Simultaneous recordings of pro-BDNF–induced synaptic depression and imaging of terminal retraction. (top) Time-lapse images showing progressive retraction of a nerve terminal from a myocyte after pro-BDNF treatment. The dotted circle indicates the myocytes recorded; the dotted line indicates the recording pipette; the arrows indicate the axon terminal. (bottom) Simultaneous recording of SSC recording. The recording shows a rapid and persistent decrease in SSC frequency after pro-BDNF application. Note that synaptic depression precedes axonal retraction from its target myocyte. n = 4 independent experiments. Bar, 10 µm.