Nishitani N, Ikeda A, Nagamine T, Honda M, Mikuni N, Taki W, Kimura J, Shibasaki H
Department of Brain Pathophysiology, Kyoto University Faculty of Medicine, Japan.
Brain. 1999 Apr;122 ( Pt 4):687-707. doi: 10.1093/brain/122.4.687.
To clarify the relationship between the hippocampus and the event-related responses in auditory information processing, we recorded event-related potentials (ERPs) and event-related magnetic fields (ERFs) associated with the auditory oddball paradigm in 12 patients with temporal lobe epilepsy before and after surgical treatment, and in eight age-matched healthy volunteers. Lesions in the patients were hippocampal sclerosis (8), cyst (2), cavernoma (1) and calcified arteriovenous malformation (1), all in the unilateral temporal lobe. Standard temporal lobectomy (8), selective amygdalohippocampectomy (2), selective hippocampectomy (1) and inferior lateral temporal resection (1) were carried out. ERPs were recorded in nine patients before surgery, in all 12 patients after surgery, and in all normal subjects. P300 was maximal at Pz in the patients both before and after surgery, and in normal subjects. The peak latency and amplitude of P300 measured at Pz in the patients either before or after surgery did not differ significantly from those in normal subjects. After surgery, only the amplitude of P300 over the anterior and mid-temporal area on the resected side was attenuated, while it was symmetric before surgery regardless of the side of epileptogenic focus. ERFs were recorded in three patients before surgery and in six normal subjects by using a whole-head neuromagnetometer. ERFs in response to the target stimuli at a latency of approximately 400 ms were recognized at the anterior, middle and posterior lateral channels on each hemisphere (M400). The latency and dipole moments for M400 did not differ significantly between the patients before surgery and the normal subjects. As a result of analysis using the time-varying multidipole model, three dipoles for M400 were estimated in two patients in whom ERFs were available before surgery for the analysis, and in normal subjects: mesial temporal area, superior temporal area and inferior parietal area on each hemisphere. After surgery, in four out of six patients in whom ERFs were recordable, M400 at the anterior temporal channels on the resected side disappeared, and the activity in the affected mesial temporal area was lost. In one patient who underwent inferior lateral temporal resection, M400 waveforms and its sources were preserved in all regions. There were no significant differences in the latency and dipole moments of the unaffected source of M400 before versus after surgery. These results suggest that the hippocampus contributes to the scalp-recorded P300 only at the corresponding anterior temporal region, and does not influence its general waveform and predominant distribution over the scalp.
为阐明海马体与听觉信息处理中事件相关反应之间的关系，我们记录了12例颞叶癫痫患者手术治疗前后以及8名年龄匹配的健康志愿者在听觉奇偶数范式下的事件相关电位（ERP）和事件相关磁场（ERF）。患者的病变包括海马硬化（8例）、囊肿（2例）、海绵状血管瘤（1例）和钙化动静脉畸形（1例），均位于单侧颞叶。实施了标准颞叶切除术（8例）、选择性杏仁核海马切除术（2例）、选择性海马切除术（1例）和颞叶下外侧切除术（1例）。术前对9例患者、术后对所有12例患者以及所有正常受试者进行了ERP记录。患者术前和术后以及正常受试者的P300在头顶中央（Pz）处最大。术前和术后患者在Pz处测量的P300的峰值潜伏期和波幅与正常受试者相比无显著差异。术后，仅切除侧颞叶前部和中部区域的P300波幅衰减，而术前无论致痫灶位于哪一侧，其两侧均对称。术前对3例患者和6例正常受试者使用全头式神经磁强计记录了ERF。在每个半球的前、中、后外侧通道均识别出了潜伏期约为400 ms的对目标刺激的ERF（M400）。术前患者与正常受试者的M400潜伏期和偶极矩无显著差异。通过时变多偶极模型分析，在术前可获得ERF用于分析的2例患者以及正常受试者中，估计M400有三个偶极：每个半球的颞叶内侧区域、颞叶上区域和顶叶下区域。术后，在可记录ERF的6例患者中的4例中，切除侧颞叶前部通道的M400消失，患侧颞叶内侧区域的活动丧失。在1例接受颞叶下外侧切除术的患者中，所有区域的M400波形及其来源均得以保留。手术前后M400未受影响的来源的潜伏期和偶极矩无显著差异。这些结果表明，海马体仅在相应的颞叶前部区域对头皮记录的P300有贡献，而不影响其总体波形和在头皮上的主要分布。
