highly significantP < 0.0001
The decline close to the cell bodies was not significant (37 ± 3% to 26 ± 4%; Figures 3E and 4A ; t -test, P < 0.08; n = 31), but the three-fold decline at longer distances (>250 μm) was highly significant (14 ± 2% at P36 to P40 to 4 ± 1% at >P41; t -test, P < 0.0001).