Figure 8.

Locating anterior lateral line (aLL) nerve sensory interneurons using calcium imaging. A: experimental setup for calcium imaging using a ×10 water immersion objective. The brain is open and the preparation is tilted so that the left side of the hindbrain stays roughly flat to facilitate the imaging of many neurons in a single focal plane. Images have been acquired at 10 Hz. fb, forebrain; hb, hindbrain; m, myotome; mb, midbrain; sc, spinal cord. B: three frames captured at the indicated time points in D (1, 2, and 3). Lines in frame 1 show the dorsal and ventral boundaries of the hindbrain (dotted rectangle region in A). Circles in frame 1 indicate regions of interest (ROIs) where calcium activities are given in C. C: calcium activity of 11 neurons outlined by color-coded circles in B. Different types of responses are grouped as labeled. D: simultaneous motor nerve (m.n.) and suction recordings with inset showing initial m.n. bursts. E: summary of locations of neurons showing increased calcium activity time-locked with suction stimulation. F: examples of neurons in the lateral line (LL) nucleus region, rostral hindbrain, and midbrain to show differences in their calcium activity latencies and peak time. Summary of fluorescence peak value (G), number of frames to reach 20% peak fluorescence (H), and number of frames to reach peak fluorescence (I, all independent-samples Kruskal–Wallis test in G–I) in ROIs in the three brain areas following suction that has evoked swimming. J: comparing fluorescence increase at the beginning of swimming evoked by suction and at the beginning of spontaneous swimming (related-samples Wilcoxon signed rank test). Numbers of neurons used in statistics are given in brackets below the charts and significance levels in G–J: *P < 0.05; **P < 0.01. The same color-coding applies to E–J.