CC7

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CC7 is a cerebral-abdominal interneuron in Aplysia californica.

Neuronal schematic of CC7. (Xin 2001)

Basic information

  • CC7 acts to coordinate signaling between the cerebral and abdominal ganglia, as these ganglia mediate various behaviors. In addition to its action in interganglionic coordination of neurons innervating non-somatic organs, CC7 is considered an important factor in the neural foundation of food-induced arousal; and it may function to coordinate feeding behavior.

Identification

Anatomy

  • Unilateral symmetry is observed in the right side of the soma.
  • The main axonal projection extends to the contralateral pleural ganglion. It divides in the pleural ganglion. Then one branch goes to the abdominal ganglion, using the pleural-abdominal connective. The other is sent to the ipsilateral pedal ganglion and further to the contralateral pleural-pedal ganglion.
Excitation of RB-he by CC7 A:One-for-one EPSPs from CC7. B:Persistent EPSPs in a high divalent cation solution. (Xin 2001)

Electrophysiology

  • Inhibitory synaptic input is evoked with stimulation of the lips or anterior tentacles. Upon retraction of the radula and movement of the buccal mass, there is a decrease in CC7 spiking. The backward and forward buccal mass movement exhibited in feeding behavior is accompanied by CC7 firing in phase with movement of the buccal mass. Synaptic input from locomotor activity is tonic.
  • CC7 also excites the LB-vc motor neurons that innervate the abdominal artery. Given the connection between CC7 and the LB-vc cells, a large contraction is generated in the abdominal artery due to EPSPs from CC7. In addition to eliciting a contractile response in the abdominal artery, its firing produces contractions of the heart muscle. Firing also stimulates RB-he, a serotonergic cardiac motor neuron. EPSPs produced in either situation are one-for-one with CC7 firing. Each connection also appears monosynaptic.
  • Another non-cardiovascular action is the slow, weak excitation of the left upper quadrant cells.
  • There is also a relationship of mutual inhibition between CC7 and C-PR. The cerebral-pedal regulator neuron (C-PR) is affiliated with lengthening of the neck and the head-up response. This inhibitory relationship provides further evidence for the role of CC7 in feeding behavior, specifically appetitive responses.

References

1. Skelton ME, and Koester J. The morphology, innervation and neural control of the anterior arterial system of Aplysia californica. J Comp Physiol [A] 171: 141-155, 1992. PMID: 1359129

2. Teyke T, Weiss KR, and Kupfermann I. An identified neuron (CPR) evokes neuronal responses reflecting food arousal in Aplysia. Science 247: 85–87, 1990. PMID: 2294596

3. Xin Y, Koester J, Jing J, Weiss KR, and Kupfermann I. (2001) Cerebral-abdominal interganglionic coordinating neurons in Aplysia. J Neurophysiol 85: 174–186. Full text (html)