Hyman James M, Zilli Eric A, Paley Amanda M, Hasselmo Michael E
Center for Memory and Brain, Department of Psychology, Boston University, Boston, MA 02215, USA.
Hippocampus. 2005;15(6):739-49. doi: 10.1002/hipo.20106.
Both the hippocampus and the medial prefrontal cortex are essential for successful performance in learning- and memory-related tasks. Within the hippocampus the theta rhythm plays an integral role in the timing of action potentials of hippocampal neurons responding to elements of any given task. Medial prefrontal cortex (mPFC) neurons display firing rate changes to specific facets of behavioral tasks (Jung et al., 1998. Cereb Cortex 8:437--450). We recorded units in the mPFC and field potentials in the hippocampus to determine whether behaviorally correlated mPFC cells fired with phase relationships to the hippocampal theta rhythm. In two different behavioral tasks (running a linear track and foraging in two distinct environments) we found mPFC cells that alternated between theta entrained firing and nonphasic firing depending on the ongoing behavior, while other cells were modulated during all conditions in both tasks. The majority of the mPFC cells with a significant correlation of firing rate changes with behavior were entrained to hippocampal theta. Cells that fired to specific events during only one direction of running were predisposed to theta modulation only in that direction. mPFC neurons have the capability to respond to behaviorally relevant elements by dynamically alternating between hippocampal theta entrained and nonphasic firing.
海马体和内侧前额叶皮质对于在学习和记忆相关任务中的成功表现都至关重要。在海马体内，θ节律在对任何给定任务的元素做出反应的海马神经元动作电位的定时中起着不可或缺的作用。内侧前额叶皮质（mPFC）神经元对行为任务的特定方面表现出放电率变化（Jung等人，1998年。《大脑皮层》8：437 - 450）。我们记录了mPFC中的神经元单位和海马体中的场电位，以确定与行为相关的mPFC细胞是否与海马体θ节律呈相位关系放电。在两项不同的行为任务（在直线轨道上奔跑和在两个不同环境中觅食）中，我们发现mPFC细胞根据当前行为在θ节律夹带放电和非相位放电之间交替，而其他细胞在两项任务的所有条件下都受到调制。大多数放电率变化与行为有显著相关性的mPFC细胞被夹带至海马体θ节律。仅在一个奔跑方向上对特定事件放电的细胞仅在该方向上倾向于θ调制。mPFC神经元有能力通过在海马体θ节律夹带放电和非相位放电之间动态交替来对行为相关元素做出反应。
