Coordination between different motor centers is essential for the orderly production of all complex behaviors. Understanding the mechanisms of such coordination during feeding behavior in the carnivorous mollusk Clione limacina is the main goal of the current study. A bilaterally symmetrical interneuron identified in the cerebral ganglia and designated Cr-BM neuron produced coordinated activati...

Afferent regulation of centrally generated activity is likely to be more complex than has been established. We show that a neuron that is an exteroceptor can also function as a proprioceptor. We study the Aplysia neuron B21. Previous data suggest that B21 functions as an exteroceptor during the radula closing/retraction phase of ingestive feeding. We show that the tissue innervated by B21, the ...

The multitasking central pattern generator (CPG) that drives consummatory feeding behaviors of Aplysia can produce ingestive, egestive, and intermediate motor programs. External stimuli trigger the programs but, remarkably, do not directly specify which type of program is produced. Rather, recent work has proposed, the type of program is determined by the internal network state of the CPG that ...

Japanese species, Aplysia kurodai, feeds well on Ulva but rejects Gelidium (Geli.) or Pachydictyon (Pach.) with different rhythmic patterned movements of the jaws and radula. During ingestion the jaws open at the radula-protraction phase and remain half open at the initial phase of the radula-retraction, whereas during rejection the jaws open similarly but start to close immediately after the o...

BACKGROUND Learning in exploratory and goal-directed behaviors can modify decision-making processes in the initiation of appropriate action and thereby transform the irregular and infrequent expression of such behaviors into inflexible, compulsive-like repetitive actions. However, the neuronal mechanisms underlying such learning-derived behavioral plasticity remain poorly understood. RESULTS ...

Multifunctional central pattern generators (CPGs) are circuits of neurons that can generate manifold actions from a single effector system. This study examined a bilateral pair of pharyngeal motor neurons, designated B67, that participate in the multifunctional feeding network of Aplysia californica. Fictive buccal motor programs (BMPs) were elicited with four distinct stimulus paradigms to ass...

Plasticity of Aplysia feeding has largely been measured by noting changes in radula protraction. On the basis of previous work, it has been suggested that peripheral modulation may contribute to behavioral plasticity. However, peripheral plasticity has not been demonstrated in the neuromuscular systems that participate in radula protraction. Therefore in this study we investigated whether contr...

The paired supralateral radular retractor muscles of Planorbarius are innervated by eight (four pairs) of buccal motoneurones. Each motoneurone supplies both muscles, the ipsiand contralateral motor responses being similar, and identical to those produced by its contralateral partner. This arrangement apparently secures equivalence of motor output to the two muscles, irrespective of discrepanci...

Described is a new species of the genus Stenosemus from Gulf Alaska. It differs other this Northeast Pacific by having longitudinal undulating folds in pleural areas intermediate valves, flattened, smooth dorsal calcareous corpuscules on perinotum and rectangular central teeth radula.

Four new species of Anatomidae are described: Anatoma herberti n. sp. with strong axial sculpture on the shoulder and base; A. austrolissa n. sp. with almost smooth sculpture except for axial cords in the adumbilical half of the base; A. boucheti n. sp. with sunken protoconch and selenizone that starts after more than one teleoconch I whorl; and A. fl exidentata n. sp. with a highly modifi ed r...