Javitt D C, Steinschneider M, Schroeder C E, Vaughan H G, Arezzo J C
Department of Psychiatry, Albert Einstein College of Medicine, Bronx, NY 10461.
Brain Res. 1994 Dec 26;667(2):192-200. doi: 10.1016/0006-8993(94)91496-6.
Mismatch negativity (MMN) is a cognitive, auditory event-related potential (AEP) that reflects preattentive detection of stimulus deviance and indexes the operation of the auditory sensory ('echoic') memory system. MMN is elicited most commonly in an auditory oddball paradigm in which a sequence of repetitive standard stimuli is interrupted infrequently and unexpectedly by a physically deviant 'oddball' stimulus. Electro- and magnetoencephalographic dipole mapping studies have localized the generators of MMN to supratemporal auditory cortex in the vicinity of Heschl's gyrus, but have not determined the degree to which MMN reflects activation within primary auditory cortex (AI) itself. The present study, using moveable multichannel electrodes inserted acutely into superior temporal plane, demonstrates a significant contribution of AI to scalp-recorded MMN in the monkey, as reflected by greater response of AI to loud or soft clicks presented as deviants than to the same stimuli presented as repetitive standards. The MMN-like activity was localized primarily to supragranular laminae within AI. Thus, standard and deviant stimuli elicited similar degrees of initial, thalamocortical excitation. In contrast, responses within supragranular cortex were significantly larger to deviant stimuli than to standards. No MMN-like activity was detected in a limited number to passes that penetrated anterior and medial to AI. AI plays a well established role in the decoding of the acoustic properties of individual stimuli. The present study demonstrates that primary auditory cortex also plays an important role in processing the relationships between stimuli, and thus participates in cognitive, as well as purely sensory, processing of auditory information.
失匹配负波（MMN）是一种认知性听觉事件相关电位（AEP），它反映了对刺激偏差的前注意检测，并为听觉感觉（“回声”）记忆系统的运作提供指标。MMN最常见于听觉oddball范式中，在该范式中，一系列重复的标准刺激会被一个物理上不同的“oddball”刺激偶尔且意外地打断。脑电图和脑磁图偶极子映射研究已将MMN的产生源定位到Heschl回附近的颞上听觉皮层，但尚未确定MMN在多大程度上反映初级听觉皮层（AI）自身的激活情况。本研究通过将可移动的多通道电极急性插入颞上平面，证明了AI对猴子头皮记录的MMN有显著贡献，这表现为AI对作为偏差刺激呈现的大声或小声点击的反应比对作为重复标准呈现的相同刺激的反应更大。类似MMN的活动主要定位于AI内的颗粒上层。因此，标准刺激和偏差刺激引发了相似程度的初始丘脑皮质兴奋。相比之下，颗粒上层皮质对偏差刺激的反应比对标准刺激的反应明显更大。在少数穿过AI前方和内侧的通道中未检测到类似MMN的活动。AI在解码单个刺激的声学特性方面发挥着既定作用。本研究表明，初级听觉皮层在处理刺激之间的关系方面也起着重要作用，因此参与了听觉信息的认知处理以及纯粹的感觉处理。
