Mean branch rates and termination probabilities in layer 5 and layer 4 ed for cells from standard media (filled bars) and TTX groups (open bars). A, In standard media, the rate at which axon collaterals branch in layer 4 is significantly higher than layer 5, but there is not a difference in TTX. B, For both standard media and TTX groups, the termination probability is significantly higher in layer 4 ed than layer 5. Comparisons of values in layer 4 ed between the standard media and TTX groups show a reduction of the branch rates and termination probabilities in layer 4 ed. §p = 0.06. Significant difference between values in layer 4 ed and layer 5: *p < 0.05; **p < 0.01.