PT  - JOURNAL ARTICLE
AU  - Tsunehiko Kohashi
AU  - Natsuyo Nakata
AU  - Yoichi Oda
TI  - Effective Sensory Modality Activating an Escape Triggering Neuron Switches during Early Development in Zebrafish
AID  - 10.1523/JNEUROSCI.6169-11.2012
DP  - 2012 Apr 25
TA  - The Journal of Neuroscience
PG  - 5810--5820
VI  - 32
IP  - 17
4099  - http://www.jneurosci.org/content/32/17/5810.short
4100  - http://www.jneurosci.org/content/32/17/5810.full
SO  - J. Neurosci.2012 Apr 25; 32
AB  - Developing nervous systems grow to integrate sensory signals from different modalities and to respond through various behaviors. Here, we examined the development of escape behavior in zebrafish [45–170 h postfertilization (hpf)] to study how developing sensory inputs are integrated into sensorimotor circuits. Mature fish exhibit fast escape upon both auditory/vestibular (AV) and head-tactile stimuli. Newly hatched larvae, however, do not respond to AV stimuli before 75 hpf. Because AV-induced fast escape in mature fish is triggered by a pair of hindbrain neurons known as Mauthner (M) cells, we studied functional development of the M-cell circuit accounting for late acquisition of AV-induced escape. In fast escape elicited by head-directed water jet, minimum onset latency decreased throughout development (5 ms at 45–59 hpf, 3 ms after 75 hpf). After 75 hpf, lesioning the otic vesicle (OV) to eliminate AV input resulted in loss of short-latency (<5 ms) fast escape, whereas ablation of the sensory trigeminal ganglion (gV) to block head-tactile input did not. Before 75 hpf, however, fast escape persisted after OV lesion but disappeared after gV ablation. Laser ablation of the M-cell and Ca2+ imaging of the M-cell during escape demonstrated that M-cell firing is required to initiate short-latency fast escapes at every developmental stage and further suggest that head-tactile input activates the M-cell before 75 hpf, but that after this point AV input activates the M-cell instead. Thus, a switch in the effective sensory input to the M-cells mediates the acquisition of a novel modality for initiating fast escape.