Serotonergic and peptidergic modulation of buccal muscle contraction at an identified neuromuscular synapse in the African giant snail Achatina fulica was examined. A pair of excitatory motoneurons of the radula protractor was identified in the buccal ganglia and these were named B10 neurons. Pharmacological experiments revealed the B10s to be cholinergic. The serotonergic cerebral neuron v-CDN...

The periodicity of striae formation in the tropical scallop Comptopallium radula (Indo-West Pacific Ocean) was investigated with an in situ marking technique, using the calcein fluorochrome. To minimize scallop stress caused by excessive handling, in situ benthic chambers were used for marking experiments. Once marked, scallops (shell height range: 38.4-75.8 mm) remained on site in a large bent...

Complex behaviors often require coordinated movements of dissimilar motor structures. The underlying neural mechanisms are poorly understood. We investigated cycle-by-cycle coordination of two dissimilar feeding structures in Aplysia californica: the external lips and the internal radula. During feeding, the lips open while the radula protracts. Lip and radula motoneurons are located in the cer...

The buccal ganglion of Aplysia contains a heterogeneous population of peptidergic, radula mechanoafferent (RM) neurons. To investigate their function, two of the larger RM cells (B21, B22) were identified by morphological and electrophysiological criteria. Both are low-threshold, rapidly adapting, mechanoafferent neurons that responded to touch of the radula, the structure that grasps food duri...

We investigate stimulus specificity of repetition priming in a tractable model system; the feeding network of Aplysia. Previous studies primarily focused on an aspect of behavior that is altered during ingestive priming, radula opening. Priming of radula opening occurs when two modulatory peptides [feeding circuit activating peptide (FCAP) and cerebral peptide-2 (CP-2)] are released from the ch...

Changes in the positions, shapes and movements of the feeding apparatus (buccal mass) of the marine mollusc Aplysia californica were studied in intact, transilluminated juveniles. The buccal mass assumes characteristic shapes as its internal structure, the radula/odontophore, moves anteriorly (protracts) or posteriorly (retracts). These shapes are especially distinctive when the radula/odontoph...

Modern taxonomic studies of Agaricomycetes rely on the integrative analyses morphology, environmental data, geographic distribution, and usually several DNA loci. However, sampling selection loci for are commonly shallow. In this study, we suggest minimal numbers necessary specimens to sample analyze in order prevent inadequate decisions species groups with minor morphological genealogical diff...

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Five pairs of neurones, R(L)-B1, R(L)-B2, R(L)-B3, R(L)-B4 and R(L)-B5, controlling buccal muscle movement, were identified in the buccal ganglia of the African giant snail Achatina fulica Ferussac. All these neurones fired during the radula retraction phase of rhythmic buccal activity. Neurones Bl, B2, B4 and B5 made direct excitatory connections to the radula retractor, and Bl, B2, B3 and B5 ...

Motivated behaviors comprise appetitive actions whose occurrence results partly from an internally driven incentive to act. Such impulsive behavior can also be regulated by external rewarding stimuli that, through learning processes, can lead to accelerated and seemingly automatic, compulsive-like recurrences of the rewarded act. Here, we explored such behavioral plasticity in Aplysia by analyz...