The Consistency of Gastropod Identified Neurons Distinguishes Intra-Individual Plasticity From Inter-Individual Variability in Neural Circuits.

Gastropod mollusks are known for their large, individually identifiable neurons, which are amenable to long-term intracellular recordings that can be repeated from animal to animal. The constancy of individual neurons can help distinguish state-dependent or temporal variation within an individual from actual variability between individual animals. Investigations into the circuitry underlying rhythmic swimming movements of the gastropod species, and have uncovered intra- and inter-individual variability in synaptic connectivity and serotonergic neuromodulation.

Cnidarian hair cell development illuminates an ancient role for the class IV POU transcription factor in defining mechanoreceptor identity.

Although specialized mechanosensory cells are found across animal phylogeny, early evolutionary histories of mechanoreceptor development remain enigmatic. Cnidaria (e.g.

Evolutionary insights into T-type Ca channel structure, function, and ion selectivity from the homologue.

Four-domain voltage-gated Ca (Ca) channels play fundamental roles in the nervous system, but little is known about when or how their unique properties and cellular roles evolved. Of the three types of metazoan Ca channels, Ca1 (L-type), Ca2 (P/Q-, N- and R-type) and Ca3 (T-type), Ca3 channels are optimized for regulating cellular excitability because of their fast kinetics and low activation voltages. These same properties permit Ca3 channels to drive low-threshold exocytosis in select neurons and neurosecretory cells.

Recruitment of Polysynaptic Connections Underlies Functional Recovery of a Neural Circuit after Lesion.

The recruitment of additional neurons to neural circuits often occurs in accordance with changing functional demands. Here we found that synaptic recruitment plays a key role in functional recovery after neural injury. Disconnection of a brain commissure in the nudibranch mollusc, Tritonia diomedea, impairs swimming behavior by eliminating particular synapses in the central pattern generator (CPG) underlying the rhythmic swim motor pattern.

Identification of genes related to learning and memory in the brain transcriptome of the mollusc, Hermissenda crassicornis.

The sea slug Hermissenda crassicornis (Mollusca, Gastropoda, Nudibranchia) has been studied extensively in associative learning paradigms. However, lack of genetic information previously hindered molecular-level investigations. Here, the Hermissenda brain transcriptome was sequenced and assembled de novo, producing 165,743 total transcripts.

Hidden synaptic differences in a neural circuit underlie differential behavioral susceptibility to a neural injury.

Individuals vary in their responses to stroke and trauma, hampering predictions of outcomes. One reason might be that neural circuits contain hidden variability that becomes relevant only when those individuals are challenged by injury. We found that in the mollusc, Tritonia diomedea, subtle differences between animals within the neural circuit underlying swimming behavior had no behavioral relevance under normal conditions but caused differential vulnerability of the behavior to a particular brain lesion.

Toward locating the source of serotonergic axons in the tail nerve of Aplysia.

Stimulation of the tail nerve (pedal nerve 9, p9) of the mollusk, Aplysia californica, causes release of serotonin (5-HT), which mediates sensitization of withdrawal responses. There are about 35 serotonin-immunoreactive (5-HT-ir) axons in p9, yet the cell bodies of these axons have not been located. Backfills of p9 were combined with 5-HT immunohistochemistry to locate the cell bodies of 5-HT-ir neurons with axons in p9.