NEURAL INTERACTION IN CAT PRIMARY AUDITORY-CORTEX - DEPENDENCE ON RECORDING DEPTH, ELECTRODE SEPARATION, AND AGE
NEURAL INTERACTION IN CAT PRIMARY AUDITORY-CORTEX - DEPENDENCE ON RECORDING DEPTH, ELECTRODE SEPARATION, AND AGE
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DOI：
10.1152/jn.1992.68.4.1216
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发表时间：
1992-10-01
影响因子：
2.5
通讯作者：
EGGERMONT, JJ
中科院分区：
文献类型：
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作者：
EGGERMONT, JJ
1.用两个独立的电极记录神经活动，两个独立的电极间隔0.5-2 mm，平行排列，垂直于猫听皮层表面前进。对于较小的分离，使用了极间距离为125微米的固态多电极阵列。两个独立可移动电极的记录深度之差从未超过100微米；多电极阵列的电极触点深度相同。因此，相关研究主要探讨了水平交互作用。在记录的995个神经元对中，478个代表单个单位对，而其他对被错误分类的棘波污染了5%-10%。只对单单元对进行了进一步分析。其中338个有明显的相关峰，其中329个峰高超过Z>；4显著水平(P<；0.0001)。252个显著相关图(占总数的53%)可归因于共同输入；其余的(占总数的16%)表示单侧兴奋。在181个单电极对中，单侧激发对的比例(42%)与共同输入对的比例(38%)大致相同。对于297对双电极，在184个显着相关性中，除一个外，所有的相关性都表明有共同的输入。未发现抑制相关图。峰清晰的相关图可分为窄型(n=40)、混合型(n=77)和宽型(n=221)。只有单电极对和混合电极对有两种例外；单电极对和双电极对有广泛的类型。单侧兴奋型以窄型相关图居多。计算了1ms双宽度(50ms超前/滞后时间)和10ms双宽度(500ms超前/滞后时间)的相关图。相关图由四个参数表征：中心峰半宽、峰相关系数、关联指数，对于单侧激发情况，也用有效性来表征。在所有三种相关图类型中，单电极对的相关峰的半宽(平均为27ms)明显小于双电极对的相关峰的半宽度(平均为42ms)。仅就宽型相关图而言，单电极对和双电极对的平均半宽没有显著差异。单电极对的相关系数(1ms bin相关图)(平均值为0.038)显著大于双电极对的相关系数(平均值为0.011)。同样的发现也适用于10毫秒的双宽度相关图。单电极对和双电极对的缔合指数没有显著差异。结合相关系数的显著差异，这表明单电极对的触发具有更好的同步性，但相关尖峰的数量保持不变。在77对单侧兴奋中，一个突触前峰平均产生0.4个突触后峰，其中61个为0.5，只有16个高于这个值。在突触后神经元爆裂的情况下，>；0.5的值是一致的。交叉相关图的参数作为记录在硬脑膜表面以下的深度的函数，作为电极间隔的函数，作为特征频率(CF)差的特征频率(CF)的特征频率(CF)的对的低倍频程的函数，以及作为年龄的函数。单电极对的相关系数随记录深度的增加而减小，无论是在单边激励情况下，还是在公共输入情况下。相反，对于双电极对，只有缔合指数随着深度的增加而减少。相关系数Rho的值没有变化，与OCATE的CF差值显著相关的百分比也没有变化(范围从0到1.75)。共同输入的单电极对(仅宽型，CF值差始终为0)的平均RHO等于0.021+/-0.019(平均值+/-SD)，显著高于CF值为零的双电极对(0.01%+/-0.012)。在出生后第二周中期，持续到出生后50天，单侧兴奋病例的相关系数相当高。平均值为0.27(个体值最高可达0.4)，此后随年龄增长逐渐下降。事实上，在90日龄及以上的小猫中没有观察到相关系数>；0.3。对于双电极管道，相关系数和关联指数都随着年龄的增加而增加。这可以解释为由于突触接触的数量增加，两个单位中不相关的自发活动量增加。这些观察还表明，一旦皮质突触形成，它必然会在很短的时间内成熟，相关系数的降低只是由于新形成的突触连接增加的“噪音”的结果。
1. Neural activity was arecorde with two independent electrodes separted by 0.5-2 mm, aligned in parallel, and advanced perpendicular to the surface of the cat auditory cortex. For smaller separations a solid-state multielectrode array with interelectrode distances of 125 mum was used. The difference in recording depths for the two independently movable electrodes was never more than 100 mum; the electrode contacts of the multielctrode array were at the same depth. Thus the correlation studies dominantly explored horizontal interactions.2. Out of 995 neuron pairs recorded, 478 represented pairs of single units, whereas the other pairs were contaminated with 5-10% misclassified spikes. Only the single-unit pairs were further analyzed. Of those piars, 338 showed a clear correlation peak, and in 329 of these the peak heights were exceeding the Z > 4 significance lwcwl (P < 0.0001). Two hundred fifty-two of the significant correlograms (53% of total) could be attributed to common input; the remaining (16% of total) were indicative of unilateral excitation. For the 181 single-electrode pairs the precentage of unilateral excitation pairs (42%) was about the same as teh percentage of common input paire (38%). For the 297 dual-electrode pairs all but one of the 184 significant correlations were indicative of common input. No correlograms indicative of inhibition were found.3. The correlograms with clear peaks were classified into three types: narrow (n = 40), mixed (n = 77), and broad (n = 221). Narros and mixed types were