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Patch-clamp recordings reveal a motor-related voltage signal in tectal neurons. a Schematic of the visuomotor pathway in larval zebrafish, including the retina, the optic tectum, hindbrain premotor circuits, spinal cord and axial tail muscles. Visual stimuli of different behavioral value (e.g. loom vs small, prey-like) are processed in the contralateral tectal hemisphere and trigger aversive (escape, red) or target-directed swims (approach, blue) through parallel pathways into the hindbrain premotor circuitry. Putative swim-related feedback signals may affect tectal visual processing during phases of swimming (corollary discharge, yellow). b Recording configuration. Whole-cell patch clamp recording from a tectal neuron is combined with bilateral extracellular field recordings from tail motor nerves (MNRipsi and MNRcontra). c Recorded tectal neuron (red) labeled with sulforhodamine-B via the patch pipette in Tg(pou4f1-hsp70l:GFP) transgenic background (cyan). PVL periventricular cell body layer. Micrograph representative of 56 independent experiments. d Example recording of membrane voltage (Vm, black) in a tectal neuron during a spontaneous fictive swim bout (MNRipsi, MNRcontra, blue and red, respectively). Inset: magnified view of swim event (onset indicated by dotted line). Note the associated short hyperpolarization in the voltage trace (arrow). e Swim-triggered average of voltage signals in tectal neurons (bottom solid trace: mean; shaded area: ± SEM; average across 21 individual, baseline-subtracted cell averages). Vm traces were aligned by the onset of swimming (vertical arrow), measured as the first burst in a fictive swim bout. Top: Standard deviation traces of motor nerve recordings (average from 330 swim events). Source data are provided as a Source Data file.
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