Temporal frequency of whisker movement. II. Laminar organization of cortical representations
Temporal frequency of whisker movement. II. Laminar organization of cortical representations
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DOI：
10.1152/jn.2001.86.1.354
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发表时间：
2001-07-01
影响因子：
2.5
通讯作者：
Haidarliu, S
中科院分区：
文献类型：
--
作者：
Ahissar, E;Sosnik, R;Haidarliu, S
通过啮齿动物的胡须获得的部分信息是由它们的运动频率携带的。在被麻醉的大鼠的丘脑中，须频率由两种不同的编码方案表示：丘脑侧的振幅和尖峰计数（即，响应振幅和尖峰计数随频率而减少）和丘脑旁的潜伏期和尖峰计数（潜伏期增加和尖峰计数随频率而减少）（见随附论文）。在这里，我们研究了麻醉大鼠初级体感皮层（“桶”）中须频率的神经元表征，该皮层从丘脑核和旁丘脑核接收其输入。在振动刺激过程中，从第2/3层、第4层（仅桶）、第5a层和第5b层记录了单个和多个单元。通常，输入频率由第4层和第5b层（“平行神经层”）中的幅值和尖峰数以及第5a层（“平行神经层”）中的潜伏期和尖峰数表示。第2/3层的神经元显示了两种编码方案的混合。当刺激脉宽从50 ms减小到20 ms时，潜伏期编码在5a和2/3层显著减少，而峰值计数编码不受影响；相比之下，在第4层和第5b层，潜伏期保持不变，但在20ms刺激下，尖峰计数减少。同样的效果也分别在丘脑旁核和丘脑左核中被发现（见随附论文）。这些结果与不同通路的丘脑皮层回路虽然终止于相同的皮质柱，但并行执行不同的计算的想法是一致的。此外，第2/3层编码方案的混合可能反映了前文和平行文输出的整合。
Part of the information obtained by rodent whiskers is carried by the frequency of their movement. In the thalamus of anesthetized rats, the whisker frequency is represented by two different coding schemes: by amplitude and spike count (i.e., response amplitudes and spike counts decrease as a function of frequency) in the lemniscal thalamus and by latency and spike count (latencies increase and spike counts decrease as a function of frequency) in the paralemniscal thalamus (see accompanying paper). Here we investigated neuronal representations of the whisker frequency in the primary somatosensory ("barrel") cortex of the anesthetized rat, which receives its input from both the lemniscal and paralemniscal thalamic nuclei. Single and multi-units were recorded from layers 2/3, 4 (barrels only), 5a, and 5b during vibrissal stimulation. Typically, the input frequency was represented by amplitude and spike count in the barrels of layer 4 and in layer 5b (the "lemniscal layers") and by latency and spike count in layer 5a (the "paralemniscal layer"). Neurons of layer 2/3 displayed a mixture of the two coding schemes. When the pulse width of the stimulus was reduced from 50 to 20 ms, the latency coding in layers 5a and 2/3 was dramatically reduced, while the spike-count coding was not affected; in contrast, in layers 4 and 5b, the latencies remained constant, but the spike counts were reduced with 20-ms stimuli. The same effects were found in the paralemniscal and lemniscal thalamic nuclei, respectively (see accompanying paper). These results are consistent with the idea that thalamocortical loops of different pathways, although terminating within the same cortical columns, perform different computations in parallel. Furthermore, the mixture of coding schemes in layer 2/3 might reflect an integration of lemniscal and paralemniscal outputs.