Pineda J A, Holmes T C, Foote S L
Department of Cognitive Science, University of California, San Diego, La Jolla 92093.
Electroencephalogr Clin Neurophysiol. 1991 Jun;78(6):456-65. doi: 10.1016/0013-4694(91)90063-a.
In human, the amplitudes of specific event-related potential (ERP) components can increase or decrease in response to increasing stimulus intensity depending on the location of the recording site. Large increases characterize components presumably generated by modality-specific sites, while smaller increases or even decreases are associated with those originating in associational areas. Comparable data from non-human primates, which would permit invasive studies of the neural substrates underlying these intensity-amplitude differences, are limited. To more fully characterize these relationships, auditory ERPs were recorded from chronically implanted epidural electrodes in 5 squirrel monkeys (Saimiri sciureus) in response to tones (500 Hz, 300 msec duration) of varying intensities (50, 60, 70, 80 dB SPL). Squirrel monkey ERPs recorded at Fz exhibited 3 peaks during the 200 msec post-stimulus interval. These peaks included a positivity (P1), followed by a negativity (N1), and then another positivity (P2). At posterior sites, the frontal P1-N1 configuration was recorded as an N1-P1 complex. At these sites, a small negativity (N2) preceded the last positive peak (P2). Changes in polarity were independent of reference site and posterior N1-P1 peaks exhibited latencies similar to those of the frontal P1-N1 components. Amplitudes at Fz, Cz, and Pz increased substantially with increasing stimulus intensity ('augmenting'). In contrast, only small increases or even decreases in amplitude ('reducing') were evident at T3 and T4. On the other hand, peak latencies decreased with higher stimulus intensities at most sites. The site-specific amplitude responses exhibited considerable temporal stability. In one subject, for example, similar 'augmenting' profiles were recorded at Fz in 8 sessions over a 6-month period. The topography of monkey intensity-amplitude response profiles, their temporal stability, and peak latency shifts resemble observations made in humans. The data show that 'augmenting' characterizes monkey vertex potentials, which, like the analogous human potentials, may originate in primary auditory cortex. In contrast, potentials recorded over temporal cortex, which may originate in auditory association cortex, exhibit 'reducing.' Thus, the data support the hypothesis that differences in amplitude with increasing intensity may reflect differences in cortical origin.
在人类中，特定事件相关电位（ERP）成分的波幅会随着刺激强度的增加而增加或减少，这取决于记录部位的位置。波幅大幅增加是由特定感觉模态部位产生的成分的特征，而较小的增加甚至减少则与源自联合区域的成分有关。来自非人灵长类动物的可比数据有限，而这些数据可以对这些强度 - 波幅差异背后的神经基质进行侵入性研究。为了更全面地描述这些关系，我们从5只松鼠猴（松鼠猴属）慢性植入的硬膜外电极记录了听觉ERP，以响应不同强度（50、60、70、80 dB SPL）的纯音（500 Hz，持续300毫秒）。在刺激后200毫秒内，在Fz记录的松鼠猴ERP显示出3个峰值。这些峰值包括一个正向波（P1），随后是一个负向波（N1），然后是另一个正向波（P2）。在后部部位，额部的P1 - N1构型被记录为N1 - P1复合波。在这些部位，一个小的负向波（N2）先于最后一个正向峰值（P2）出现。极性变化与参考部位无关，后部的N1 - P1峰值的潜伏期与额部的P1 - N1成分相似。在Fz、Cz和Pz处的波幅随着刺激强度的增加而大幅增加（“增强”）。相比之下，在T3和T4处，波幅仅出现小的增加甚至减少（“减弱”）。另一方面，在大多数部位，峰值潜伏期随着刺激强度的增加而缩短。特定部位的波幅反应表现出相当的时间稳定性。例如，在一名受试者中，在6个月的时间里，在8次记录中，Fz处记录到了类似的“增强”波形。猴子强度 - 波幅反应图谱的地形、它们的时间稳定性以及峰值潜伏期的变化与在人类中观察到的相似。数据表明，“增强”是猴子头顶电位的特征，与类似的人类电位一样，可能起源于初级听觉皮层。相比之下，在颞叶皮层记录到的电位可能起源于听觉联合皮层，表现出“减弱”。因此，数据支持这样的假设，即随着强度增加波幅的差异可能反映了皮层起源的差异。
