Fahy F L, Riches I P, Brown M W
Department of Anatomy, University of Bristol, School of Medical Sciences, UK.
Exp Brain Res. 1993;96(3):457-72. doi: 10.1007/BF00234113.
Recordings of the activity of 2705 single neurones were made in entorhinal and perirhinal cortex, area TG of the temporal lobe, and the inferior temporal cortex both during monkeys' performance of a serial recognition memory task using complex pictures and when monkeys were shown objects. Responses of 120 (9.7%) of the visually responsive neurons recorded were significantly smaller to the second than to the first presentations of unfamiliar stimuli. The incidence of such responses was highest in perirhinal cortex plus areas TE1 and TE2 of the temporal lobe, intermediate in lateral entorhinal cortex and areas TE3 and TG, and lowest in other parts of entorhinal and inferior temporal cortex. Response decrements were maintained across 20 or more intervening presentations of other stimuli for the majority of the neurones tested. Responses of 43 (14.4%) of the visually responsive neurones tested were significantly greater to unfamiliar than to highly familiar stimuli. Such differential responses were found only in lateral entorhinal and perirhinal cortex plus areas TG, TE1, TE2 and TE3. For 6 neurones the response difference was significant even when the familiar stimuli had not been seen for more than 24 h: such neurones demonstrate access to information stored in long-term memory for more than 24 h. Seven familiarity neurones signalled information concerning the relative familiarity of stimuli but not information concerning how recently they were last seen; 58 recency neurones signalled information concerning the recency of presentation of stimuli, but not their relative familiarity. Thus certain neurones demonstrate the separable encoding of recency and familiarity information. Neurones signalling information of use for recognition memory are found in cortex close to the rhinal sulcus where lesions result in major deficits in the performance of recognition memory tasks. The conjunction of these findings provides strong evidence for the importance of these neurones and this cortex for processes (recency and familiarity discrimination) necessary for recognition and working memory. The possible relation of the neuronal responses to priming memory is also discussed.
在猴子使用复杂图片执行序列识别记忆任务期间以及向猴子展示物体时，对2705个单神经元在内嗅皮层、嗅周皮层、颞叶TG区和颞下皮层的活动进行了记录。在记录的视觉反应神经元中，有120个（9.7%）对不熟悉刺激的第二次呈现的反应明显小于第一次呈现。这种反应的发生率在嗅周皮层加上颞叶的TE1和TE2区最高，在外侧内嗅皮层以及TE3和TG区居中，在内嗅皮层和颞下皮层的其他部分最低。对于大多数测试的神经元，在20次或更多次插入其他刺激的呈现过程中，反应递减得以维持。在测试的视觉反应神经元中，有43个（14.4%）对不熟悉刺激的反应明显大于对高度熟悉刺激的反应。这种差异反应仅在外侧内嗅皮层和嗅周皮层加上TG、TE1、TE2和TE3区发现。对于6个神经元，即使熟悉刺激已经超过24小时未被看到，反应差异仍然显著：这些神经元表明能够获取存储在长期记忆中超过24小时的信息。7个熟悉度神经元发出关于刺激相对熟悉度的信息，但不发出关于它们最后一次被看到的时间的信息；58个新近度神经元发出关于刺激呈现新近度的信息，但不发出它们的相对熟悉度的信息。因此，某些神经元表现出新近度和熟悉度信息的可分离编码。在靠近嗅沟的皮层中发现了发出用于识别记忆的信息的神经元，在这些部位的损伤会导致识别记忆任务表现的重大缺陷。这些发现的结合为这些神经元和这个皮层对于识别和工作记忆所必需的过程（新近度和熟悉度辨别）的重要性提供了有力证据。还讨论了神经元反应与启动记忆的可能关系。