with two exceptions found only for single-electrode pairs; broad types were found for singel-and dual-electrode pairs. Narrow-type correlograms were in majority of the unilateral excitation type. Correlograms were calculated both for 1-ms binwidths (50-ms lead/lag time) and for 10-ms binwidth (500-ms lead/lag time). The correlograms were characterized by four parameters; the half width of the central peak, the peak correlation coefficient, the association index, and for unilateral excitation cases also by the effectiveness.4. Across all three correlogram types the half width of the correlation peaks was significantly smaller for single-electrode pairs (mean, 27 ms) than for dual-electrode pairs (mean, 42 ms). For broad-type correlograms only, the mean half widths were not significantly different between single- and dual-electrode pairs.5. The correlation coefficients (1-ms bin correlograms) were significantly larger for single-electrode pairs (mean, 0.038) than for dual-electrode pairs (mean, 0.011). The same was found for the 10-ms binwidth correlograms.6. The association index was not significantly different for single-and dual-electrode pairs. In combination with the significant difference in correlation coefficients, this suggests that firings of single-electrode pairs are better synchronized but that the number of associated spiked remains the same.7. For the 77 unilateral excitation pairs a presynatic spike produced on average 0.4 postsynaptic spikes, with 61 values < 0.5 and only 16 above that value. The values > 0.5 were consistently found in cases where the postsynaptic neuron was bursting.8. The parameters of the cross correlogram were studied as a function of recording depth below the dura surface, as a function of electrode separation in characteristic frequency (CF) difference in octaves above the lower CF of the pair, and as a function of age.9. The correlation coefficient for single-electrode pairs, in both the unilateral excitation and common input cases, decreased with recording depth. In contrast, for dual-electrode pairs, only the association index decreased with depth.10. There was no change in teh value of the correlation coefficient, rho, nor in the percentage of significant correlations with CF difference in ocatve (range, from 0 to 1.75). The mean rho for common input single-electrode pairs (broad type only, CF difference always 0) was equal to 0.021 +/- 0.019 (mean +/- SD) and was significantly higher than for dual-electrode pairs with zero CF difference (0.01 +/- 0.012).11. During the middle of the second postnatal week, and continuing up to 50 postnatal dys, the correlation coefficients for unilateral excitation cases were quite high. The mean value was 0.27 (with individual values up to 0.4) and thereafter decreased steadily with age. In fact, correlation coefficient values >0.3 were not observed in kittens of age 90 days and up. For dual-electrode piars both the correlation coefficient and the association index increased with age. This could be explained by an increase in the amount of uncorrelated spontaneous activity in both units as a result of an increas in the number of synaptic contacts. These observations also suggest that once a cortical synapse is formed it is essentailly mature a very short time thereafter, the decrease in correlation coefficients being only the result from the added "noise" from the newly formed synaptic connections.