Collins D R, Pelletier J G, Paré D
Laboratoire de Neurophysiologie, Département de Physiologie, Faculté de Médecine, Université Laval, Quebec, Quebec G1K 7P4, Canada.
J Neurophysiol. 2001 Apr;85(4):1661-72. doi: 10.1152/jn.2001.85.4.1661.
Most lesion studies emphasize the distinct contributions of the amygdala and perirhinal cortex to memory. Yet, the presence of strong reciprocal excitatory projections between these two structures suggests that they are functionally coupled. To gain some insight into this issue, the present study examined whether the close anatomical ties existing between perirhinal and lateral amygdala (LA) neurons are expressed in their spontaneous activity. To this end, multiple simultaneous recordings of single unit discharges and local field potentials were performed in the LA and perirhinal cortex in ketamine-xylazine anesthetized cats. The perirhinal cortex and LA exhibited a similar pattern of spontaneous activity. Recordings at both sites were dominated by a slow focal oscillation at 1 Hz onto which was superimposed a faster rhythm (approximately 30 Hz) whose amplitude fluctuated cyclically. Computing crosscorrelograms between focal waves recorded simultaneously in the perirhinal cortex and LA revealed a close relationship between their spontaneous activity. Even when recording sites were separated by as much as 8 mm, the slow focal oscillation remained highly correlated (r > or = 0.7). In contrast, the correlation between fast oscillations was usually lower (r approximately 0.3). Perievent histograms of neuronal discharges revealed that the firing probability of most LA and perirhinal neurons increased during the depth-negative component of the slow oscillation. In addition, respectively, 47 and 64% of LA and perirhinal neurons exhibited a significant modulation of firing probability in relation to the fast oscillations. Finally, crosscorrelating unit discharges simultaneously recorded in the LA and perirhinal cortex confirmed the presence of phase-related oscillatory events in both structures. In summary, our results suggest that the interconnections existing between the perirhinal cortex and LA can support the genesis of coherent neuronal activities at various frequencies. These results imply that cooperative interactions must be taking place between these structures.
大多数损伤研究都强调了杏仁核和嗅周皮质对记忆的不同贡献。然而，这两个结构之间存在强烈的相互兴奋性投射，这表明它们在功能上是耦合的。为了深入了解这个问题，本研究考察了嗅周皮质和外侧杏仁核（LA）神经元之间紧密的解剖联系是否在它们的自发活动中表现出来。为此，在氯胺酮-赛拉嗪麻醉的猫的LA和嗅周皮质中进行了单单位放电和局部场电位的多通道同步记录。嗅周皮质和LA表现出相似的自发活动模式。两个部位的记录都以1Hz的缓慢局灶性振荡为主，其上叠加有更快的节律（约30Hz），其振幅呈周期性波动。计算在嗅周皮质和LA同时记录的局灶波之间的互相关图，揭示了它们自发活动之间的密切关系。即使记录部位相隔多达8mm，缓慢的局灶性振荡仍高度相关（r≥0.7）。相比之下，快速振荡之间的相关性通常较低（r约为0.3）。神经元放电的事件周围直方图显示，大多数LA和嗅周神经元的放电概率在缓慢振荡的深度负成分期间增加。此外，分别有47%和64%的LA和嗅周神经元表现出与快速振荡相关的放电概率的显著调制。最后，对在LA和嗅周皮质同时记录的单位放电进行互相关分析，证实了两个结构中都存在与相位相关的振荡事件。总之，我们的结果表明，嗅周皮质和LA之间的互连可以支持各种频率下相干神经元活动的产生。这些结果意味着这些结构之间一定发生了协同相互作用。
