J Cogn Neurosci. 1991 Summer;3(3):293-9. doi: 10.1162/jocn.1991.3.3.293.
Abstract Single-unit recording of layer II-III cells in olfactory (piriform) cortex was performed on awake, unrestrained rats actively engaged in learning novel odors in an olfactory discrimination task. Five of the 67 cells tested had very brief monophasic action potentials and high spontaneous firing rates (30-80 Hz); it is suggested that these units were interneurons. The remainder of the neurons had broader spikes and did not discharge for prolonged periods. Thirty-nine percent of the broad spike cells responded to at least one and usually more of the odors presented to the rats during either of the first two trials on which that odor was present, but, in most cases, these responses occurred only very infrequently over the course of subsequent trials. Six percent of the broad-spike group, how ever, continued firing robustly to a single odor but not to others. From these results it appears that most cells in piriform cortex do not respond to most odors, i.e., coding is exceedingly sparse. A subgroup of the predominant broad-spike cell type does react to several odors but this response drops out with repeated exposure, perhaps because of training. However, a few members of this class (a small fraction of the total cell population) do go on responding to a particular odor, thus exhibiting a form of odor specificity. The results are discussed with regard to predictions from recently developed models of the olfactory cortex.
在清醒、不受约束的大鼠进行嗅觉辨别任务（主动学习新气味）时，我们对嗅（梨状）皮层 II-III 层的单个细胞进行了记录。在 67 个测试的细胞中，有 5 个细胞的动作电位非常短暂且自发放电率很高（30-80 Hz）；这些细胞可能是中间神经元。其余的神经元的尖峰较宽，不会长时间放电。39%的宽尖峰细胞对至少一种、通常是在该气味存在的前两次试验中的一种气味有反应，但在大多数情况下，这些反应在随后的试验中只是非常罕见地发生。然而，宽尖峰细胞群中的 6%会继续强烈地对单个气味作出反应，但不会对其他气味作出反应。从这些结果来看，梨状皮层中的大多数细胞对大多数气味没有反应，即编码非常稀疏。占主导地位的宽尖峰细胞类型的一个亚组确实对几种气味有反应，但这种反应随着反复暴露而消失，可能是因为经过了训练。然而，这个类别中的少数成员（总细胞群体的一小部分）确实会继续对特定的气味作出反应，从而表现出某种形式的气味特异性。结果与最近开发的嗅觉皮层模型的预测进行了讨论。
