A PAIR OF IDENTIFIED INTERNEURONS IN APLYSIA THAT ARE INVOLVED IN MULTIPLE BEHAVIORS ARE NECESSARY AND SUFFICIENT FOR THE ARTERIAL-SHORTENING COMPONENT OF A LOCAL WITHDRAWAL REFLEX
Yp. Xin et al., A PAIR OF IDENTIFIED INTERNEURONS IN APLYSIA THAT ARE INVOLVED IN MULTIPLE BEHAVIORS ARE NECESSARY AND SUFFICIENT FOR THE ARTERIAL-SHORTENING COMPONENT OF A LOCAL WITHDRAWAL REFLEX, The Journal of neuroscience, 16(14), 1996, pp. 4518-4528
A bilateral pair of cerebral interneurons, called CC5, contribute to t
he generation of a number of different behaviors involving head moveme
nts. Each cell sends its axon to the ipsilateral and contralateral ped
al and pleural ganglia. A weak tactile stimulus to the head excites th
e ipsilateral CC5; a strong stimulus excites both the ipsilateral and
contralateral cells. Firing of CC5 produces powerful shortening of the
ipsilateral pedal artery (PA) by means of monosynaptic excitation of
the pedal artery shortener (PAS) neuron, the single motor neuron for t
he artery. A weak touch to a tentacle excites the ipsilateral PAS and
evokes a local withdrawal response accompanied by shortening of the ip
silateral PA. In vivo recording of the pedal artery nerve (PAn) showed
that PAS was activated bilaterally during defensive head withdrawal e
licited by a strong stimulus and was activated unilaterally by a weak
stimulus. The responses were eliminated by cutting the ipsilateral cer
ebral-pleural connective (C-PLC). Electrical stimulation of the cerebr
al-pleural connective provided evidence that all of the excitatory inp
ut to PAS via this connective is provided by CC5. A variety of experim
ental results indicates that during a local withdrawal reflex of the t
entacle, CC5 is necessary and sufficient for the unilateral PA-shorten
ing component of the response and therefore functions as a command neu
ron for a component of the behavior. The data suggest that during defe
nsive head withdrawal, the two CC5 neurons may act conjointly as a two
-neuron command system that is necessary and sufficient for the bilate
ral arterial-shortening component of the behavior.