Shaw N A
Department of Physiology, School of Medicine, University of Auckland, New Zealand.
J Neurosci Methods. 1992 Sep;44(2-3):233-40. doi: 10.1016/0165-0270(92)90015-6.
Flash visual evoked potentials (FVEPs) were recorded from the rat in order to determine the effects of low-pass filtering on the wave form. The low-frequency (high pass) filter remained fixed at 3.2 Hz while the setting of the high-frequency (low-pass) filter was progressively raised from 32 Hz to 3.2 kHz. The amplitude of the primary cortical potential (P30) steadily increased while its latency decreased until asymptotic values were recorded with a low-pass cut-off of 320 Hz. Thereafter, there was little additional change in wave form. It is concluded that a bandpass of 3.2-320 Hz is optimal to record the primary cortical response of the FVEP, and this is consistent with the theory that the P30 potential is generated by comparatively slow post-synaptic activity. In a second experiment the effects of low-pass filtering were examined on the later and more labile secondary components of the FVEP wave form. These were found to be less responsive to low-pass filtering than the early components and assumed a near optimal configuration when the high-frequency cut-off was raised to 80 Hz. The high-frequency filter setting which is most appropriate to record the primary component of the FVEP therefore appears to be more than adequate also to record the secondary responses. It is also shown that the same principles of low-pass filtering on the FVEP will apply irrespective of whether the subject is awake or anaesthetised.
为了确定低通滤波对波形的影响，从大鼠记录了闪光视觉诱发电位（FVEPs）。低频（高通）滤波器固定在3.2Hz，而高频（低通）滤波器的设置从32Hz逐渐提高到3.2kHz。初级皮层电位（P30）的幅度稳步增加，而其潜伏期缩短，直到在320Hz的低通截止频率下记录到渐近值。此后，波形几乎没有进一步变化。得出的结论是，3.2 - 320Hz的带通对于记录FVEP的初级皮层反应是最佳的，这与P30电位由相对缓慢的突触后活动产生的理论一致。在第二个实验中，研究了低通滤波对FVEP波形中较晚出现且更不稳定的次级成分的影响。发现这些成分对低通滤波的反应不如早期成分，并且当高频截止频率提高到80Hz时呈现出接近最佳的形态。因此，最适合记录FVEP初级成分的高频滤波器设置似乎也足以记录次级反应。还表明，无论受试者是清醒还是麻醉，FVEP上低通滤波的相同原则都适用。
