The CPT neurons (cerebropleural ganglion triplets) are found in Hermissenda crassicornis.
NeuronBank Accession ID: Her0002693
All anatomical data from Tian et al., 2006. The CPT neurons are a cluster of three serotonin immunopositive neurons located in the posterior-medial portion of the cerebral ganglion that contribute to reflexive foot contractions in Hermissenda. The neurons receive sensory input from mechanoreceptors and photoreceptors and output onto VP2 motor neurons that control foot movements (Tian et al., 2006). The CPTs are homologues of the Tritonia diomedea DSIs (Newcomb and Katz, 2007), Pleurobranchaea californica As1-3 (Jing and Gillette, 1999), the Aplysia californica CC9-10 (Jing et al., 2008), the Clione limacina Cr-SP neurons (Panchin et al., 1995; Satterlie and Norekian, 1995) and the CeSP neurons that have been identified in Tochuina tetraquetra, Melibe leonina, Dendronotus iris, Dendronotus frondosus, Armina californica, Triopha catalinae (Newcomb and Katz, 2007).
Neuronal Type: Interneuron
Details from Tian et al., 2006
- The CPTs are located in a cluster in the posterior-medial portion of the cerebral ganglion (Figure 1).
- The CPTs project an axon contralaterally to the pedal ganglion and then through the pedal ganglia commissure (Figure 1).
- There are 6 CPTs in the brain (3 in each cerebral ganglion).
- Neurotransmitter: Serotonin (Tian et al., 2006)
All physiology details are from Tian et al., 2006.
CPT receives mechanosensory input from the anterior and middle foot region (Figure 2). The CPTs also receive input from type B photoreceptors (Figure 3). The CPTs receive polysynaptic inhibitory input from the Ib interneurons (see the Ib wiki page) and are electrically coupled to other CPT neurons.
The CPTs excite VP2 motor neurons, which control anterior foot contraction (Figure 4).
The CPTs are spontaneously active at rest and receive common synaptic input.
The CPT neurons synapse onto VP2 motor neurons which initiate anterior foot contractions. CPT neurons receive input from the eyes and foot. Thus, it appears as though the CPT neurons cause foot contractions when excited by light or foot stimulation. The CPTs do not appear to be involved in ciliary locomotion, however. Therefore, any involvement of the CPTs in locomotion appears to be relegated to turning via foot contraction.
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