Fig. 3.

BDNF modulates the frequency activity of isolated bursting neurons. (A) Top: Fluorescent images of an E16.5 transverse medullary slice taken at low (left) and high (middle) magnification following loading with the calcium indicator Calcium Green 1-AM. Note the recording electrode positioned at the surface of the slice in the preBötC region. The white rectangle delimits the area that contains rhythmic neurons and is shown at higher magnification in the middle panel with each of the cells numbered 1–10. An example of calcium transients visualized in these cells is shown in the right panel as relative changes in fluorescence (ΔF/F). The traces in A–C display the calcium transients recorded from neurons 1–10 in control conditions (A), blocker cocktail (20 μM CNQX, 50 μM AP5, 10 μM bicuculline, 5 μM strychnine and 50 μM carbenoxolone) (B) and blocker cocktail plus 100 ng/mL BDNF for 15 min (C). Calcium changes occurring in the preBötC area are shown in the green trace (preBötC) and electrical activity recorded in the contralateral preBötC is represented as the integrated trace (Int preBötC). In cocktail, population activity ceases (flat green trace and flat integrated recording) and synchronized calcium events disappear. The red traces highlight two neurons exhibiting endogenous bursting properties, neurons that remain rhythmically active after intra-network connectivity blockade. In the presence of BDNF the bursting frequency of these neurons increases (compare the red traces in B and C).