FB2026_03 , released September 17, 2026
CV Term Report
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Term larval A02b neuron ID (Ontology) FBbt:00111664 (Fly Anatomy)
Definition Larval period-positive median segmental interneuron (PMSI) (Kohsaka et al., 2019) that is late-born in the NB2-1 Notch OFF primary hemilineage (Mark et al., 2021). Like other PMSIs it has a ventral soma and it extends dorsally, close to the midline, then forms a loop in the dorsal neuropil (Kohsaka et al., 2019). This neuron has a relatively large amount of dendritic arborization around the midline, crossing into the contralateral hemineuromere (Schneider-Mizell et al., 2016; Kohsaka et al., 2019). It receives input from the proprioceptors dmd1 (dda1), ddaD and vbp, and outputs onto the ipsilateral A03a1 (eIN-4) (axo-axonic connection) and RP2 motor neuron (Schneider-Mizell et al., 2016).[ FlyBase:FBrf0231328 FlyBase:FBrf0242656 FlyBase:FBrf0249021 ]
Also Known As"looper-2"
CommentThese neurons were identified in a EM reconstruction of a volume that includes the posterior half of abdominal segment 2 and abdominal segment 3, of a 12-24h old first instar larva. The number of connections was estimated from the publication figures. The number of input synapses was the following (number in brackets left/right; ipsi- and contralateral connections separated by comma): from dda1 (15, 15/15, 15), ddaD (10, 4/15, 15), vbp (15, 8/15, 10), A02a (8, 18/20, 18). The number of output synapses was the following: to A03a1 (15/20), A02a (5/10), A1-7 dorsal motor neuron (12/12) (Schneider-Mizell et al., 2016).
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VFB:FBbt_00111664
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 larval A02b neuron (all annotations which use CV term, excluding "NOT" statements)
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larval ventral nerve cord
 |__period-positive median segmental interneuron__
lineage NB2-1 primary interneuron                 |
 |__period-positive median segmental interneuron__|
sensory system neuron                             |
 |__proprioceptive system neuron__________________|
Notch OFF hemilineage primary neuron              |
 |__NB2-1 Notch OFF hemilineage primary neuron____|
NB2-1 lineage primary neuron                      |
 |__NB2-1 Notch OFF hemilineage primary neuron____|
larval premotor neuron                            |
 |__period-positive median segmental interneuron__|
larval interneuron                                |
 |__period-positive median segmental interneuron__|
proprioceptive system                             |
 |__proprioceptive system neuron__________________|
larval glutamatergic neuron                       |
 |__period-positive median segmental interneuron__|
                                                  larval A02b neuron  2 rec.
                                                   |__larval abdominal 1 A02b neuron
                                                   |__larval abdominal 2 A02b neuron
                                                   |__larval abdominal 3 A02b neuron
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Is a NB2-1 Notch OFF hemilineage primary neuron
proprioceptive system neuron
period-positive median segmental interneuron
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VFB:FBbt_00111664