Cerebral Cortex 19(9): 2065–2077; 2009

In the above article, the standard deviations (SDs) of the quantitative data were incorrect except for those in Figure 4C. We mistakenly wrote the mean absolute deviation instead of the SD in the text and Table 2. However, the probability for judging statistical significance was appropriately calculated in all the quantitative data. The corrected forms are presented below:

Table 2.

Axonal arborization of motor thalamic neurons in the cerebral cortical areas

Neuron Total axon length in cortex varicosities (µm)a Estimated number of varicosities in cortexb Axon length in layer I (µm)a Estimated number of in layer Ib 
IZ 
175246 19681 80838 (46.1%) 9215 (46.8%) 
186336 20545 96765 (51.9%) 10644 (51.8%) 
181606 20240 97666 (53.8%) 10939 (54.0%) 
290706 33143 146159 (50.3%) 16954 (51.2%) 
197204 22486 129431 (65.6%) 14885 (66.2%) 
Mean 206220 23219 110172 (53.5%) 12527 (54.0%) 
±SD ±47906 ±5647 ±26752 (±7.3%) ±3248 (±7.3%) 
EZ 
131261 14594 7566 (5.8%) 870 (6.0%) 
217210 23992 6153 (2.8%) 689 (2.9%) 
214979 24903 5254 (2.4%) 599 (2.4%) 
385131 42069 55022 (14.3%) 6162 (14.6%) 
10 221815 25357 6374 (2.9%) 733 (2.9%) 
Mean 234079 26183 16074 (5.6%) 1811 (5.8%) 
± SD ±92450 ±9922 ±21788 (±5.0%) ±2434 (±5.1%) 
Neuron Total axon length in cortex varicosities (µm)a Estimated number of varicosities in cortexb Axon length in layer I (µm)a Estimated number of in layer Ib 
IZ 
175246 19681 80838 (46.1%) 9215 (46.8%) 
186336 20545 96765 (51.9%) 10644 (51.8%) 
181606 20240 97666 (53.8%) 10939 (54.0%) 
290706 33143 146159 (50.3%) 16954 (51.2%) 
197204 22486 129431 (65.6%) 14885 (66.2%) 
Mean 206220 23219 110172 (53.5%) 12527 (54.0%) 
±SD ±47906 ±5647 ±26752 (±7.3%) ±3248 (±7.3%) 
EZ 
131261 14594 7566 (5.8%) 870 (6.0%) 
217210 23992 6153 (2.8%) 689 (2.9%) 
214979 24903 5254 (2.4%) 599 (2.4%) 
385131 42069 55022 (14.3%) 6162 (14.6%) 
10 221815 25357 6374 (2.9%) 733 (2.9%) 
Mean 234079 26183 16074 (5.6%) 1811 (5.8%) 
± SD ±92450 ±9922 ±21788 (±5.0%) ±2434 (±5.1%) 

a The length of axon fibers was estimated by multiplying the length of varicose axons projected onto parasagittal plane by π/2. Thus, the measured axons did not contain thick straight axon fibers, which might be myelinated portions of thalamocortical axons and make no synaptic contacts.

b The estimated number of varicosities in each cortical layer was calculated by multiplying, in each layer, axon length by the density of varicosities. The mean density of varicosities was, in each layer, measured with 20 randomly selected axon fibers, which were longer than 100 µm. See Supplementary Table for the original data.

On page 2069 (left column, last line–right column, line 4), “we observed no significant difference (p = 0.81 by the 2-tailed unpaired t-test) between the areas of IZ and EZ neuronal cell bodies, which were 245 ± 24 and 250 ± 33 µm2 (mean ± standard deviation [SD])”.

On page 2070 (left column, line 6 from bottom–right column, line 2), “The varicosity densities along palGFP- and GFP-labeled axon fibers in motor cortical areas were 112 ± 23/mm (mean ± SD; n = 918; data from Supplementary Table) and 115 ± 22/mm (n = 50), respectively. The size of varicosities and the thickness of intervaricosity axon fibers were 1.70 ± 0.42 and 0.91 ± 0.08 µm (n = 100 and 50) in palGFP-labeled axon fibers and 1.74 ± 0.46 and 0.89 ± 0.10 µm (n = 100 and 50) in GFP-labeled ones”.

On page 2073 (left column, last 3 lines), “This concept is in a good agreement with the present results that IZ neurons sent 54 ± 7% of their axons to layer I of relatively wide areas”.