Forward Processing of Long-Term Associative Memory in Monkey Inferotemporal Cortex
Forward Processing of Long-Term Associative Memory in Monkey Inferotemporal Cortex
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DOI：
10.1523/jneurosci.23-07-02861.2003
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发表时间：
2003-04
期刊：
影响因子：
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通讯作者：
Y. Naya;Masatoshi Yoshida;Y. Miyashita
中科院分区：
文献类型：
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作者：
Y. Naya;Masatoshi Yoshida;Y. Miyashita
猕猴的颞下皮质作为视觉长期记忆的储存库，由两个不同但相互关联的区域组成：TE区(TE)和36区(A36)。在本研究中，我们检验了记忆编码是否在这个阶段被提出，即不同但语义相连的客体的表征之间的关联是否从TE前进到A36。为了解决这个问题，我们在配对联想(PA)记忆任务中训练猴子，之后在PA试验期间从TE和A36记录单个单位的活动。这两个区域的神经元都表现出刺激选择性线索反应(TE中347个，A36中76个；“线索选择神经元”)，这在群体水平上提供了配对伙伴之间的助记联系。在单个神经元水平上对配对伙伴的反应显著相关的神经元(“配对编码神经元”)的百分比显著增加，从TE(占线索选择神经元的4.9%)增加到A36(33%)。根据提示刺激呈现后的初始瞬时反应，A36中的配对编码神经元可进一步分为1型(68%)和2型(32%)。第一类神经元，而不是第二类神经元，一旦表现出刺激选择性，就开始编码成对刺激之间的联系。因此，A36中由1型神经元编码的长期记忆的表征很可能在没有其他高级中枢反馈输入的情况下得到证实。因此，我们得出结论，在IT皮层内，配对的联结的表征之间的关联在这一关键步骤中向前推进，这表明从编码单独视觉对象的两个TE神经元选择性地会聚到单个A36神经元。
The macaque inferotemporal (IT) cortex, which serves as the storehouse of visual long-term memory, consists of two distinct but mutually interconnected areas: area TE (TE) and area 36 (A36). In the present study, we tested whether memory encoding is put forward at this stage, i.e., whether association between the representations of different but semantically linked objects proceeds forward from TE to A36. To address this question, we trained monkeys in a pair-association (PA) memory task, after which single-unit activities were recorded from TE and A36 during PA trials. Neurons in both areas showed stimulus-selective cue responses (347 in TE, 76 in A36; “cue-selective neurons”) that provided, at the population level, mnemonic linkage between the paired associates. The percentage of neurons in which responses to the paired associates were significantly (p < 0.01) correlated at the single-neuron level (“pair-coding neuron”) dramatically increased from TE (4.9% of the cue-selective neurons) to A36 (33%). The pair-coding neurons in A36 were further separable into Type1 (68%) and Type2 (32%) on the basis of their initial transient responses after cue stimulus presentation. Type1 neurons, but not Type2 neurons, began to encode association between paired stimuli as soon as they exhibited stimulus selectivity. Thus, the representation of long-term memory encoded by Type1 neurons in A36 is likely substantiated without feedback input from other higher centers. Therefore, we conclude that association between the representations of the paired associates proceeds forward at this critical step within IT cortex, suggesting selective convergence onto a single A36 neuron from two TE neurons that encode separate visual objects.