ventral compared with dorsal hippocampus. We hypothesize that the spatial representation in the septo-temporal axis of the hippocampus is progressively decreased. This change is paralleled with a reduction of theta rhythm and an increased representation of nonspatial information.
尽管对海马体的解剖、病变和影像学研究表明其在隔颞轴上具有定性不同的信息处理方式，但支持这种区别的生理机制尚不清楚。我们发现，在环境表征和时间动态方面，海马体的背侧（dCA3）和最腹侧部分（vCA3）之间存在根本差异。dCA3 神经元的离散位置场均匀覆盖了测试环境的所有部分。相比之下，vCA3 神经元（1）很少表现出连续的二维位置场，（2）区分放射状迷宫的开臂和闭臂，（3）在放射状迷宫的多个臂上以及在之字形迷宫的相反行程中，对目标表现出相似的放电模式。此外，与背侧海马体相比，腹侧海马体的θ 功率和θ 节律神经元的分数明显降低。我们假设海马体在隔颞轴上的空间表示逐渐减少。这种变化与θ 节律的减少和非空间信息的增加表示相平行。
