THALAMOCORTICAL RESPONSE TRANSFORMATION IN THE RAT VIBRISSA BARREL SYSTEM
THALAMOCORTICAL RESPONSE TRANSFORMATION IN THE RAT VIBRISSA BARREL SYSTEM
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DOI：
10.1152/jn.1989.61.2.311
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发表时间：
1989-02-01
影响因子：
2.5
通讯作者：
CARVELL, GE
中科院分区：
文献类型：
--
作者：
SIMONS, DJ;CARVELL, GE
细胞外单单位记录和控制胡须刺激被用来比较反应特性的细胞之间的“barreloids”的丘脑ventrobasal复合体和那些在细胞色素氧化酶丰富的中心的“桶”在第一躯体感觉皮层。个别触须偏转单独或成对的组合，涉及神经元的最大兴奋胡须和相邻的一个在相同或相邻的胡须行。定量数据来自26只正常成年大鼠记录的135个丘脑皮质单位（TCU），242个“常规尖峰”桶单位（RSU）和16个“快速尖峰”桶单位（FSU）。与TCU相比，RSU显示较低的自发活动率，对触须刺激的反应也不那么强烈。按比例，超过两倍的TCU RSU响应缓慢适应的方式，至少一个角方向的晶须位移。缓慢适应的TCU的放电为约。3.5比那些适应缓慢的RSU大一倍。成比例地，大约两倍的TCU比RSU选择性地响应不同角度方向的触须运动。丘脑中的细胞比皮层中的RSFU对更大数量的胡须反应更强烈。根据不同的刺激条件，两到三倍的TCU比RSU被两个或更多的晶须激发。位移的相邻晶须，单位放电到随后的偏转的最大兴奋性晶须减少在一个时间依赖性的方式。TCU和RSU的反应抑制的时间过程是相似的，但相邻的胡须之间的抑制相互作用在丘脑中观察到少得多。刺激诱发的兴奋/抑制的周期性模式的特征反应在皮质桶，但在丘脑barreloids是相当不明显。反应抑制的存在和/或程度取决于哪根邻近的触须受到刺激以及触须运动的角度方向。对于单个TCU，一些相邻的胡须诱发抑制，其他没有。绝大多数RSU显示对所有相邻触须的反应抑制。与TCU的感受野不同，RSU的感受野具有小的sbd，即，单须。sbd。兴奋中心与有效的和对称的抑制包围。快速穗单位在桶显示最大的自发和刺激诱发的活动，并在不同的角度方向的晶须运动的选择性最小。FSUs有最大的兴奋性受体领域，100%响应两个或更多的触须。桶电路将丘脑信号转换为空间代码和时间代码，空间代码增强了来自相邻触须的输入之间的对比度，时间代码建立了皮层兴奋和抑制的特征模式。
Extracellular single-unit recordings and controlled whisker stimuli were used to compare response properties between cells in the "barreloids" of the thalamic ventrobasal complex and those in the cytochrome oxidase-rich centers of the "barrels" in the first somatic sensory cortex. Individual vibrissae were deflected alone or in paired combination involving the neuron''s maximally excitatory whisker and an adjacent one in the same or neighboring whisker rows. Quantitative data were derived from 135 thalamocortical unit''s (TCUs), 242 "regular-spike" barrel units (RSUs), and 16 "fast-spike" barrel units (FSUs) recorded in 26 normal adult rats. Compared with TCUs, RSUs displayed lower rates of spontaneus activity and responded less vigorously to whisker stimuli. Proportionally, more than twice as many TCUs as RSUs responded in slowly adapting fashion to at least one angular direction of whisker displacement. Discharges of slowly adapting TCUs were .apprx. 3.5 times greater than those of slowly adapting RSUs. Proportionally, about twice as many TCUs than RSUs responded selectively to whisker movements in different angular directions. Cells in the thalamus responded more vigorously to a larger number of whiskers than RSFUs in the cortex. Depending on the stimulus conditions, two to three times more TCUs than RSUs were excited by two or more whiskers. Following displacement of an adjacent whisker, unit discharges to subsequent deflections of the maximally excitatory whisker were reduced in a time-dependent fashion. The time course of response suppression was similar in TCUs and RSUs, but inhibitory interactions between adjacent whiskers were observed much less often in the thalamus. A cyclic pattern of stimulus-evoked excitation/inhibition characterizes responses in the cortical barrels but is considerably less pronounced in the thalamic barreloids. The presence and/or degree of response suppression depended on which adjacent whisker was stimulated and on the angular direction of that whisker''s movement. For individual TCUs, some adjacent whiskers evoked inhibition, others did not. The vast majority of RSUs displayed response suppression to all adjacent whiskers. Unlike receptive fields of TCUs, those of RSUs have small.sbd.i.e., single-whisker.sbd.excitatory centers with potent and symmetrical inhibitory surrounds. Fast-spike units in the barrels displayed the greatest spontaneous and stimulus-evoked activities and were the least selective for whisker movements at different angular directions. FSUs had the largest excitatory receptor fields; 100% responded to two or more vibrissae. Barrel circuitry transforms the thalamic signal into a spatial code that enhances contrast among inputs from adjacent whiskers and a temporal code that establishes a characteristic pattern of cortical excitation and inhibition.